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FOR

THE

PROFESSIONAL

SERVICEMAN

to at

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as (t,_z

iru4ustrtj

service b_

FOR

THE

PROFESSIONAL

SERVICEMAN

R/C,: Beckett Corporation

38251 Center Ridge Road

P.O. Box 1289

Elyria, Ohio 44036- !289

1-800_OIL BURN (645-2876)

R.W,BeckettCanada, Ltd.

Unit 3 - 430Laird Road

Guelph, Ontario, Canada NIG 3X7

1-800-665-6972

Acknowledgements

R.W.BeckettCorporation is pleased to present this new,

revised edition of Guide to Oilheatfor the ProfessionalServiceman

(formerly known as The ProfessionalServiceman's Guide to

Oilheat Savings). This new edition has been expanded to include

updated information and several additional topics of importance

to the industry as we approach and enter the 21st Century.

These topics include direct, side-wall venting and outside

combustion air. We hope this new edition will help you achieve

greater success for your business while providing outstanding

service to your customers.

Beckett has distributed many thousands of copies of [his

book, in various editions, since its first printing in 1979.

The original ProfessionalServiceman's Guide to Oilheat Savings

was based primarily on material developed in 1978 by the

Massachusetts Better Home Heat Council and distributed by

them as a manual entitled Oil Heat Energy ConservationManual.

This material is gratefully used with their permission.

The Better Home Heat Council received finandal support for

development of this material through the Massachusetts Energy

Office, as part of the 1978 State Energy Conservation Plan, funded

by the U.S. Department of Energy under PL94-163 and 94-384.

BHHC also received technical assistance from the Walden Division

of Abcor, Inc., and from numerous individual members of

BHHCs Technical Review Committee.

Acknowledgements

VCewishto acknowledgeand thank the followingcompanies

and organizations (listedalphabetically)that suppliedillustrations,

photos, and/or information used in the revisededitionof thisbook:

Bacharach,Inc.

Broo'yahavenNationalLaboratory

DanfossAutomaticControls

DelavanInc.

FieldControls

HagoManufacturing

LynnProductsCo.

PetroleumMarketersAssociationofAmerica

$untecIndustriesIra:.

Testo,Inc.

Thermo-DynamicsBoilerCo.

TjernlundProducts,Inc.

Trianco-Heatmak_r,Inc.

Ifwe haveinadvertentlyleft anyoneoff this list,wesincerely

apologize,and assureyou that your contribution isvery

much appreciated.

TABLE OF CONTENTS

CHAPTER 1 COMBUSTION THEORY ................................................................................................. 1

Fuel Oil ............................................................................................................................. 1

Combustion ....................................................................................................................... 2

Role of Excess Air in Combustion .................................................................................... 4

Excess Air - Smoke Relationship ....................................................................................... 5

Effect of Air Leaks ............................................................................................................ 6

CtD_FrER 2 OILHEAT SYSTEMS ......................................................................................................... 7

Overview of Oilheat Systems ........................................................................................... 7

Basic Oil Burner Design ................................................................................................... 9

Nozzles ........................................................................................................................... 12

Combustion Chambers .................................................................................................... 14

Heat Exchangers ............................................................................................................. 18

Combustion Air Requirements ........................................................................................ 20

Draft ................................................................................................................................ 21

Draft Regulators .............................................................................................................. 22

Flue and Chimney Exhaust ............................................................................................. 24

"ventingMultiple Appliances ........................................................................................... 24

Alternative "ventingSystems ........................................................................................... 25

Power Chimney Venting ................................................................................................. 25

Side-Wall Venting ........................................................................................................... 25

Power Venting ................................................................................................................. 29

Direct Venting ................................................................................................................. 29

Sealed Combustion ......................................................................................................... 29

Outdoor Units ................................................................................................................. 29

CHAPTER 3 EFFICIENCY - DEFINITION OF VARIOUS TYPES OF EFFICIENCY .................. 30

Combustion Efficiency ...................... ............................................................................. 30

Steady_State Efficiency ................................................................................................... 30

AFUE Ratings ................................................................................................................. 30

CHAPTER 4 STEADY-STATE EFFICIENCY MEASUREMENTS ................................................... 32

Stack Loss Theory .......................................................................................................... 32

Measurement of Carbon Dioxide or Oxygen .................................................................. 36

Alternative Measurement Techniques ............................................................................. 38

Other Advanced Multi-Purpose Test Instruments ........................................................... 38

Measurement of Flue Gas %mperature .......................................................................... 39

Smoke Measurement ....................................................................................................... 40

Draft................................................................................................................................ 41

Carbon Monoxide Testing ............................................................................................... 42

CHAPTER 5RESIDENTIAL OIL BURNER ADJUSTMENTS ......................................................... 44

Facts About High CO 2 Levels ........................................................................................ 44

Procedure Preparation Steps ......................................................................................... 45

Combustion Adjustment Steps ........................................................................................ 46

Recording of Readings .................................................................................................... 47

The Annual Clean-Up ..................................................................................................... 47

Test Report Form ............................................................................................................ 49

Basic Troubleshooting .................................................................................................... 50

CHAPTER 6 ENERGY CONSERVATION OPTIONS ........................................................................ 52

Flame Retention Oil Burners .......................................................................................... 52

Criteria for Installing Name Retention Oil Burners ....................................................... 53

Installation of Matched BoileffBurner or Furnace/Burner Systems ................................ 55

LIST OF FIGURES

FIGURE PAGE

1 Viscosity vs. temperature, No. 2 fuel oil .......... 1

2 "viscosityconversion, Centistokes vs. Saybolt

Universal Seconds............................................. 1

3 Combustion products by weight and volume,

1 lb. fuel oil, 0% excess air...............................3

4 Combustion products by weight and volume,

1 lb. fuel oil, 50% excess air ............................. 3

5 Relationship between excess air and CO2 .......4

6 Effect of excess air on CO2 .............................. 5

7 Effect of excess air on combustion gas

temperature ........................................................ 5

8 Smoke & efficiency vs. excess air curve .......... 6

9 Typical oilheat system components .................. 7

10 Underground tank ............................................. 7

11 Above ground tank ............................................7

12 Indoor tank ........................................................ 8

13 Typical oil burner components ....................... 10

14 Burner air patterns ........................................... 10

15 Burner flame configurations ........................... 11

16 Cutaway view of a fuel oil nozzle .................. 12

17 Beckett Multi-Purpose Gauge ......................... 13

18 Nozzle spray patterns ...................................... !3

19 Combustion chamber design .......................... 14

20 Air tube insertion ............................................ 15

21 Soft fiber refractory combustion

chambers ......................................................... 16

22 Combustion chamber sizing data.................... t7

23 Recommended minimum inside dimensions

of refractory-type combustion chambers ........ 17

24 Heat exchanger designs .................................. !8

25 Oil furnace heat exchanger ............................. 19

26 Condensing furnace heat exchanger ............... 19

27 Approximate relationship of % excess air

with flame temperature and volume of

combustion cases ............................................ 19

28 Outside air combustion ...................................20

29 Tjernlund Combustion Air In-ForcerTM .......... 21

30 Draft changes in a chimney ............................ 22

31 Field draft controls .......................................... 23

32 Common chimney sizes vs. Btu input ............ 24

33 Multiple appliances vented separately ............ 24

34 Square inch area of flue collars ...................... 25

35 Tapered manifold vent system ........................ 25

36 Constant sized manifold vent system ............. 25

37 Barometric damper locations when venting

multiple appliances ......................................... 26

FIGURE

PAGE

Power chimney venting system ..................... 26

Efficiency vs. net stack temperature ............... 26

Common chimney troubles and

theircorrections ............................................... 27

41 Power side-wall venting.................................. 28

42 Field power venter .......................................... 28

43 Sealed combustion furnace and boiler ............ 28

44 Outdoor appliance installation ........................ 29

45 Distribution of heat as determined by the

stack loss method ............................................ 32

46 Theoretical combustion relationship between

CO2 and 0 2 for No. 2 heating oil .................. 33

47 CO2 gas analyzer ............................................ 34

48 Graph of heating appliance efficiency ............ 34

49 No. 2 fuel oil efficiency table ......................... 35

50 Construction of CO2 analyzer ........................ 36

51 Lynn Model 6500 Combustion Efficiency

Analyzer .......................................................... 38

52 Testo 342 Combustion Analyzer ..................... 38

53 Bacharach CA 40H Combustion

Analyzer .......................................................... 39

54 Flue gas thermometers .................................... 39

55 Bacharach smoke spot tester ........................... 40

56 Oil burner smoke scale.................................... 41

57 Draft measurement devices ............................. 41

58 Lynn Model 7400 Carbon Monoxide

Analyzer .......................................................... 42

59 CO level standards .......................................... 43

60 Flue pipe sampling hole locations .................. 44

61 Correlation of percent of CO2, 0 2 and

excess air ......................................................... 45

62 Typical smoke vs, CO2 percent ...................... 46

63 Test report form ............................................... 49

64 Name retention combustion heads ................. 52

65 Non-flame retention and flame retention

combustion ...................................................... 53

66 Recommended firing rates for Beckett AF

and AFG burners ............................................. 53

67 Beckett AF II air tube combination and

firing rate chart ................................................ 54

68 Air tube/head combinations for wet base

and wet leg boilers .......................................... 54

69 Name retention heads for furnaces,

dry base boilers, and water heaters ................. 55

70 Outdoor winter design temperatures............... 56

7t Nozzle manufacturers, spray patterns,

and capacities .................................................. 58

PurposeofManual

This manual has been prepared for use by oilheat

service managers and service technicians_

It provides a brief overview of oilheat systems,

as well as a review of basic oil burner combustion

theory. Included are suggested procedures for

adjusting and maintaining oil burners-and other

oilheat system components-to provide your

customers with maximum efficiency,comfort,

and safety.

Modification and installation procedures recom-

mended herein apply to domestic oil burners installed

in houses ranging from single-family dwellings to

multi-family units They apply generally to a capacity

range up to approximately 400,000 Btu/hr. input.

The proceduresin this document should be used

as a supplement to the equipmentmanufacturer's

recommendedinstallationand serviceinstructions

and do not precludeother acceptedguideline

documents on goodindustry practice,

This chapter reviews the basic concepts about the

process of combustion. You should understand

this process before tackling the other chapters in

this manual! It's likely that a good deal of

material presented is familiar to you, but there's

an even better chance that you might learn

something new. It's worth reading, since this

information develops the foundation from which

every dependable oilheat service technician

should work.

FUEL OIL

No. 2 distillate fuel oil (domestic heating oil) is a

product of the refining of crude oil, which was

formed underground through decomposition of

marine organisms, fish, and vegetation. This

organic matter eventually became liquid or gas

concentrated underground in pockets or pools.

All petroleum products, including natural gas,

gasoline, kerosine, No, 2 fuel oil, etc., axe

chemical compounds that make up crude oil, and

they all contain carbon and hydrogen.

The process of separating these various compo-

nents can be quite complex, but is commonly

referred to as "refining". Eventually, one of the

products of the refining process is No. 2 fuel oil,

which is suitable for use as a fuel in residential

oil burners. The designation "No. 2" is used as

a specification guide that defines some physical

characteristics such as flash point, ash,

viscosity, etc.

All fuel oil is not alike, and variations can have

an impact on burner operation. Here are a few of

the variations within each grade of fuel oil which

are measured by ASTM (American Society for

Testing and Materials standards):

VISCOSITY vs. TEMPERATURE No, 2 Fuel Oil -TYPICAL

30 -- _'%._%.

20 40 60 80 100

TEMPERATURE _F

FIGURE 1 Viscosity vs. temperature, No. 2 fuel oil

CENT1STOKESvs.SAYSOLTUNWERSAL SECONDS VISCOSITy"CONVERSION ATi 00' F

iUJ _

02 _,. ............ ,

3o 3"I _2 3'334 3s 36 37 _ 39 40

SAYBOLT UNIVERSAL SECONDS

FIGURE 2 \_scosity conversion,Centistokesvs.Saybolt

UniversalSeconds

This is the oil's resistance to flow. The viscosity

rating is a measure of how much oil flows

through a standard orifice within a certain amount

of time. Oil with high viscosity can contribute to

poor atomization, delayed ignition, noisy flame or

pulsation, increased input and possible sooting.

This is particularly true in temperatures below

50°E (See Fig, 1,) Viscosity measured by the

Kinematic viscometer is reported in centistokes.

(See Fig. 2 for cross reference.)

Pour Point

Pourpoint is the temperature at which oil will

barely flow. This is usually 5°F above the point

where oil forms a solid mass. The ASTM D396

Standard for fuel oils lists 20°F as the maximum

pour point for No. 2 fuel oils. However, random

analyses show that the typical pour point is

approximately -20°E To avoid problems in

certain cold ambient applications, No. 2 fuel oil is

sometimes blended with approximately 25% or

more of No. 1 distillate fuel (kerosine) to lower

the pour and cloud points.

Cloud Point

This is the temperature at which wax crystals

begin to form, typically 10°to 20°F above the

pour point. These crystals can clog filters and

strainers, restricting oil flow. Raising the oil

temperature causes the wax to go back into

solution. ASTM D396 does not list a specification

on cloud point.

Distillation Temperature

No. 2 fuel oil can be vaporized and distilled

(condensed) to determine the volatile compo-

nents. Modern refinery methods use straight-run

distillation and catalytic cracking processes,

resulting in slightly different chemical hydrocar-

bon composition which can affect combustion

performance. Therefore, the distillation tempera-

turetestisvaluable.It consistsoffueloilbeing

heatedgraduallyinaflaskuntilitvaporizes,then

iscondensedintoagraduatedcylinder.The

temperatureatwhichcondensationbeginsis

calledtheinitialboilingpoint(IBP).Therising

temperatureisrecordedforeachfractiondistilled.

Itisusuallyreportedin10%incrementsuntilthe

finaldropisrecoveredorendpointisreached.

Theinitialboilingpointcouldcauseignition

problemsif it istoohigh(over400°F).The

ignitionarcmustprovideenoughheatenergyto

elevatethetemperatureoftheatomizedoil

dropletstotheinitialboilingpoint.If theIBPis

low,theignitionshouldbeimmediate.Forthe

flametobesustained,the10%pointortempera-

tureatwhich10%ofthetotalvolumeisdistilled

mustberelativelyclose.If thespreadistoolarge,

thentheflamecouldpulsateorevenbeextin-

guished.

Foranestablishedflame,theremainingfractions

of20-80%shouldnotpresentanycombustion

problems,butthe90%andtheendpointcould.

The90%pointisthetemperaturewhere90%of

theoilisdistilled.ASTMD396requiresthistobe

between540°Fminimumand640°E

Awidespreadbetweenthe90%andendpoint

cancausepoorcombustion,sootaridcarbon

depositsontheheatexchangerbecausethe

remainingheavyendsmaynotburncompletely.

Detecting "Out of Spec" Oil

Your first clue that oil is not within ASTM specs

might be a sudden rash of problems: delayed

ignition, smoky fires, appliance sooting and

noisy, dirty flames. If an analysis by a competent

laboratory shows the oil is out of spec, the

supplier should be advised. However, if it is

within spec, but is near the maximum level for

viscosity, pour point or has an IBP above 400°E

chemical additives or blending with about 25%

kerosine might be considered to make the oil

more compatible with cold temperatures, and to

improve its ignition and combustion qualities.

COMBUSTION

When fuel oil is burned, the chemical energy that

is stored in the oil is released in another form of

energy: heat. But to create this conversion of

energy, an external source of heat must be applied

to the oil droplets to start the reaction. The

electric spark delivered by the electrodes of an oil

burner provides the initial heat. The heat from the

electrodes causes oil droplets to become oil vapor

and eventually burn continuously. This burning

then heats the surrounding oil droplets causing

them to bum. This process continues until all or

most of the droplets are vaporizing and burning.

If the conditions for combustion are ideal, all oil

droplets will burn completely and cleanly within

the combustion zone.

Combustion is the process of burning, p

Combustion, as we normally think of it, is

generally described as "rapid oxidation" of any

material which is classified as combustible

matter. The term "oxidation" simply means the

adding of oxygen in a chemical reaction, and

"combustible matter" means any substance which

combines readily and rapidly with oxygen under

certain favorable conditions. Since fuel oil

primarily consists of carbon (85%) and hydrogen

(15%), combustion of fuel oil, according to our

previous definition, is the rapid combining of

carbon and hydrogen with oxygen.

As you know, the oxygen needed for combustion

comes from the air provided by the burner

blower. Approximately 21% of the air is oxygen.

The other 79% is nitrogen. Therefore, to supply

the oxygen needed for combustion, a great deal of

nitrogen goes along for a free fide. This will

become an important factor in later discussions of

proper oil burner adjustment!

What we see and feel from combustion--flames,

smoke, heat--is a result of chemical reactions.

Since we can't see carbon, hydrogen or oxygen

atoms (smallest units to combine), we symbolize

the reactions with formulas that describe the

process. For example:

Carbon +Air oxygen + ] f_

nitrogen J

carbon dioxide + nitrogen + heat (1)

Hydrogen +Air [ oxygen +

nitrogen ]

water vapor + nitrogen + heat (2)

These reactions can be rewritten using symbols in

the following manner:

C+O2+N 2 -_ CO2+N2+heat (1)

2H2+O2+N 2 -_ 2H20+N2+heat (2)

Both chemical reactions produce entirely new

products, and each reaction gives off heat.

However, you may have noticed that in

each reaction nitrogen (N2) has not changed,

OIL

(t pound)

-t-

AIR

(14_36 pounds

or 188 cubic feet)

[Air is 20.9% oxygen

and 79.1% nitrogen]

1.00 lb. oil

14.36 lb. air

15.36 ib. total

[

I WATER

(1.18 pounds)

(amount of water vapor is

not considered in % of

CO2 determination

FORMS > I

84.7% by volume

NITROGEN

(11.02 pounds or

150 cubic feet)

15.3% by volume

CARBON DIOXIDE

(3.16 pounds or

27.2 cubic feet)

1.18 lb. water

11.02 lb. nitrogen

3,16 lb. carbon dioxide

15.36 lb. total

FIGURE 3Amount by weightand volumeof

combustion products when 1 lb. of fuel oil is burned

(0% excess air)

OIL

(1 pound)

-I-

50 pementexcess

AIR

(21.54 pounds

or281 cubicfeet)

[Airis 20,9%oxygen

and 79.1%nitrogen]

1,00 lb. oil

21.54 lb. air

22.54 lb. total

FORMS _)

WATER ](1.18 pounds)

56.1% by volume

NITROGEN

(11.02 pounds or

150 cubic feet)

10.2% byvolume ]

CARBON DIOXIDE l

(3.16 pounds or

27.2 cubic feet)

33.8% by volume i

EXCESS AIR !

(7.18 pounds or

90.4 cubic feet)

1.18 lb. water

11.02 lb. nitrogen

3.16 lb. carbon dioxide

7.18 lb. excess air

22.54 lb. total

FIGURE 4 Amount by weight and volume ofcombus-

tion products when 1 lb. of fuel oil is burned (50%

excess air)

indicating that nitrogen does not participate in

the reaction. Consequently, because of the

large amounts of nitrogen in the air, the bulk of

the flue gas is made up of unreacted nitrogen.

Note: Some nitrogen does react with oxygen

to create a small amount of nitrogen oxides or

NOx.

If exactly the right amount of air (no excess

air) were supplied for complete combustion of

the carbon and hydrogen in the fuel oil, the

products of combustion would be as indicated

in Figure 3. However, with typical oilheat

equipment, it is usually not possible to get a

perfect mixture in which all the carbon and

hydrogen are supplied with the exactly correct

quantity of oxygen. To insure that all the

carbon and hydrogen come into contact with

enough oxygen to burn completely, excess air

must be supplied, The excess air is simply air

over and above the theoretical requirement for

the combustion of fuel oil. With excess air

needed for combustion, reaction (1) becomes:

C+02+N 2 -* C02+N2+O2+heat (3)

Note that the only difference between reaction

(3) and reaction (1) is that 0 2 (oxygen) is a

product of the reaction. This 0 2 is the oxygen

in the excess air that does not combine with

carbon to make carbon dioxide. In essence,

extra 0 2 is provided, as a component of the

excess air, to ensure that all the carbon and

hydrogen comes in contact with the oxygen

and bums.

This excess air does not react during the

combustion process, but enters the heating unit

at room temperature and reduces the tempera-

ture of the combustion gases so less heat is

available to be transferred to the distribution

medium. As a result, excess air is a source of

heat loss. By introducing 50% excess air, the

situation shown in Figure 4 is created.

Compare this with Figure 3. Note that:

Y The amount (weight) of H20, CO2,

and N2 formed in Figure 4 is the

same as that in Figure 3.

•'Percent by volume of CO2 and N2 in

Figure 4 is less than is formed in

Figure 3.

_' Oxygen (_ partof excess air) is a

pr_._ductin Figure4 but not in Egtue 3.

ILl

-J

It.

LI.I

I3u

!!II!!

MEASURE PERCENT CO 2TO D_ERMINE _

PERCENT EXCESS AIR

_" _IIii _._,m_mi " .iii--

0 i0 20 3o 4o so eo 7o 8o 90 i30 i40 1;50

PERCENT EXCESS AIR

FIGURE 5 Relationship between excess air and CO2

In Figure 4, since 20.9 percent of the excess air is

oxygen, 7.1 percent of all the combustion gases is

oxygen. You determine this by multiplying the

percent excess air (33.8%) times that portion of

excess air which is oxygen (.209). This gives

approximately 7.1 percent oxygen.

Note that in Figure 4 the percentage of CO 2 or

0 2 changed from Figure 3 as a result of excess

air, therefore, we can use the percent CO 2 or 0 2

in the flue as a measure of excess air or vice versa

las a general rule.

'_' The more CO 2, the less excess air

•'The more 0 2, the more excess air

Figure 5 displays the relationship between CO 2

and excess air.

The above discussion is a simplification of the

actual combustion process. The chemical

reactions provided are only those that are

important to the overall combustion process.

Nevertheless, the information in this section is

sufficient to support you in your oil burner

service work. Make sure you understand the

concepts and, if necessary, reread this section or

ask a knowledgeable person to assist you. Don't

go on without understanding the basic concepts!

ROLE OF EXCESS AIR

IN COMBUSTION

You have seen that excess air must be supplied to

insure adequate mixing of fuel and oxygen.

However, excess air is one of the major causes of

low efficiencies. To see how this occurs consider

that excess air:

Ydilutes combustion gases

Yabsorbs heat

•'drops overall temperature of combustion gases

The dilution of combustion gases occurs simply

because of the presence of additional gas in the

form of excess air. The excess air absorbs heat in

the combustion zone and reduces the flame

temperature. This in turn reduces the transfer of

heat to the heat exchanger since a significant

amount of heat is transferred by radiation.

Moreover, as excess air is introduced, the overall

temperature of the combustion gases drops

because the heat from these combustion gases is

used to raise the temperature of the excess air.

Think of this process as being similar to adding

refrigerated cream to a cup of coffee as shown in

Figure 7. The cup of coffee is originally 160°F

(high temperature) and occupies a small volume

(half a cup). Adding cream at 40°F increases the

volume (almost a full cup) and lowers the overall

temperature to 120°F (mild temperature). Note

that the temperature of the mixed coffee and

cream is higher than the temperature of the cream

alone and lower than the temperature of the

coffee alone. Heat from the coffee went into

heating the cream and the overall temperature

dropped. In other words, the cream absorbed

some heat from the coffee.

Also,bylookingatFigure6youcanseethatthe

coffeeexampleillustratestheeffectofexcessair

(shownaswater)indilutingthegas(coffee)and

theresultingreductionintheCO2percent.

Bearinmindthatthistemperaturereductionand

dilutiontakesplaceinthecombustionzone,not

intheflueorstack.Itisimportanttonotethatthe

effectofexcessaironthetemperatureoftheflue

gasisdifferent.Withmoreexcessair,thefluegas

Water (Excess Air)

Cream 1CO21

_._ coffee

(C02)

% Cream =13.6%

85+15+10

Amount of

CO2 remains

the same,

the percent

of CO2is

less

Cream (CO 2)

.,,...,_ ( N t oge | _,,_,,...,,._

(C02)

% Cream 15%

85+15

FIGURE 6 The effectof excess air on CO2

Addingexcessairtoflameislikeaddingcreamtoacup ofcoffee.

temperature tends to rise. This happens because

the volume of combustion gas per unit of fuel

burned is now greater than before, so the gases

pass over the heat exchanger surfaces more

rapidly, reducing the contact time. This reduces

the heat transfer rate to the heat exchanger.

To review, remember that excess air causes the

following:

•'lower flame temperature

Y lower combustion gas temperature

T higher flue stack gas temperature

T poorer heat exchange to the distribution

medium

.SmallVolume

•HighTemperature

All of these changes reduce the efficiency of the

heating system• So minimizing excess air is

essential in the proper adjustment of oil burners.

However, you will find out in the next section

that simply reducing excess air without concern

for other factors could lead to a great deal of

trouble! Keep reading, you'll see what we mean.

. LargerVolume

•LowerTemperature

Excess Air. Smoke Relationship

During the combustion of oil, some smoke is

usually generated, since some of the oil droplets

do not contact enough oxygen to complete the

reaction which forms carbon dioxide. This smoke

consists of small particles of mainly unburned

carbon. Some of these particles stick to the heat

exchanger surfaces acting as insulation and can

eventually clog up the flue passages, while others

are emitted through the stack.

Now you are ready for discussion of the issue that

is all important to the proper adjustment of oil

burners: excess air-smoke

relationship.

You have learned that

there must be sufficient

excess air to provide good

mixing of combustion air

and fuel oil. Wqthout this

excess air, incomplete

combustion occurs and

smoke is formed. Thus, to

minimize smoke, you

generally add excess air.

FIGURE 7 Representation of theeffect of excess air on

combustion gas temperature

Unfortunately, as you have learned, as the amount

of excess air is increased, the transfer of heat to

the heat exchange medium (hot water, warm air,

or steam) is reduced. A delicate balance must be

achieved between smoke generation (caused by

insufficient excess air), reduced heat transfer (due

to reduced combustion gas temperature), and an

increased volume of combustion products (caused

by unnecessary excess air). Figure 8 illustrates

the typical relationship between smoke, effi-

ciency, and excess air. Notice that smoke and

efficiency increase as the excess air is decreased.

The exact shape of this curve varies from unit to

unit. Knowing this, the curve can give you a

general idea of where the burner air should be

adjusted. The highest efficiency occurs when you

properly balance the trade-off between smoke

and excess air.

Effect of Air Leaks

Now that you understand what goes on inside the

heating unit, it will be easier to follow why air

leakage into the appliance causes lost efficiency.

This air leaks into the combustion gases before

they pass through the heat exchanger and acts

like excess air. The air leaks dilute the combus-

tion gases, cooling them and increasing their

volume so that they pass through the heat

exchanger more quickly, However, an air leak is

even worse than excess air in the combustion

chamber because an air leak can not reduce the

smoke formed in the combustion zone.

Excess combustion air reduces heating plant efficiency.

Too much smoke will eventually reduce efficiency also.

Recommended

LLI

<1 Operating Level

o')

k'_L SMOKE

i i

o% % Excess Combustion Air

FIGURE 8 Smoke & efficiency vs. excess air curve

OILHEAT SYSTEMS

OVERVIEW OF OILHEAT SYSTEMS

The primapy emphasis of this manual is on oil

burners. However, a brief look at total oilheat

systems would be appropriate. Maximum heating

efficiency, reliability, and safety cannot be

achieved unless all components of the system are

compatible and in top working condition. It is

vital, therefore, that the technician consider the

entire system when installing new equipment or

servicing existing equipment.

The purpose of any oilheat system is to convert

fuel oil into heat, and distribute as much of that

heat as possible to the home.

Typical Oilheat System Components

HOU_

Barometric _Chimney

Draft Control

_, Tile Liner

_Heat __;>

Cooled Exchan_ Heated

Water or Air Water or Air

(from house (to heat

house)

RGURE 9 _pi_l oilheatsystem components

Storage Tanks

Residential fuel oil storage tan_ksfall into three

categories: underground, above ground, and indoor.

Each has i_ advantages and disadvantages.

Underground Tanks

Courtesy of Suntec tr_ustdes, In_

FIGURE10Undergroundtank

Advantages:

(1) Take up no space inside or outside the home.

(2) Tanks are out of sight,

(3) A large quantity of oil can be conveniently

stored.

(4) Better insulation from cold, compared to

above ground tanks.

Disadvantages:

(1) ExNnsive to install, inspect, and service.

(2) Subject to effects of cold and underground

moisture.

(3) Well-made, properly installed tanks seldom

leak_ven after decades of service. How-

ever, leak detection and clean up are still

important environmental concerns.

Above Ground Tanks

Courtesy of Suntec Industries, Inc.

UNIT

FIGURE 11 Above ground tank

Advantages

(I) less expensive than underground tanks to

install and service.

(2) If leaks occur, they can be easily detected in

time to avoid environmental problems.

Disadvantages:

(1) Exposed to cold and moisture. (These

problems can be reduced by providing a

shelter for the _k.)

(2) Take up outdoor space.

(3) May detract from appearance of home.

Indoor Tanks

VENTll_

Courtesy of Suntec Industries, Inc.

• 1%" MIN.

_LK_ SHUT-OFFVALVE

LINE

FIGURE 12 Indoor tank

Advantages:

(1) Not affected by outside cold and moisture.

(2) Less expensive to install and service than

underground tanks.

(3) Leaks are unlikely to occur. If they do, they

are easily spotted and repaired.

Disadvantages:

(1) Take up space inside home.

(2) Some oil smell may be present.

Oil Delivery Systems

The oil delivery system includes all components

required to transport oil from the storage tank

to the burner. These include pumps, pipes,

valves, filters, and controls. Inspecting these

components should be a part of scheduled

maintenance service.

When diagnosing combustion problems, the oil

delivery system should always be considered as

a possible contributing factor. Check for proper

oil pressure, viscosity, and cleanliness. Filters

should be changed at regular intervals. Compres-

sion fittings can cause air leaks and should not

be used.

In some cases combustion problems can be

alleviated by increasing oil pressure to the

nozzle. If cold oil is a problem, oil line heaters

can be installed. Always follow burner

manufacturer's instvactions when adjusting oil

pressure or installing heaters.

Oil Burners

The functions of an oil burner are to break fuel oil

into small droplets, mix the droplets with air, and

ignite the resulting spray to form a flame.

Combustion Chambers

The purpose of the combustion chamber is to

reflect heat back into the flame to aid the combus-

tion process and achieve more complete burning

of oil. See page 14 for more details.

Heat Exchangers

The purpose of the heat exchanger is to transfer

heat from the burner flame to the water or air used

to heat the home. The heat exchanger is an

integral part of the boiler or furnace. The role of

the serviceman is usually limited to inspection

and cleaning. However, this is an extremely

important role. If soot is allowed to accumulate on

the heat exchanger, the efficiency of the heating

appliance can be seriously impaired. Proper

adjustment of the burner to avoid smoke (the

cause of soot) is essential to keeping the heat

exchanger clean. See page 18 for more details.

Flue Pipes

Flue pipes serve two vital functions:

(1) They convey combustion gases from the

heating appliance to the chimney or vent.

Since these gases are potentially harmful to the

home and its residents, these pipes must be

sealed tightly to prevent leakage. In most

chimney systems, flue pipes are under a

negative pressure created by draft, which aids

in preventing leaks.

(2) Flue pipes convey combustion gases that

create the draft to assist in drawing com-

bustion air into and through the burner in

chimney systems.

Draft Regulators

Many flue pipes include a barometric draft

regulator. This consists of a counterweighted

swinging door which opens and closes to help

maintain a constant level of draft over the fire.

Modern high-speed, flame retention burners are

much less sensitive to changes in natural draft

allowing draft regulators to be eliminated in some

cases. However, check the burner manufacturer's

instructions, and local codes, before eliminating

draft regulators. See page 22 for more details.

Chimneys

Chimneys have been used since the earliest days

of indoor heating to draw combustion gases out of

the home and provide draft to help draw in

combustion air. Correct chimney design and

careful maintenance are essential to the operation

of any oilheat system.

When chimneys are inadequate or absent entirely

(such as in electric-to-oil conversions), alternative

venting systems are available. See page 25 for

more details.

Heat Distribution Systems

With furnaces, warm air, propelled by fans, is

distributed throughout the house through metal

ducts. With boilers, hot water or steam is distrib-

uted through pipes. These heat distribution

systems can be important sources of heat loss.

Check air ducts for leaks, and consider insulation

for water and steam pipes.

Controls

The controls used to regulate typical oilheat

systems include the following:

(1) The Thermostat "tells" the burner when to

turn on and off to maintain the desired

temperature in the house. Programmable

thermostats automatically lower and raise

temperature settings at timed intervals

throughout the day and night, to conform to

the changing ne_edsof the home occupants.

This can produce significant fuel savings.

(2) TheAquastat regulates the temperature of

boiler water.

(3) The Fan Control turns the fan on and off in

warm air furnace systems.

(4) Pump and Zone "/hive Controls regulate the

flow of water or steam in boiler systems.

(5) Safety Controls such as pressure relief

valves, high temperature limits, low water cut

offs, and burner primary controls protect

against appliance malfunctions.

When adjusting controls, follow manufacturer's

instructions.

The House

The house itself has a major effect on the

performance of the heating system, especially on

the combustion air supply. Newer, tightly sealed

houses have different requirements than older

houses with greater air infiltration. Exhaust fans,

vented clothes dryers, and ventilating systems

also have an effect on available air for combus-

tion. It is essential that the technician consider

these factors when recommending a heating

system, or diagnosing system problems.

BASIC OIL BURNER DESIGN

Most oil burners in use today operate as follows:

(See Figure 13.)

(1) Oil is delivered under pressure (usually about

100 psig--although some models require

pressures in the 140-200 psig range) by the oil

pump (A) to the nozzle (B). Check

manufacturer's specifications for proper pump

pressure settings.

(2) The nozzle breaks up the oil into a spray of

tiny droplets from .0002 to .0100 inches in

diameter which evaporate rapidly into a

vapor.

(3) The vapor is mixed at the burner head with a

stream of air from the blower wheel (C).

(4) The oil vapor combines with oxygen from the

air stream and is ignited (initially) by an

electric arc from the electrodes (D), powered

by a high voltage transformer (E), to produce

a flame.

(5) Heat is reflected back into the flame by the

combustion chamber, to help evaporate the oil

droplets. This helps achieve more complete

burning of the oil.

(6) This combustion process continues until the

burner is shut down for the off cycle.

(7) The entire process begins again with the next

on cycle. 9

NOZZLE

ELE

CLAMP SCREW _ STA_dC PLATE _\

SPtDER SPACER ASS'Y J _- KNURLED NUT

FIGURE 13 Typicaloilburner components

Flame Retention Burners

Most oil burners currently being manufactured

and installed are flame retention burners. The

name comes from the combustion heads which

are designed to hold-in or "retain" the flame.

High-speed motors are used to produce high air

pressures. This allows the burner to do a superior

job of mixing air and oil. An intense swirling

motion produces a compact, highly stable flame

which is held (retained) close to the burner head.

Flame gases are recirculated, to aid evaporation

of oil droplets and achieve cleaner, more

efficient combustion compared to non-flame

retention burners.

In most cases, your customers can obtain

substantially improved heating system efficiency

by replacing old non-flame retention burners with

new high-speed flame retention burners. Beckett

supplies a full line of these burners to accommo-

date a wide range of residential and conur_ercial

boilers and furnaces. See Chapter 6 for specific

burner recommendations.

Combustion Heads

The combustion head (also referred to as the

turbulator, fire ring, retention ring, or end cone)

creates a specific pattern of air at the end of

the air tube. The air is directed in such a way

as to force oxygen into the oil spray so the oil

can burn.

Flame Retention Heads vs.

Non-Flame Retention Heads

The majority of combustion heads in the field

today are flame retention heads. These heads

differ from the non-flame retention heads in that

the flame is held very close to the face of the

head. The flame is smaller and more compact,

and usually is 300°F to 500°F hotter than with

non-flame retention heads. (See Figure 15.)

The flame retention head incorporates three basic

elements: (1) center opening, (2) primary slots,

and (3) secondary opening. The center opening

is an orifice in the center of the head which

allows the oil spray and the electrode spark to

pass through the head. The primary slots are the

slots that radiate out from the center opening

toward the outside of the head. The secondary

opening is a slot which is concentric to the

center opening and follows the circumference of

the combustion head. All three openings affect the

way air is delivered to the oil spray.

Air Pattern- Non-Flame Retention Burner

Air Pattern-FlameRetentionBurner

10 FIGURE14Burnerair patterns

Generally speaking, it is advisable to choose a

flame retention head over a non-flame retention

head in the majority of applications. There are a

few existing heating units in the field which have

used a non-flame retention head in a steel

chamber. These units can be retrofitted with a

new burner and non-flame retention head, or

could use a flame retention head with the

addition of a chamber liner for protection against

the hotter flame temperatures produced by the

flame retention head.

Non-Flame Retention Burner

Combustion Head 0

Cast Iron

FlameRetentionBurner

FIGURE 15 Burner flame configurations

Fixed Heads vs. Variable Heads

Most flame retention heads found today can be

classified as either fixed head or variable head.

The only major difference is the method of

controlling the secondary opening. The fixed head

group has the secondary opening preset to a

specific size for a specific firing rate range. The

variable head group allows the head to move

forward and backward according to the firing rate

requirements.

The fixed head is an excellent performer in most

warm air applications. Since the chamber in

these units becomes approximately 2000°E any

oil which is not burned in the flame is usually

ignited by the heat of the chamber. As with warm

air units, a fixed head will also work very well in

the majority of boiler applications.

The variable head is an excellent performer in

most wet base or wet leg boiler applications that

have minimal or no combustion refractory. The

variable head gives the user two advantages over

the fixed head. The first advantage is the ability

to fine tune the position of the head so as to

supply the flame with the precise amount of air

through the secondary slot that it needs in order

to achieve the highest performance levels. The

second advantage is that most variable heads are

actually recessed into the air tube, which protects

the flame base from being affected by recirculat-

ing combustion gases within the chamber.

Firing Range

It is always necessary to choose a head ',,chose

firing rate range is closely matched to the firing

'rate requirements of the heating unit. As an

example, if the firing rate of the heating unit is

1.50 gph, head #1 has a range of .85-1.65 gph,

and head #2 has a range of 1.10-2.00 gph, the

head to choose for the highest performance

would be head #1 (the .85-1.65 gph head),

The reason is that the higher rated head #2 has a

larger secondary slot than the lower rated head to

enable it to reach the top end of its range. Either

head will work, but the higher rated head #2

will probably not reach the same high CO2

performance levels as the lower rated head

because of the extra air it will allow through

the secondary slot.

The Effects of Pre-Purge and

Post-Purge on Oilheat Burners

Without purge capabilities, burner blowers are

turned on at the time the flame is ignited, and

turned off when the flame is extinguished. This

works well in most cases, but some applications

present problems. When a heating system

thermostat signals the need for heat, it is desir-

able to supply it promptly. Any delay in

providing heat can cause discomfort for home or

building occupants, precipitate nuisance service

calls, and have a negative effect on fuel effi-

ciency. To supply heat quickly, the burner flame

must ignite instantly and smoothly. It requires

adequate airflow (draft) to accomplish this.

Typically, when an oil burner has been off for a

while, natural draft in the chimney can become

neutral. Cold chimneys contain heavy air that

must become heated and start to flow upward

before draft can occur. There could even be a

down draft due to wind gusts. In chimneyless,

direct vented systems there may be no draft at

all at start up. With power vented systems, draft

levels may fluctuate widely. That's where pre-purge

comes in.

The pre-purge controls currently offered by

Beckett as a factory-installed option on its models

AF II and AFG burners turn the blower on several

seconds before the flame is ignited. This estab-

lishes the level of airflow required for fast,

smooth ignition. This airflow is already fully

established when ignition occurs. The burner

doesn't have to "struggle" to achieve ignition

under inadequate draft conditions. Another

significant factor is the stability and capacity of

the ignition arc. The arc should be at full strength

and well established when the oil is delivered

from the nozzle--otherwise, delayed ignition,

noisy pulsation, and smoking can occur under

certain adverse conditions. With pre-purge, the

arc is allowed to reach its maximum potential,

contributing to easier ignition of the oil droplets,

and producing a cleaner burning flame from the

moment of ignition. In addition, the oil pressure

level in the pump is stabilized well before the oil

solenoid valve opens. Oil is delivered to the

nozzle at a steady pressure, for optimum atomiza-

tion of the fuel.

Post-purge is involved with the other end of the

burner cycle. When the desired heat level in the

home or building has been achieved, the thermo-

stat calls for burner shut-off, which occurs

immediately without post-purge. As a result,

combustion gases may still be present in the flue

without sufficient airflow to evacuate them. Draft

reversals may also occur, forcing flue gases back

into the flue pipe and the combustion chamber.

This can cause odor problems and/or the leaking

of combustion gases into the home. The heat

from the gases can also affect nozzles and other

system components. Post-purge keeps the blower

operating for a selected period after burner shut-

off. Flue gases are evacuated, draft-reversal is

eliminated, and nozzles are protected from

overheating. Most controls used by Beckett are

adjustable to the specific requirements of the

heating system. Direct vent systems have created

a special application for post-purge capability.

With direct venting, the positive air pressure

created by the burner blower is relied on to move

combustion gases through the flue and evacuate

them from the system. It is vital, therefore, that

the blower continue to operate for a period of

time at the end of each burner cycle. In the past,

pre-purge and post-purge capability was obtained

for the most part through retrofit installation of

optional kits. Now, factory-installed controls, like

those offered on the Beckett AF II and AFG

burners, provide greater convenience for oilheat

service technicians, and reduced costs for

homeowners.

Oil burner nozzles come in a wide range of

designs and sizes. It is essential that the correct

nozzle be used in each installation to assure

compatibility with the burner and produce the

desired spray pattern for the appliance in which

the burner is used.

Cutaway View of A Fuel Oil Nozzle

FIGURE16Cutawayviewofa fueloilnozzle

When replacing nozzles, it is usually best to use a

nozzle identical to the one supplied as original

equipment by the burner manufacturer. Consult

burner manufacturer specifications whenever

possible. If these are unavailable, a call to the

manufacturer might be advisable. Do not assume

that the nozzle currently in use is the correct one.

It may have been installed in error during a prior

burner servicing.

In some cases, improved combustion can be

achieved by changing to a nozzle of a size or

design different from that of the original equip-

ment nozzle. However, such changes should be

attempted only after careful consideration of all

relevant factors and checking with the appliance

SERVICEHOTLINE1-800-OIL,BURN

FIGURE 17 Beckett Multi-Purpose Gauge

manufacturer--and post-installation testing

should be done, to make sure the new nozzle is

performing properly.

When installing a nozzle, a gauge should be used

to insure correct depth and concentricity. The

gauge shown in Figure 17 is available from

Beckett, free of charge, on request.

Proper Nozzle Installation

1. Make sure the fuel supply is clean and free of

air or bubbles.

2. Make sure the pump pressure is set properly.

For domestic applications it may be 100 psig

to 200 psig. (Check manufacturer's specifica-

tions.)

3. Inspect the nozzle adapter before installing the

nozzle. If there are deep grooves cut into it from

over-tightening, replace it. Those grooves, or a

scratched surface, can cause leaks.

4. When installing the nozzle, use extreme care

to protect the nozzle orifice and strainer. If the

orifice gets dirt in it, or becomes scratched, it

will not function properly.

5. Do not over tighten the nozzle when tighten-

ing. Excessive tightening can cut grooves into

the adapter and cause leaks when the next

nozzle is installed.

Nozzle Spray Patterns and Angles

The size and shape of an oil burner flame are

determined by the pattern and angle of the oil

spray, which, in turn, are determined by the

design of the nozzle and the pressure of the oil

and air supplied to it.

The three principal types of spray patterns are

solid, hollow, and semi-solid. (See Figure 18.)

Spray angle categories vary from 30° to 90 °.

It is essential that the combustion air pattern

conform to the oil spray pattern. If the air pattern

is too wide, the droplets at the center of the oil

spray will not be exposed to a sufficient quantity

of air for efficient combustion. If the air flow is

too narrow, the droplets on the outside of the oil

spray will not receive sufficient air.

Finally, the shape and size of the flame (deter-

mined by the nozzle design, oil pressure, and air

pressure) must conform to the dimensions of the

combustion chamber. The flame should be large

enough, and shaped in such a way, to almost fill

Solid

Semi-solid

FIGURE 18 Nozzle spray patterns 13

the combustion chamber without actually

touching any part of the chamber surface.

Be sure to follow specifications provided by

manufacturers.

COMBUSTION CHAMBERS

The function of the combustion chamber is to

surround the flame and radiate heat back into the

flame to aid in combustion. The combustion

chamber design and construction helps deter-

mine whether the fuel will be burned efficiently.

The chamber must be made of the correct

material, properly sized for the nozzle firing

rate, shaped correctly, and of the proper height.

The chamber should be designed and built to

provide the maximum space required to burn the

oil needed to fire the heating plant and meet its

load. Unburned droplets of oil should not touch

the chamber surface, especially a cold surface. A

cold surface will reduce combustion tempera-

tures and cause soot and carbon formation. The

hotter the area around the burning zone, the

easier the oil droplets will vaporize and ignite,

and the hotter the flame will be. If the chamber

is too small, the oil will not have enough time

to complete combustion before it strikes the

colder walls.

When the chamber is too large, there will be

areas in the chamber which the flame will not

fill. This causes cooler chamber surfaces and

reduces the reflected heat from the chamber

walls. As a result, the fuel droplets will not

evaporate as rapidly in the cooler chamber and

•,viii be more difficult to burn completely. More

air will be required to burn smoke-free and

the result will be low CO 2 (high 0 2) and

lowered efficiency.

Floor Size. The size of the combustion chamber

is measured in square inches of floor space. The

ideal size for a residential heating system is

about 80 to 90 square inches per gallon of oil. If

the burner is functioning well, and the chamber

has quick heating refractory material and is

properly designed, it is possible in most cases to

use this formula up to 1.50 gph. For residential

use, the chamber should not exceed 95 square

inches per gallon for a high pressure burner.

When the combustion chamber is accurately

sized to the heating plant capacity, using 80 or

Good Combiner;on

Eddy

Curten_

Pockets

Eddy

u_ent

Pockels

FIGURE 19Combustion chamber design

90 square inches per gallon, it is extremely

important that the nozzle pattern and spray angle

conform to the characteristics of the burner air

pattern and that the oil pressure at the nozzle

should be set to the burner manufacturer's

recommendations.

Shape. The majority of combustion chambers are

square, rectangular, cylindrical or round. Curved

surfaces generally produce more complete

mixing of oil and air. They also eliminate the

pockets of air, often present in the corners of

square or rectangular chambers, which reduce the

reflected heat from the chamber walls to the

flame. The air in these corners also does not

usually become a part of the combustion process

with non-flame retention burners and therefore

dilutes the combustion products as they flow

through the heating plant. This is particularly true

of the corners at the front of the chamber where

the oil is sprayed in, because the flame is narrow

and the oil has not been heated up to maximum

temperatureat this point. (SeeFigure 19.)

Modern flame retention burners are not as

dependent on chamber shape.

A well designed chamberwill confine the flame,

and more reflected heat will enter the combustion

process in its early stages. Thiswillaidcombus-

tion and provide much smootherignition.In

makingalterationsinthe chamber,you must keep

in mind thatyou must use the nozzlespray pattern

and angle to fit the chamberas recommendedby

manufacturer'sspecifications.

Walls. It is important that the walls of the

chamber be high enough to assist combustion, but

not so high as to interferewith the heat transfer

from the combustion products to the heat

exchanger.Figure 22 shows the height tobe used

based on the firing rate. The chamber wall should

be 2 to 2-1/4 times as high above the nozzle as it

is from the floor to the nozzle.

If the base of a heating unit has a tendency to

overheat, the walls should be 2-1/2 to 3 times the

height from floor to nozzle. This is sometimes a

problem in gravity type air duct systems or

boilers that have been converted from coal to oil.

Be sure to use insulation between the furnace and

chamber wall up to the top of the wall.

Space between the chamber wall and the heating

plant should be filled with an insulating material,

such as mica pellets--except in wet leg or wet

base boilers. Poor grade of backfill shortens

the life of the chamber, reduces the efficiency

at which the oil burns, and increases

combustion noise.

Burner Setting. The chamber must be installed

so that the oil can burn cleanly without impinging

on the floor and causing carbon to form. Figure

23 shows recommended inside dimensions. The

burner end cone should be installed 1/4" back

from the inside chamber wall. We recommend

that you install refractory fiber material around

the outside diameter of the burner end cone and

air tube. If insulating material is not available,

and chamber opening exceeds 4-3/8", burner end

cone set back must be increased. (See Figure 20.)

Soft Fiber Refractory. Refractories of low

specific heat and low conductivity (insulating)

will rise in temperature more rapidly from a cold

start and maintain a higher temperature during

steady operation of an oil burner. This will help

produce more complete combustion and increase

the heat transfer by radiation to the heat transfer

surfaces of the heat exchanger.

Tests by the National Bureau of Standards

comparing a hard brick chamber to a precast soft

chamber in the same boiler determined that

losses by radiation, conduction, convection and

incomplete combustion were 13.4% for the brick

and 8.6% for the precast. The difference was

equal to 8300 Btu's per hour in favor of the

precast. This amounts to a possible saving of 6%.

Another advantage of soft fiber refractories is the

fact that they cool down faster than hard refracto-

ries. This helps prevent nozzle overheating and

afterdrip. Also---since soft refractories store less

heat--off cycle heat loss is reduced. Examples of

soft refractory chambers are shown in Figure 21.

Many modern residential boilers have no

chamber, but often a target wall and/or a blanket

on the floor.

"A" = Usable air tube length.

Face

of Firebox

FIGURE 20 Air tube insertion

The burner head should be 1/4"back from the inside

wall of the combustion chamber. Underno circum-

stances should the burner head extend into the

combustion chamber. If chamber opening isin excess

of 4 3/8", additional set backmay be required. 15

FIGURE 21 Soft fiber refractorycombustion chambers

Although it is possible to obtain a relatively good

fire without a chamber, you should realize that a

properly sized and shaped combustion chamber

will substantially improve combustion, provide a

hotter flame, and reduce the amount of soot

accumulation associated with sta_ up and

shutdown. Large commercial burners are

frequently fired without a chamber, but with

small residential burners the chamber becomes

extremely important. Modern materials for

chamber construction reach operating tempera-

ture within 20 seconds after starting the fire,

causing heat to be reflected back into the oil

spra}; speeding up the conversion of liquid oil to

vapor, and making the flame smaller but hotter.

In genera_l,combustion temperatures of high speed

flame retention burners will be II'X)°Fto 200°F

higher tl-_nnon-flame retentionburners, even

though the same oil rate, same a_ fuel ratio and

same chamber are used. Some combustion

chamber manufacturers recommend either slightly

undeffiring burners or slightly oversizing chambers

when flame retentionhead burners are useA.

Youmay find some applicationswhereeconomics

recommendsthe installationof a flameretention

burnerwithoutthe chamberFor example,if a

customerh_ an obsoleterotary wall-flameburner

in his home andis unable toaffordthe replacement

of the boiler,a commonsolutionwouldbe to

remove the rotary burner, seal the hearth with

refractory cement, and install a flame retention

burner fired through the door. This type of installa-

tion would be far less costly than the more desirable

boiler and burner replacement which must eventu-

ally follow, but would permit the homeowner an

interim improvement.

While we have had much to say about the im-

proved combustion achieved through utilization of

a chamber, there are also some other benefits to be

considered. Chambers act as sound absorbers, and

this feature is highly desirable since some flame

retention burners have more intense flame noise

than the older burners they are replacing. Another

benefit obNned from combustion chambers is the

protection of those portions of the dry base boiler or

fumace which could not withstand prolonged

exposure to intense heat or the rapid heating-

cooling of the metal.

When the correct firing rate to match the heat

load has been determined, the proper size

combustion chamber should be selected to match

that firing rate. This will result in maximum

efficiency being achieved. The relation between

the size of an existing chamber and the determi-

nation of the correct firing rate to fit that chamber

is important, and should be considered whenever

the firing rate is altered.

0 Sq. In.

erGal,

90 Sq. In.

Per Gal.

100 Sq. In.

Per Gal.

Oil

Consumption

gph

.75

.65

1,00

1.25

1.35

1.50

1.65

2.00

2.50

3,00

3_50

4.00

4.50

5.00

5,50

6.00

6.50

7.00

7.50

8,00

8.50

9.00

9,50

10,00

11.00

12,00

13.00

14,00

15_00

16.00

17.00

18.00

Square

InchArea

Combustion

Chamber

100

108

120

132

160

200

240

315

360

405

450

Square

Combustion

Chamber

Inches

8x8

8.5 x 8,5

9x9

lOx 10

10-1/2 x 10-1/2

1t x 11

1t-1/2 x 11-1/2

12_5/8x 12-5/8

14-1/4 x 14-1/4 i

15-1/2 x 15-1/21

Die.Round

Combustion

Chamber

Inches

10-1/8

11-1/4

11-3/4

12-3/8

t4-1/4

17-1/2

2!-1/2

Rectangular

Combustion

Chamber

Inches

10 x 12

10x13

12 x16-1/2

13x 18-1/2

15x21

16 x 22-1/2

17 x 23-1/2

18 x25

Conventional

Burner

Widthx Length

5.0

5,0

5.0

6.5

7.0

7.5

8,0

8.5

9.0

Conventional

Burner

SingleNozzle

HEIGHTFROMNOZZLETO FLOORINCHES

Sunflower

FlameBurner

TwinNozzle

7.0

5.0

Sunflower

FlameBurner

SingleNozzle

5.0

5,0

5.0

6.0

7.5

8.0

8.5

9.0

9,5

10.0

6.5

7,0

7.0

7.5

8.0

8.5

9.0

9.5

10_0

10.0

10.5

11.0

11.5

12.0

12.5

13.0

14.0

14.5

15.0

15.5

16.0

550

600

650

7O0

750

800

850

900

950

1000

1100

1200

1300

1400

1500

1600

1700

1800

17-3/4 x 17-3/4

19x 19

20x20

21-1/4 x 21-1/4

23-1/2 x 23-1/2

24-I/2 x 24-1/2

25-1/2 x 25-1/2

26-1/2 X 26-1/2

27-1/4 x 27-1/4

28-1/4 x 28-t/4

29-1/4 x 29-1/4

30 x 30

31 x 31

31-3/4 x 31-3/4

33-1/4 x 33-1/4

34-1/2 x 34-1/2

36x36

37-1/2 x 37-1/2

38-3/4 x 38-3/4

40 x 40

41-1/4 x 41-I/4

42-1/2 x 42-1/2

::tO

20 x 27-1/2

2t x28_1/2

22 x 29-1/2

23 x30-1/2

24x31

25 x 32

25 x 34

25 x 36

26 x 36-1/2

26 x 38-1/2

28 x 29-1/2

28 x 43

29 x 45

31 x 45

32 x 47

33 x 48-1/2

34 x 50

35 x 51-1/2

9.5

10.0

10.5

11,0

1t .5

12.0

12.5

13,0

13.5

14.0

14,5

15.0

15,5

16.0

16.5

17.0

17.5

18.0

6.0

6_0

6.5

10.5

11.0

11.5

12.0

12,5

13.0

13.5

14.0

14.5

15.0

15.5

16.0

16.5

17.0

17.5

18.0

18.5

19.0

7.0

7,5

7.5

8.0

8,5

9.0

9.5

10.0

10.5

11.0

11,5

12.0

12.5

13.0

FIGURE 22 Combustion Chamber Sizing Data

23456

Length Dimension Suggested MinimumDia.

(L) (C) Height(H) VerticalCyL

FiringRate

(gph)

0.50

0.65

0.75

0.85

1.00

1.10

1,25

1,35

1.50

1.65

1.75

2.00

2.25

2.50

2,75

Width

(w)

4.0

4.5

5.0

5.5

6.0

FIGURE 23 Recommended minimum insidedimensions of refractory-type

combustion chambers

NOTES:

1. Flame lengths are approxi-

mately as shown in column 2.

Often, tested boilers or

furnaces will operate wel! with

chambers shorter than the

lengths shown in column 2.

2. As a general practice any of

these dimensions can be

exceeded without much effect

on combustion.

3. Chambers in theform of

horizontal cylinders should be

at least as large in diameter as

the dimension in column 3.

Horizontal stainless steel

cylindrical chambers should be

1 to 4 inches larger in diameter

than thefigures in column 3

and should be used only on

wet base boilers with non-

retention burners.

4. Wing walls are not recom-

mended. Corbels are not

necessary although they might

beof benefit to good heat

distribution in certain boiler or

furnace designs, especially

with non-retention burners.

HEAT EXCHANGERS

The next step in the operation of the heating

appliance is the transfer of heat energy from the

combustion gases to the air in the furnace or to

the water in the boiler. This is accomplished in

the heat exchanger, which is simply a wall which

keeps gases or liquids separated and allows heat

energy to flow out of the hot medium and into the

cooler medium. Heat is transferred in two ways:

I? Hot combustion gases directly contact the heat

exchanger surfaces and transfer heat.

•'Radiant energy in the combustion chamber

heats the heat exchanger surfaces (similar to

being heated by the sun). The selection of

wall material will depend on its ability to

easily pass heat, its cost, and several other

factors. This is a whole area of study in itself.

If the heat exchanger were a perfect transferer of

heat, all the energy in the combustion products

would be transferred to the distribution medium.

This would mean no losses of heat! With no heat

losses, the stack temperature would be reduced to

room temperature. Of course you know this is not

the actual case. Losses are caused by

!I' Temperature differences

•'Contact time

'It Insulation

The greater the temperature difference between

the combustion gases and the temperature of the

air or water to be heated, the more heat will be

transferred in a given time. There is very little

that can be done about the temperature of the air

or water to be heated, but if the temperature of

the combustion gases can be raised, more heat

would be transferred. This is another reason

why a high flame temperature from the burner

is desirable.

The longer the hot combustion gases are in

contact with the walls of the heat exchanger, the

more heat will be transferred. The scrubbing of

the heat exchanger walls by the combustion gases

is essential. This means that small flue passages

in the heat exchanger provide better contact

than wide open flue passages. With greater heat

exchanger surface area per volume of combus-

tion gas, more intimate contact of heat and

walls occurs.

Heat Exchanger Designs

Many types of heat exchangers--with varying

degrees of efficiency--are in use today. The

following are some major types:

Single-Pass, Vertical Tube

Exchangers (Boilers)

Hot gases flow through the boiler in only one

direction (up). (See Figure 24.)

Multi-Pass, Horizontal Tube

Exchanger (Boilers)

Hot gases flow upward--then change direction

and flow through horizontal tubes. (See

Figure 24.)

Oil Furnace Heat Exchangers

A typical oil furnace heat exchanger actually

consists of two exchangers. The hot gases first

enter the primary exchanger (inner cylinder), then

pass through a connector to the secondary

exchanger (outer cylinder). This provides

SINGLE-PASS,VERTICALTUBEEXCHANGER

\_ /

MULTI-PASS,HORIZONTALTUBE EXCHANGER

Heat Exchanger

Exhaust To Chimney

Boiler

Water

Gases

FIGURE 24 Heatexchanger designs

FIGURE 25 Oil furnace heat exchanger

prolonged gas/exchanger contact,

to capture more of the heat. (See

Figure 25.)

Condensing Furnace

Exchangers

Condensing furnaces have three

separate exchangers: the primary

exchanger, the secondary ex-

changer, and a condensing

exchanger which cools gases

below the dew point--converting

some of the water vapor into

water. This reduces water vapor

heat loss and raises furnace

efficiencies. (See Figure 26.)

Longer contact time can also be

achieved by reducing the amount

of combustion gases produced per

gallon of fuel burned or per period

of time. A smaller volume takes

longer to flow over heat exchanger

surfaces. Lowering the excess air

can reduce the volume of combus-

tion gases produced per gallon of

fuel burned and reducing the

nozzle firing rate can reduce the

Ai Handler

Heat Exchangers

Primary

3econdary

[ 11

Condensing

FIGURE26 Condensing furnace heat exchanger

lira Excess Combution Air

Cools the Combustion

Gases and Increases

_, Their Volume _Ikt

0 20 40 60 80 100

% Excess Combustion Air

FIGURE 27Approximate relationship of % excess air with flame

temperature and volume of combustion gases

11,000

io,ooo"6

t..-

9,000 _

._.9.

,8,000 {ff

{/)

7,000 -_

8,000 _

volume of combustion gases produced per unit of

time. Figure 27 indicates the relationship between

excess air and the flame temperature and volume

of combustion gases.

Insulation is any material that stops or slows

down the normal rate of heat transfer. Obviously,

you do not want to place an insulating material

between the combustion gases and the heat

exchanger walls. Smoke deposits (often called

soo0 act as an insulator! Smoke deposits from

smoky corr/bustion can collect on the heat

exchanger surfaces and reduce the effectiveness

of the heat transfer process. Estimates have

been made indicating that a 1/8 inch thick

coating of soot on heat exchanger walls has

the same insulating ability as a 1 inch thick

fiberglass sheet.

It should be understood at this point that smoke

caused by a poorly operating oil burner is a bad

thing, not only because the smoke represents

unburned fuel, but because .SmokeSoots up Heat

_er Surfaces and Prevents Transfer of

Heat to the Heating Load! A good burner helps

the heat exchanger be more efficient by:

YProviding combustion products at a high

temperature. This means a high flame

temperature.

'V' Providing combustion products which have a

low volume per gallon of fuel burned. This

means low excess air.

V Providing clean combustion products which

contain a minimum of smoke.

COMBUSTION AIR REQUIREMENTS

Buildings with Adequate

Air Infiltration

In many cases, a burner operating in an uncon-

fined space of a conventional frame, brick or

stone building will receive adequate air supply

from leakage in the building itself. But, if the

burner is located in a confined space such as a

furnace or boiler room, the enclosure must have

one permanent opening toward the top of the

enclosure and one near the bottom of the enclo-

sure. Each opening must have a free area of not

less than one sq. in. per 1,000 Btu per hour.

Another way to measure it is 140 square inches

per gallon per hour. Refer to NFPA 31.

Remember to take the total input of all air-using

appliances into consideration when figuring the

openings. The openings must connect with the

inside of the building, which should have

adequate infiltration from the outside.

As an example, if an oil burner was firing at 1.25

gph and a water heater was firing at .50 gph, each

opening in the enclosure should be 245 sq. in.

(1.25 gph + .50 gph = 1.75 gph, 1.75 gph x 140

sq. in. = 245 sq. in.) A 245 sq. in. opening would

typically be 10" x 25" or 16" x 16".

Buildings with Less than

Adequate Air Infiltration

If the burner is located in a tightly"constnacted

building where there is inadequate outside air

infiltration, outside combustion air must be

supplied by some other means.

One method to accomplish this is through a

permanent opening, or openings, in an exterior

wall. The opening, or openings, must have a total

free area of not less than one sq. in. per 5,000 Btu

per hour, or 28 sq. in. per gallon per hour. All

appliances must be taken into consideration.

Refer to NFPA 31.

Another method is to supply outside air directly

to'the oil burner through round, smooth duct

work. (See Figure 28.) Some burner manufactur-

ers offer accessories which allow outside

combustion air duct work to be coupled to the

burner; for example, the Field Controls CAS-2B

AirBoot TM (Beckett kit #51747). Consult the

burner manufacturer for the recommended kit.

The Beckett Model AF II burner allows outside

combustion air duct to be connected directly to

the bumer, without an accessory kit.

Outdoor Air

Ducted to Burner

FIGURE28 Outside air combustion

Residential system

The Tjernlund Combustion Air In-ForcerTM mechanically drawsoutside air indoors on demand to

providefresh airfor safe andefficientoperationof fuel burning equipment,withoutrequiringdirect

connectionto the appliances. The commercialsystemblendscoldair withambient roomair before

discharginginthe homeor building.

Courtesy el Tlemlund Products, In&

FIGURE 29 TjernlundCombustion Air In-ForcerTM

Draft

In the oilheat industry, the word "draft" is used to

describe the slight vacuum, or suction, which

exists inside most heating units. The amount of

vacuum is called "draft intensity". Draft volume,

on the other hand, specifies the volume (cubic

feet) of gas that a chimney can handle in a given

time. Draft intensity is measured in "Inches of

Water Column" (W.C). Just as a mercury

barometer is used to measure atmospheric

pressure in inches of mercury, a draft gauge is

used to measure draft intensity (which is really

pressure) in inches of water.

"Natural" draft is actually thermal draft, and

occurs when gases that are heated expand so that

a given volume of hot gas will weigh less than an

equal volume of the same gas at a cool tempera-

ture. Since hot combustion gases weigh less per

volume than room air or outdoor air, they tend to

rise. The rising of these gases is contained and

increased by enclosing the gases in a tall chim-

ney. The vacuum or suction that you call "draft"

is then created by this column of hot gases.

"Currential" draft occurs when high winds or air

currents across the top of a chimney create a

suction in the stack and draw gases up. "Induced

draft" blowers can be used in the stack to

supplement natural draft where necessary.

There are four factors which control how much

draft a chimney can make:

_' The height of the chimney--the higher the

chimney, the greater the draft.

Outside

Condition Inches W:C.

Winter start up

Winter operation

Fall start up

Fall operation

FIGURE 30 Exampleof draft changesinachimney

110

400

-.050

-.136

-.011

-.112

V Chimneys may not draft correctly due to

problems such as the following:

A. Chirvmey is too big (See Figure 32, page 24).

B. Breaks in the chimney liner.

C. An improperly constructed or damaged flue

system venting multiple appliances to a

common chimney (See page 24).

For a list of common chimney problems and

their solutions, see Figure 40, page 27.

'_' The weight per unit volume of the hot

combustion products--the hotter the gases,

the greater the draft.

V The weight per unit volume of the air outside

the home--the colder the outside air, the

greater the draft.

Since the outside temperature and flue gas

temperature can change, the draft will not be

constant. When the heating unit starts up, the

chimney will be filled with cool gases. After the

heating unit has operated for a while, the gases

and the chimney surface will be warmer, and the

draft will increase.

Also, when the outside air temperature drops, the

draft will increase. To indicate the effect of these

changes, the information in Figure 30 was

determined for a 20 ft.-high chimney. You can see

that the draft produced by this chimney could be

expected to vary from -.011 to -.136 inches W.C.

The high draft is over 12 times more than the low

draft. This large variation cannot be tolerated for

the following reasons:

'I' Too little draft can reduce the combustion air

delivery of the burner; which can result in an

increase in the production of smoke.

T Excessively high draft increases the air

delivery of the burner fan, and can increase air

leakage into the heating plant. This reduces

CO 2 and raises stack temperature, resulting in

reduced operating efficiency.

'_' High draft during burner off periods increases

the standby heat losses up the chirruley.

Because draft will not exist in any great amount

during a cold startup, the burner should not

depend on the additional combustion air caused

by draft. The best way to be sure the burner d_s

not depend on this air is to set the burner for

smoke-free combustion with a low overfire draft

(-.01 to -.02 inches W.C.). If a burner cannot

produce good smoke-free combustion under low

draft conditions, there is something wrong with

the burner or combustion chamber, and it should

be corrected. Using a high draft setting to obtain

enough combustion air for clean burning is like

depending on a crutch which is not always there.

A burner which gives clean combustion only

with high draft will cause smoke and soot any

time the chimney is not producing high draft.

In a previous section, we described the effect of

a]r leaks, and perhaps you now realize that air

leaks occur because of draft inside the heating

unit. It is easy to see that less draft will cause less

air leakage and produce a higher efficiency.

Therefore, sealing air leaks can aid in improving

heating appliance efficiency.

Draft Regulators

From the previous information, you should

realize that a constant draft is needed, and this

draft should be no more than that which will just

prevent escape of combustion products into the

home. Since natural draft as obtained from a

chimney will vary, it is necessary to have some

sort of regulation. The normal draft regulator or

"barometric damper" for home heating plants is

the so called by-pass or air bleed type as shown

in Figure 31. This type of regulator is simply a

swinging door which is counterweighted so that

any time the draft in the flue is higher than the

regulator setting, the door is pulled in. When the

damper is pulled open, room air flows into the

flue, which helps regulate the draft overfire, so

(hat it remains at the recommended level. If the

draft is less than the regulator setting, the

counterweight keeps the swinging door closed,

FIELD DRAFT CONTROLS

TYPE RC

Oil or Coal Residential

and Commercial

Calibratedto alloweasyadjust-

mentto furnace orboiler

manufacturer's specifications.

Designedfor settingsfrom .02"to

.08".It is sosensitivethat

instrumentationshouldbe usedfor

adjustments.

TYPE M

Oil or Coal Residential

Designedforsettingsfrom.01"to.l".

Recommendedfor oil or coal fired

residentialheatingapplications.

Featuresan infinitelyvariablescrew

adjustment,permittingan extremely

fine instrumentsetting.

TYPE M +MG2

Oil,Gas, Oil/Gas,or Solid Fuels

LargeResidential/Commercial

Compact,rugged,heavydutycontrol

for anyinstallationwith10"orlarger

diameterflue pipe.Adapts toany fuel.

Requiresonlythesimplest,on-the-job

adjustmentsdependingon fuel to be

utilized.

FIGURE 31 Field draft controls Illustrationscourtesy of The Field Controls Company

and only flue gas flows into the chimney. This

gives the highest draft possible under those

conditions.

It is important to understand that the function of a

draft regulator is to maintain a stable or fixed

draft through the heating equipment, within the

lirr&s of available draft from the chimney, by

means of an adjustable barometric damper.

Draft can be measured by using a draft gauge. It

cannot be estimated or "eye balled." The draft

should be checked at two different locations in

the heating appliance: (1) over the fire, which

indicates firebox draft condition, and (2) in the

breech connection.

1. Draft Over the Fire

With appliances designed for negative draft

operation, the draft over the fire is the most

important and should be measured first.

The overfire draft must be constant so that the

burner air delivery will not change. The overfire

draft must be at the lowest level which will just

prevent escape of combustion products into the

home under all operating conditions. Normally,

an overfire draft of -,0l" to -.02" W.C. will be

high enough to prevent leakage of combustion

products and still not cause large air leaks or

standby losses. If the overfire draft is higher than

-.02" W.C., the draft regulator weight should be

adjusted to allow the regulator door to open

more. If the regulator door is already wide open,

a second regulator should be installed in the stack

pipe and adjusted. If the draft is below -.01"V_.C,

the draft regulator weight should be adjusted to

just close the regulator door. Do not move the

weight more than necessary to close the door.

Never wire or weight a regulator so it can never

open. There may be times when the outside air is

colder, or the chimney hotter, or high wind is

affecting draft, and the draft needs regulation.

The overfire draft is also affected by soot buildup

on heat exchanger surfaces. As the soot builds up,

the heat exchange passages are reduced, and a

greater resistance to the flow of gases is created.

This causes the overfire draft to drop. As the

overfire draft drops, the burner air delivery is

reduced and the flame becomes even more

smoky. It is a vicious cycle which gets increas-

ingly worse. Note: Some systems are designed

for positive pressure overfire. Consult the

manufacturer's specifications for draft and

venting requirements.

2. Breech or Stack Draft

After the overfire draft is set, the draft at the

breech connection should be measured. The

breech draft will normally be slightly more than

the overfire draft because the flow of gases is

restricted (slowed down) in the heat exchanger.

This restriction, or lack of it, is a clue to the

design and condition of the heat exchanger. A

clean heat exchanger of good design will cause

the breech draft to be in the range of -.03" to -.06"

W.C. when the overfire draft is -.01" to -.02" W.C.

Flue and Chimney Exhaust

1. Flue Pipe

The flue pipe should be the same size as the breech

connection on the heating plant. For modem oilheat

units, this should cause no problem in sizing the

flue pipe. The sizes generally are 4" to 6" under

1 gph, 7" to 1.50 gph, and 8" for 1.50 to ZOOgph.

The flue pipe should be as short as possible and

installed so that it has a continuous rise from the

heating plant to the chimney. Elbows should be

minirrfized, and the pipe should be joined with

metal screws and supported with straps where

needed.

The draft regulator should be installed in the flue

pipe before it contacts the chimney and after the

stack primar 7 control, if one is used. Make sure

the draft regulator diameter is at least as large as

the flue pipe diameter.

2. Chimney

Figure 32 shows recommended size and height

for chimneys based on Btu input. Consult

manufacturer's specs and NFPA 31. See Figure

40, page 27 for chimney troubleshooting tips.

GrossBtuInput RectangularDim. RoundDim. MimimurnHeight

144,000 8 112"x 8 1/2" 8" 20 feet

235,000 8 1/2" x 13" 1O" 30 feet

374,000 13" x 13" 12" 35 feet

516,000 13" x 18" 14" 40 feet

FIGURE 32 Common chimney sizes vs. Btu input

10' ortess

6" flue

Boiler/

Furnace

(higher

gph)

The larger appliance firing rate enters the chimney below

the smaller appliance firing rate.

FIGURE 33 Multiple appliances vented separately

Venting Multiple Appliances into

a Common Chimney or Flue

Connecting more than one oilheat appliance to a

common chimney can be easy and beneficial

once you understand the basic guidelines:

1. Always follow the appliance manufacturer's

recommendations on venting the particular

appliance, and obey local codes and require-

ments.

2. The chimney must be of adequate size to

properly vent the gases created by the total

Btu input of all appliances combined.

3. The flue piping, whether for single or multiple

appliances, should be as short a run as

possible, and rise I/4" per running foot up and

toward the chimney. Whenever possible, do

not exceed 10 feet of flue pipe length.

4, Avoid using more than two 90-degree turns in

the piping. Additional 90-degree turns

excessively restrict the exhaust system at

burner start-up.

5. The piping, when inserted into the chimney

entrance, should not extend beyond the inside

surface of the chimney liner. The area around

the flue piping should be sealed where it

enters the chimney.

6. When venting two appliances separately into

a common chimney, always install the smaller

flue pipe (appliance with lowest gph input) at

a higher point into the chimney than the larger

flue pipe for the appliance with the largest

gph input (Figure 33).

Basic Requirements

To determine the main flue size or manifold

required to vent more than one appliance into the

chimney, you combine the flue sizes of the

individual appliances. Example: If you combine a

furnace or boiler (8" flue) with a water heater (6"

flue), refer to Figure 34 for sq. in. area of each

individual flue size, and total the two areas.

6" flue = 28.27 sq. in.

8" flue = 50.27 sq. in.

TOTAL = 78.54 sq. in.

Refer to Figure 34 to determine the pipe diameter

the total area corresponds with. In our example,

78.54 sq. in. calls for a 10" diameter pipe. The

main flue or manifold required to properly vent

these two appliances is a 10" diameter pipe.

Whetheryouarecombiningtwoappliancesor

more,youwillfollowthesamemethodof

totalingindividualfluesizestodetermineyour

mainflueormanifold.

Common Systems

Figures 35 and 36 show the most common types

of multiple appliance venting systems the

tapered manifold system and the constant sized

manifold system.

When determining the sizing for the tapered

manifold system (Figure 35), size each section

according to the combined input of the appli-

ances that vent through that section. The section

furthest from the chimney vents only one

appliance. The middle section vents two appli-

ances. The section closest to the chimney vents

three appliances.

Damper Locations

Finally, you should also be familiar with proper

barometric damper locations. Figure 37 provides

this information.

ALTERNATIVE VENTING SYSTEMS

In some cases, existing chimneys may be

inadequate----or there may be no chimney at all

(e.g., electric-to-oil conversions). Constructing a

new chimney may be difficult. In these cases,

alternative venting methods may be called for.

Power Chimney Venting

Sometimes an otherwise inadequate chimney can

do the job with the help of a power draft inducer.

(See Figure 38.)

This consists of a vent fan placed in the flue pipe,

or at the top of the chimney, to create an "artifi-

cial" draft. If the fan is located in the flue pipe,

the portion of the pipe between the fan and the

chimney is under a positive pressure--which

requires that portion of the pipe to be tightly

sealed to prevent escape of flue combustion gases

into the home.

A metal chimney liner and condensate drain may

be required to prevent damage to the chimney.

Side-Wall Venting

If no chimney exists--or the existing chimney

cannot be used, even with a liner---_.heonly

solution may be to vent through the wall

(Figure41).

Side-wall venting systems eliminate the need for

a chimney. One way to side-wall vent, power

venting, utilizes an induced draft fan, which

provides the draft required to exhaust the

combustion products through a side wall. This

system normally requires an air-flow proving

switch to confirm that the required draft is

present before combustion begins. Another way

is direct venting, without an induced draft fan.

With both types of systems, discharge fittings are

designed to pass through combustible walls and

minimize the effects of wind on the venting of

the combustion products. Burner, appliance, vent

system and controls must be considered as a

system, not just independent parts pieced together.

Flue Diameter Equiv.Sq.In, Area

3" 7.06

4" 12.56

5" 19.63

6" 28.27

7" 38.48

8" 50.27

9" 63.62

10" 78,54

Flue Diameter Equiv.Sq. In. Area

11" 95.03

12" 113,10

13" 132,73

14" 153.94

15" , 176.71

16" 201.06

17" 226.98

18" 254.471

FIGURE 34 Square inch area of flue collars

-" 7" 6"

U.II1 "U.,'_2-- _"tjn_l 3"

....ola j

i i l_ PRE-FAa CHIMNEY

_l _" co...cTio.

Ea,ctt _on sL__:_ to h;/ilcJle It_mt Ot ¢omb_nalJon of

,a_p_l,_',c6'.sattac_e_

FIGURE35 Tapered manifold vent system

i©

I7" 7" 6"

Unll 1 Unit 2 Unit 3

Mlnlfold

PRE-FAB CHIMNEY

CONNECTION

E_t6re m_tfold suff_tty t al"ga for a_l

a_'_,:Fsan_ _et as _mtr_ vent

FIGURE36Constantsizedmanifoldventsystem 25

Benefits

The first benefit of a side-wall venting

system is that it eliminates the need for

a chirrmey. This can result in potential

savings in new home construction.

There is also the opportunity to retrofit

chimneyless (i.e., electrically heated)

homes.

The second benefit is the potential for

increased efficiency. Condensation of

acids in the flue gases occurs when the

flue gas temperature drops to about

200°E The minimum recormnended

gross stack temperature at the breeching

is usually 500°F-550°F with conven-

tional appliances, so that as the flue

gases are cooled in the chimney, the flue

gas temperature does not fall below the

acid dew point.

In the side-wall vented system, flue

gases are not cooled in a chimney. Heat

that is typically test in the chimney can

be extracted in the heating appliance,

dropping the gross stack temperature to

300°F-350°E This raises the steady state

efficiency. (See Figure 39.)

Acid will not condense in the short side-

wall duct; water vapor won't either.

Keep in mind that water vapor in the

flue gas will condense if flue gas

temperatures drop below about 120°E

Make sure, however, that you are

operating at the 300°F-350°F gross

stack temperature with power side-wall

venting only when the manufacturer has

designed or approved his furnace or

boiler for this arrangement. However,

the advantage of chimneyless construc-

tion and the reduction of exhaust gases

to a safe 200°F-300°F range without a

special high efficiency appliance can

often be accomplished by dilution of the

flue gases via a barometric damper

upstream of the induced draft fan.

Concerns

Safety concerns are of primary impor-

tance with any heating system and

should be with side-wall vented

applications. As previously stated, air

flow proving switches are typically used

1©

-1 I

IUnit

When venting multiple _koplianses, it is best to use a draft control for each boiler, Locate the barometric

damper between the appliar_e outlet and the main manifoTd-Location *AL When his uptake is too

short to permit the installation of a control k_,.,ateaseperate control for each appliance On the main

manifold as iUustrated in Local° "B',

FIGURE 37 Barometric damper locations when venting

multiple appliances

Existing Chimney..,

Backfill Insulation -- •

Reduced Diameter

Stainless Steel Liner- --

(Optional)

Power Vent

(Induced Draft) .

IF--'li out_

Boiler or It II ]T-

Furnaoe tL--JI C°ndensat_tL_

_ D_ain_

FIGURE 38 Power chimney venting system

EFFICIENCY VS, NET STACK TEMP.

No. 2 Fuel Oi1,12% C02

ILl

200 300 400 500 600 700

NET STACK TEMP. *F

26 FIGURE 39 Efficiency vs. net stack temperature

Fireplace

Ash Dump

for

Fireplace

FIGURE 40 Common chimneytroubles

and theircorrections

Troubles

Topofchimneylower

thansurroundingobjects.

Chimneycaporventilator,

Copingrestrictsopening.

Obstructionin chimney.

Joist projectinginto

chimney.

Examination

Observation,

Observation.

Can be foundby

lightandmirror

reflecting

conditionsin

chimney.

Loweringa light on

extensioncord,

Corrections

Extendchimneyabove

allobjectswithtn30feet.

Remove.

Makeopeningaslargeas

insideofchimney.

Useweighttobreakand

dislodge.

Mustbehandledbya

competentbrickcontractor.

Breakin chimneylining.

Collectionofsootat

narrowspaceinflue

opening.

Offset.

Twoormoreopeningsinto

samechimney,

Loose-seatedpipeinflue

opening.

Smokepipeextendsinto

chimney.

Failureto extendthe

engthof fluepartition

:othe floor.

Loose4ittedclean-out

door

Smoketest--bui!d Must_ handledbya

smudgefireblocking

offotheropening,

watchingforsmoke

to escape.

Lowerlighton

extensioncord.

Lowerlighton

extension.

Foundby inspection

frombasement.

Smoketest.

Measurementof

' pipefrom withinor

observationof pipe

by meansof a

loweredlight.

Byinspectionor

smoketesL

Smoketest.

competentbrick

contractor.

Cleanout withweighted

brushor bagof loose

gravelonendof line.

Changeto straightorto

longoffset.

Theleastimportant

openingmustbeclosed,

us=ngsomeother

chimneyflue,

Leaksshouldbe eliminated

bycementingall pipe

openings.

Lengthof pipemustbe

reducedto allow endof

pipeto be flushwith

insideof tile.

Extendpartitionto

floor level.

Closeall leakswith

cement.

to ensure proper draft from the induced draft fan.

Temperature sensing switches can be utilized as

backup protection for a blocked vent condition.

Side-wall fittings must be designed for walls

constructed of combustible materials. The side-

wall presence of flue products at 200°F-300°F

must be considered.

Reliable operation is a second concern. Wind

direction and velocity can have a great impact on

a side-wall exhaust vent and must be considered

both in system design and in installation. A

closed air system with outside intake on the same

wall as the exhaust vent will tend to reduce this

problem. Clean burner operation is critical to

Power Side-Wall Venting Power Side-Wall Venting

( With Outdoor Fan )

FIGURE 41 Power side-wall venting

avoid fume and staining problems, Corrosion due

to stack temperatures being too low (and resultant

condensing) must be prevented.

There are also local building code requirements

that restrict the installation of side-wall vent

systems. Industry progress is being made in this

area, but check local/state building code require-

ments before planning a side-wall vented

installation.

Field Power Venter Model SWG

Combinesfan,motor,andventhoodintoonecomplete,

compactunitthatseasilyinstalledoutsidethebuilding,so

noiseandvibrationarevirtuallyeliminatedfromtheoccupied

areas.Ventingwithnegativepressure,theSWGprevents

possiblefluegasleakagefromtheventingsystem.

FIGURE 42 Field power venter

Sealed Combustion Furnace

Sealed Combustion Boiler

FIGURE 43 Direct side-wall venting and outside combustion airwhich features the BeckettAFII orAFG.

Power Venting

In this type of system, a power draft inducer fan

is used as with power chimney venting. However,

the gases are vented through the wall rather than

up a chimney. If the fan is inside the house, any

portion of the system between the fan and the

outside vent is under a positive pressure and must

be carefully sealed to prevent gases from leaking

into the house. Also required, is a safety control

to shut off the burner if the power venting system

malfunctions.

Direct Venting

Modem high-speed burners sometimes provide

enough positive pressure to exhaust gases

through the wall (or up a chimney) without the

use of a power fan. Since positive pressure is

present throughout such a system, careful sealing

is required to prevent leakage of gases into the

house.

Sealed Combustion

When side-wall venting is combined with a

sealed (or balanced) outside combustion air

supply, the result is sealed combustion. This is

highly recommended with side-wall venting. (See

Figure 43.)

Outdoor Units

When the appliance itself is outside the home,

no chimney or venting system is required,

and adequate combustion air is assured. (See

Figure 44.)

All venting (including alternative venting

systems) should be per the appliance

manufacturer's recommendations, and in

compliance with all jurisdictional codes,

Outdoor Appliance Installation

_ xhaust

Vent

Outdoor

Unit

Enlosure

FIGURE44 Outdoor applianceinstallation

%DEFINITION OF

VARIOUS TYPES OF

EFFICIENCY

When the word efficiency is used, do you know

what is meant? By definition, efficiency is a

measure of how well something is produced as

compared with what went into producing it. In

terms of heating systems, efficiency is a measure

of how well energy is transferred from one form

or place to another form or place. In general, the

energy output of a machine or device is compared

with the energy input:

useful energy output

Efficiency =

total energy input

For residential heating appliances, the measure-

ment of efficiency can be confusing, as there are

several different efficiencies that can be dis-

cussed. Because of this, it is important to

distinguish between the different efficiencies and

understand the specific meaning of each.

COMBUSTION EFFICIENCY

Combustion efficiency characterizes the effec-

tiveness of the combustion process in converting

the chemical energy of the fuel to heat. You may

be surprised to learn that the combustion effi-

ciency of oil burners is quite high--usually 98 to

100 percent. This means that almost all of the

chemical energy available in the fuel is changed

into heat energy of the combustion products,

Even in the case of a smoky flame, the amount of

energy lost because of unburned carbon is very

low. In fact, even with a smoke number of 9, the

amount of energy lost is found to be about 0.1

percent.

At this point, you may be wondering why so

much attention is given to the proper operation of

the burner if it does an almost perfect job of

getting the heat energy out of the fuel. Also, you

may be thinking that if there is such a small

amount of energy lost due to smoke generation,

why worry about it. If these thoughts have

occurred to you, it is recommended that you turn

back to page 20 and reread the paragraph with the

underlined words. This should explain the

concern over smoke generation.

Combustion efficiency =

heat energy in the combustion gases

chemical energy in the fuel

STEADY-STATE EFFICIENCY

Steady-state efficiency is the effectiveness of the

heating unit in extracting heat from the chemical

energy in the fuel and transferring it to the

medium (air, water, or steam) used for space heat

when the entire system is operating in a steady-

state mode. This is the efficiency you are most

familiar with---one that can be easily approxi-

mated by measuring the net stack temperature

and the CO2 or 0 2 percent of the flue gases.

Measuring this efficiency requires that the

heating appliance has been operating long enough

so that steady-state (effectively unchanging)

temperatures have been established throughout

the system. In other words, the system must be

thoroughly warmed-up. As you are aware, steady-

state efficiencies are typically between 65 and 85

percent.

Steady-State Efficiency =

steady-state heat removal rate

to transfer medium

steady-state chemical energy

input rate

AFUE RATINGS

In order to assist the consumer in purchasing

heating appliances that conserve energy, the

Department of Energy (D.O.E.) has established

test procedures and Annual Fuel Utilization

Efficiency ratings (AFUE). This information is

presented on uniform rating labels for similar

appliances, and the annual operating costs are

estimated for comparison purposes.

The efficiency ratings of appliances are beneficial

for the informed homeowner, and industry also

uses them as a valuable tool. Many times the

contractor is asked for his recommendation of the

most energy efficient heating unit. He appreciates

that there is more involved than mere numbers.

Theseratingsmightbecomparedtothemileage

ratingsforautomobiles.The"steady"highway

drivingMPGratingisalwayshigherthan the city

or "average" driving MPG rating.

In both instance the AFUE and MPG ratings were

obtained under very carefully controlled labora-

tory conditions. There are important reasons why

the actual fuel consumption experienced in the

field will be slightly higher.

There are many variables that occur throughout

the heating season that can impact on the overall

system efficiency. Some are: changes in draft,

fuel, combustion air resection (due to lint, dust,

pet hair, etc.), temperature reduction in oil and

air, inadequate fresh air supply, and other subtle

environmental factors.

Experienced contractors view the AFUE ratings

as a valuable tool for comparison purposes,

but they do not attempt to set the burner to

operate at the 120 2 and smoke levels that were

used in the D.O.E. controlled laboratory

procedures. Real world conditions require that

consideration be given to the variable environ-

mental effects. Therefore, effective safeguards

are factored into the final burner adjustments,

discussed on page 46 of Chapter 5.

There is a very small premium to pay for the

added margin of air that will help keep the heat

exchanger clean throughout the full heating

season. How much would have been lost in real

dollars if the appliance had gradually become

sooted, losing efficiency until it required prema-

ture servicing?

Obviously, the efficiency ratings have an impor-

tant role to play. However, there must be a

balance between maximizing efficiency with

little or no margin for variables, and practical

field set-ups that have a reasonable amount of

reserve air built in. These methods are field-

proven and can help reduce nuisance, efficiency

robbing soot-ups.

MEASUREMENTS

This chapter covers the proper use of instruments

to measure the steady state efficiency of residen-

tial oil-fired heating appliances. Since you should

now understand what factors influence high or

low efficiency, effective use of these instruments

can aid you in improving the steady-state

efficiency of oilheat equipment. Perhaps you are

accustomed to adjusting burners by judging the

flame by eye or following a series of"rules of

thumb." Certainly, using these procedures can

work some of the time! But, would you stake

your reputation on it? What you are doing is

similar to a doctor diagnosing an illness without

the use of a stethoscope or an auto mechanic

tuning a car without the proper diagnostic

equipment. It is risky business!! Do yourself a

favor, make your job easier, and assure yourself

of leaving a heating system in good operating

condition by properly using the instruments

discussed in this chapter.

Stack Loss Theory

In Chapter 3, you learned that the steady-state

efficiency is a measure of the effectiveness of the

heating unit in extracting heat from the chemical

energy in the fuel and transferring it to the

distribution medium. Therefore, the most

straightforward approach to measuring the

steady-state efficiency would be to measure the

heat transferred to the distribution medium and

the chemical energy in the fuel, and then calculat-

ing the efficiency from these values. Unfortu-

nately, in a residential oilheat system, it would be

very difficult to measure the actual amounts of

heat energy in the fuel and the heat transferred to

the air, water, or steam. As an alternative ap-

proach, a simpler method, the "stack loss"

I Heat Energy

Input

,, 140,000 Btuh

method of efficiency measurement, is used.

The stack loss method is based on three

assumptions:

1. All the chemical energy in the fuel is con-

verted to heat energy. As was pointed out on

page 32, this is essentially accurate for all

burners as the combustion efficiency is

normally 98 to 100 percent.

2. The chemical energy per unit of fuel is the

same_140,000 Bttu'gal. This means that from

one shipment of fuel to another, variations in

chemical composition that affect the chemical

energy per unit of fuel oil are ignored. This

can lead to small errors in the stack loss

method.

3. The heat energy goes to one of two places:

•'The heating load or

•'Up the chimney

These assumptions are shown in Figure 45. From

this figure, it can be seen that by measuring the

heat loss up the flue and assuming an average

value for the heat energy in the oil, you do not

have to measure the heat transferred to the

distribution medium. Fortunately, measuring the

stack losses is not complicated. However, this

assumes that there are no jacket losses. In other

words, no heat is transferred through the walls of

the heating plant. From your experience, you

should know this is inaccurate and that in older,

largely un-insulated units, the jacket losses can be

significant. As a result, the stack loss method

tends to give higher efficiencies than those which

really exist.

Heat Energy to Load

119,000 Btuh

itl

FURNACE

Heat Energy Loss1

up chimney I

(Stack Loss) I

21,000Btuh I

Heat to Load = Heat Energy Input - Stack Loss

FIGURE45 Distributionof heatasdeterminedbythestacklossmethod

To measure the heat lost through the flue and

chimney you must:

V Determine the amount of the combustion

gases per gallon of fuel oil burned.

V Determine how much the combustion gas

temperature was changed (the difference

between the temperature at which the fuel and

air entered the burner and the temperature of

the combustion gases).

You should measure the amount and temperature

of the combustion gases at an identical point in

the flue pipe.

In Chapter 1, you learned how changes in volume

of excess combustion air affect the heat ex-

changer efficiency. As you might imagine, these

changes in volume of excess air per unit of fuel

burned also affect the weight of the combustion

gases formed from each gallon of fuel burned.

Since knowledge of the percent excess air enables

you to determine the weight of the combustion

gases per gallon of fuel burned, and since the

percent excess air can be determined by measur-

ing the percent carbon dioxide or oxygen, you

can determine the weight of combustion gases per

gallon of fuel burned by knowing the percent

carbon dioxide or oxygen.

Let's look at an example to make this more

clear. In Figure 3, page 3, we showed that

theoretically for every pound of fuel oil,

exactly 14.36 pounds of air are required to

completely burn the fuel. This was assum-

ing that there was perfect mixing and that

all the carbon and hydrogen in the fuel

combined with the oxygen in the air to

form carbon dioxide and water vapor. The

figure also showed that exactly 3.16 pounds

of carbon dioxide or 15.3% of the products

were formed if this "perfect" situation

occurred. On page 5, Figure 4, we showed a

typical case for which excess air was

needed to ensure that most of the carbon

and hydrogen in the fuel would combine

with oxygen to form the products. From

Figure 4, you can see that the same weight

(3.16 pounds) of carbon dioxide is formed,

but that this represents only 10.2% by

volume of the combustion products. So, by

measuring the percent carbon dioxide, you not

only can determine how much excess air exists,

but also you can determine the weight of com-

bustion products flowing up the flue pipe.

Oxygen measurements can also be used to

determine the amount of excess air and, in turn,

the amount of CO 2 in the flue gas. There is a

direct and fixed relationship between the amount

of CO 2 and 02 in the flue gas as shown in Figure

46. This figure indicates that as the percent CO 2

increases, the percent 0 2 decreases in the flue

gas. When testing for efficiency, we try to obtain

a low 0 2 reading or high CO 2 reading (in both

cases, low excess air).

Now we have one-half of what is needed to

determine the losses up the stack. The second half

is much easier. This is the temperature difference

between the fuel and air going into the burner and

the flue gases coming out of the heat exchanger.

The fuel and air will normally enter the burner at

about the temperature of the room in which the

furnace or boiler is located. The temperature of

the gases in the flue will vary from unit to unit

but can be measured with a therrnometer. The

difference between the flue gas temperature and

the fumace/boiler room temperature is called the

NET STACK TEMPERATURE.

15.3

o,,I

012 16 20

Percent Oxygen

FIGURE 46 Theoretical combustion relationship

between CO2 and 0 2 for #2 heating oil

20,9

FIGURE 47 CO2 gas analyzer

15 /rll

14 ....... /rt

13 J

° / ,/V

°/,4,

€

4 i

40 45 50 55 60 _ 70 75 80 85 90

Percent Efficiency

FIGURE 48 Graph of heating appliance efficiency

Once you know the percent CO 2 or

oxygen and the net stack temperature,

you can determine the steady-state

efficiency based on the stack loss

method. Remember that the stack loss

will be determined per gallon of fuel oil

burned, since this is how the weight of

the combustion gases was measured.

Because of this, you don't have to

measure the fuel input into the burner.

Since we assumed that each unit of fuel

oil (a gallon) contains the same amount

of chemical energy (140,000 Btu's), the

stack loss calculated will be per each

140,0¢_ Btu's of input energy. If we

subtract this percentage loss from 100%,

what remains will be the steady-state

efficiency. Rather than make you go

through the calculations to determine this

value, an efficiency chart or table can be

used which will give you the efficiency

based on the percent carbon dioxide and

net stack temperature. Many of you may

be familiar with the Bacharach Instru-

ment Company's Fire Finder Efficiency

Chart. You can also use other tables or

graphs to determine the steady-state

efficiency. Examples are shown in

Figures 48 and 49.

Now that you know what to measure and

why, let's turn our attention to how to

properly measure for steady state

efficiency. As a minimum, you need to

measure both the percent carbon dioxide

or oxygen, and the net stack temperature,

but, to get the complete picture and to do

the job right, smoke and draft measure-

ments are also required.

RGURE 49 No. 2 fuel oil efficient-t table

Net Stack Temp. oF

%02 200 250 300 350 400 450 500 550 600 650 700 750 800 _02

1 89.6 88.4 87.3 86.2 85.1 84.0 82.9 81.7 80.6 79.5 78.4 77.3 76.2 14.7

2 89.4 88.2 87.0 85.9 84.7 83.6 82.4 81,2 80.1 78.9 77.7 76.6 75.4 14.0

3 89.2 87.9 86.7 85.5 84.3 83.1 81.9 80.7 79.4 78.2 77.0 75.8 74.6 13.2

4 88.9 87.7 86.4 85.1 83.8 82.6 81.3 80.0 78.7 77.5 76.2 74.9 73.6 12.5

5 88.7 87.3 86.0 84.6 83.3 82.0 80.6 79.3 i77.9 76.6 75.3 73.9 72.6 11.7

6 88.4 87.0 85.5 84.1 82,7 81.3 79.9 78.577.0 75_6 74.2 72.8 71.4 11.0

7 88.0 86.5 85.0 83.5 82.0 80.579.0 77.5 76.0 74.5 73.0 71.5 70.0 10.3

Measurement of

Carbon Dioxide or Oxygen

Historically, to deterroJne the weight of the

combustion gases per gallon of fuel oil burned,

carbon dioxide has been measured with equip-

ment like that shown in Figures 47 and 50. This is

a rugged, inexpensive, and easy-to-operate

device. However, if you recall from Chapter 1,

the percent oxygen also can be used to detenmne

the weight of the combustion gases. There are

devices that measure oxygen rather than carbon

dioxide percent for the determination of steady

state efficiency, but let's turn our attention to the

most common device first---CO 2 analyzers.

Bacharach Instrument Company manufactures a

carbon dioxide analyzer called "Fyrite", which is

the most well-known instpament on the market.

The Fyrite (shown in Figures 47 and 50) and

other similar instruments work on the following

principles:

_' Chemical absorption of a gas sample by a

liquid chemical absorbent.

V Chemical absorbing fluid is also used as

indicating fluid.

The Fyrite analyzer contains potassium hydrox-

ide, a liquid with a capacity to absorb large

amounts of carbon dioxide. The Fyrite consists of

two main parts---sampling pump and analyzer.

The sampling pump consists of:

_' A metal sampling tube which is inserted into

the flue gases

•'A yarn filter and water trap which stops soot

and water droplets from entering the analyzer

I' A sample pump--a rubber bulb with a suction

valve and a discharge valve. These valves are

rubber flapper check valves which allow flow

in only one direction

Y A rubber connector which seals the sampling

pump system to the analyzer

The analyzer is molded of clear plastic containing

top and bottom reservoirs and a center tube

connecting the two reservoirs. The bottom of the

lower reservoir is sealed off by a flexible rubber

diaphragm which rests on a perforated metal

plate. The upper reservoir is covered by a molded

plastic cap which contains a double-seated

plunger valve. A spring holds this valve

against a finished seat in the top cap providing

a seal which makes the instrument spill-proof

in any position. When the valve is fully

depressed, it vents the top reservoir to the

atmosphere and seals the center tube beneath

it. When the valve is partially depressed, the

entire instrument is open to the atmosphere.

The bottom reservoir is filled with the absorb-

ing fluid which extends about 1/4 inch into the

bore of the center tube when the instrument is

held upright. The scale, which is mounted to

one side of the center tube, is movable so that

before each test the scale may be conveniently

adjusted to locate the zero scale division

exactly opposite the top of the fluid column in

the center tube.

To measure the amount of CO 2 in a gas

stream, you must measure a known volume of

gas, bring the gas into contact with the

absorbing solution, and measure the loss in

volume after the CO 2 is absorbed. To accom-

plish this, you must first prepare the instrument

for sampling by purging the solution and

adjusting the scale so that the zero mark is

level with the liquid level. Be sure of the

following:

36 FIGURE 50 Construction of CO2 analyzer

V Allow instrument to reach room temperature.

If you have just come in from the cold

outdoors, place the Fyrite in a warm location

such as near the boiler or furnace. Make sure

it is not too hot, and don't forget to remove

the instrument.

Y Make sure sufficient liquid is in the reservoir.

If the liquid level is low, add water to the top

of the reservoir and depress plunger valve.

Repeat until scale can be adjusted to the

height of the liquid level.

Zero the instrument by turning the Fyrite upside

down at least twice, forcing the gas within the

reservoir to bubble through the liquid; then

upright and depress the plunger valve fully. After

five seconds (or some other known time interval),

adjust the zero mark on the scale to the liquid

level. The instrument is now ready for sampling.

Liquid may continue to drip down the bore of the

lower reservoir causing the liquid level to rise

above the zero mark on the scale. Do not readjust

the scale.

To make a test with the Fyrite, the metal sampling

tube at one end of the rubber hose is inserted into

the gas to be analyzed. Then, the connector plug

at the other end of the rubber hose is pressed

down on the spring-loaded valve at the top

reservoir. This seals off the center bore. Next, a

sample of the gas is pumped into the top reservoir

by stroking the rubber bulb. At least 18 bulb

strokes should be used to assure that the rubber

hose and the top reservoir are thoroughly purged

of the previously analyzed sample. (It doesn't

matter if you "over squeeze" just as long as you

compress the bulb a minimum of 18 times.) On

the last bulb stroke, the finger is lifted from the

connector plug which automatically returns the

plunger valve to upper position against its top

seat. With the valve in this position, 60 cubic

centimeters of the gas sample are locked into the

Fyrite and the top reservoir is opened to the

center bore so that the gas sample can pass to the

absorbing fluid. The Fyrite is then turned over,

forcing the gas sample to bubble through the

absorbing solution which absorbs the CO2. This

is repeated two additional times. The instrument

is then turned back and held upright again. After

five seconds (or the same time interval used when

zeroing the instrumen0, read the scale adjacent to

the liquid level. This is the carbon dioxide

percent in the gas sample. Record this value on a

data sheet.

The reason the liquid level will rise is because the

absorption of CO 2 by the absorbing fluid creates

a suction in the lower reservoir which causes the

diaphragm at the bottom to flex up. This, in turn,

pe_ts the level of the absorbing fluid to rise in

the center tube an amount equal to the CO 2

absorbed.

There is an easy check to determine if the

strength of the absorbing solution is weakening

and needs replacement. After you've completed a

measurement and recorded the CO 2 value, turn

the Fyrite over an additional two times forcing

the gas sample to bubble through the absorbing

solution. Return the analyzer to the upright

position and read the CO 2 percent (after the same

interval of time used before). If this value is

greater than the recorded CO 2 percent, it is likely

that the absorbing solution is weak and is not

absorbing CO 2 at its normal rate. Replace the

absorbing liquid before using the analyzer for

further measurements. Refer to the

manufacturer's instrnctions for the proper

procedure on filling the analyzers.

Also, there is an easy check to determine if the

sampling tube is leaking. Place your finger over

the end of the connector plug and squeeze the

bulb. If the bulb remains deflated and does not

refill with air, the sampling tube is leak-free.

Bacharach Instrument Company also manufac-

tures an oxygen Fyrite that operates on the same

principle but uses a fluid that absorbs oxygen.

The CO2 analyzer is more widely used and the

absorbing liquid is good for approximately 300

samples; the oxygen fluid is only good for about

100 samples. The use and operation of the 0 2

analyzer is identical to the procedure followed for

CO2. The only difference is in checking the

absorbing strength of the fluid. To determine the

absorbing strength of the 0 2 analyzer, pump a

sample of room air into the analyzer and measure

the 0 2 content. It should read 21 per cent. If it

reads less, you should replace the liquid.

Alternative Measurement

Techniques

Lynn Combustion Efficiency Analyzers.

Lynn Products Company manufactures a line of

Combustion Efficiency Analyzers that measure

0 2, flue temperature and smoke level. The

instruments employ an electrochemical oxygen

sensor that produces a small electrical current

proportional to the level of oxygen. The signal is

then amplified through a solid state electronic

amplifier and displayed either on an analog type

meter, which has I/2% oxygen scale division, or

a digital meter, which reads in increments of

1/10th of a percent. The flue temperature is

sensed by a thermocouple which is secured in the

flue gas sampling probe. This thermocouple

produces a millivoltage which is read on a meter

in degrees Fahrenheit. In the case of the analog

meter, a gross stack temperature reading is

displayed on a meter, 10 degrees per scale

division. The digital meters display net stack

temperature in one degree increments by sub-

tracting room temperature from the total reading.

A smoke test is performed by pushing a button

which in turn starts an electric pump that draws a

certain volume of flue gas through a piece of

filter paper, producing a smoke spot. This spot is

then compared to a chart with standard smoke

readings from zero to nine.

All models come in steel carrying cases to

prevent damage to the instruments while they are

being carded in cars or service trucks. The

models that are removed for testing are in foam

lined, steel carrying cases, while the other models

are built into steel carrying cases, and need no

removal for testing.

These instoaments do not require pumping, and

there are no fluids to change. However, some

models require 115 volt house current. Other

models are available with Ni-Cad rechargeable

batteries which can operate the instruments for

several hours between charges.

There is a distinct advantage in using the elec-

tronic analyzers, because most can measure 0 2 or

temperature continuously, and the effect of burner

adjustments can be quickly observed. This allows

you, after the draft has been set, to make a series

of burner adjustments, observe and record 0 2

and/or temperature. At the same time, you could

also be taking smoke readings so that a smoke vs.

O2 curve could be established to pinpoint the

optimum air setting for the burner.

Other Advanced Multi-Purpose

Test Instruments

The following are just two of the many sophisti-

cated, multi-purpose test instruments now

available to assist technicians with heating

system installation, adjustment, and maintenance.

FIGURE 52 Testo342 Combustion Analyzer

Testo 342 Combustion EfficiencyAnalyzer

(hand-held) measures 02, CO2, CO, NO, °F,inches

of'_:C., and efficiency. Backlit LCD screen enables

use in darkareas. The unit can also communicate

test results to an optional printervia wireless

infraredtransmission (similar to aTV remote

control) for instant printouts.

FIGURE51LynnModel6500combustion

efficiencyanalyzer

Bacharach CA 40H Combustion

Analyzer (hand-held) measures and

displays 0 2, CO, draft, air temperature,

and stack temperature while simulta-

neously computing and displaying com-

bustion efficiency, net stack temperature,

CO 2, excess air, and CO referenced to 3%

0 2. An advanced version stores up to 100

tests in merr_gry and downloads to a

computer through a built-in RS 232 port.

RGURE 53 Bacharach CA40H CombustionAnalyzer

Measurement of

Flue Gas Temperature

Flue gas temperature (often called stack tempera-

ture) is normally determined with a bi-metallic

dial thermometer with a range of 200°F to

1000°E (See Figure 54.) The bi-metallic element

is a single helix, low mass coil fitted closely to

the inside of astainless steel stem. The stainless

stem is 3/16 inches OD and can be easily inserted

into a 1/4 inch hole in a flue pipe. The sampling

hole should be at least two flue diameters above

the breeching or elbow, at the breeching but

ahead of the barometric damper. (See Figure 60.)

Stem mounting sleeves are also available, which

make it possible to hold the thermometer in pipe

ducts with the stem inserted at the proper length.

RGURE54Fluegasthermometers

The thermometer should be inserted to the

approximate mid-point of the stack.

On these types of thermometers, the dial can

easily loosen from the stem and rotate so that

inaccurate temperature readings are displayed.

There have been cases where dial thermometers

have been as much as 200°F off from the actual

temperature, It is recommended that these

thermometers be calibrated from time to time

against a mercury thermometer by inserting both

side-by-side in a heated flue or duct.

The net stack temperature is found by determin-

ing the room temperature and subtracting this

value from the flue gas temperature. Don't forget

to do this! Also, it is extremely important that

flue gas temperature is measured at steady-state

condition. This usually requires about fifteen

minutes of burner operation. However, the best

way to determine if the system is at steady-state

is to insert the thermometer in the flue pipe.

When the temperature rises less than 5°F during a

one minute period, steady-state conditions exist.

Remember, if you don't wait for steady-state you

will record a temperature that is lower than

actual, and this will produce a steady-state

efficiency which is higher than actual. By doing

this, you may think the unit is operating at a

reasonable efficiency level when it really isn't.

You may also be denying your oil company the

opportunity to recommend the installation of a

new, flame retention oil burner that can aid in

achieving high steady-state efficiency, and

represent a savings in fuel cost to the homeowner.

There are other devices that cart be used to

measure the flue gas temperature such as

mercury-filled glass thermometers or

thermocouples with potentiometers. Don't even

consider a glass thermometer for other than

calibration use, and even then it's risky! They are

fragile and easily broken and, furthermore,

mercury vapor is hazardous. Thermocouples,

however, are a possible alternative to dial

thermometers; they are accurate, have a quick

response to temperature change, and are easy to

use. Although thermocouples are inexpensive, a

good potentiometer is considerably more

expensive than a dial thermometer.

Smoke Measurement

You should realize by now that determining only

the steady-state efficiency does not present the

whole picture needed to properly adjust an oil

burner. High efficiency with a high smoke level

will likely become low efficiency or, even worse,

require a service call resulting from plugged flue

passages. The objective of a smoke test is to

measure the smoke content in the flue gases and

then, in conjunction with other steady-state test

results, adjust the burner to optimum operation.

The American Society for Testing and Materials

in 1965 adopted a standard method of test for

FIGURE 55 Bacharachsmoke spot tester

smoke density in flue gases from distillate fuels

(ASTM D2156). This method covers the

evaluation of smoke density in the flue gases

from burning distillate fuels, it is intended

primarily for use with home heating equipment

burning kerosine or heating oils.

A test smoke spot is obtained by pulling 2250

cubic inches of flue gas through a square inch of

standard filter paper (or a proportionally smaller

volume of flue gas and proportionally smaller

filter area). The color (or shade) of the spot thus

produced is visually matched with a standard

scale, and the smoke density is expressed as a

"smoke spot" number.

The most widely used smoke measuring device is

based on the principle of filtering soot particles

out of a sample of flue gas. The device is quite

simple and nagged. (See Figure 55.) It consists of

a hand held piston in a tube with a clamping

device at the inlet to the tube to hold a piece of

white filter paper. The inlet tube is connected

through flexible rubber hosing to a solid steel

probe that can be inserted into a 1/4 inch hole in a

flue pipe or duct. At the outlet end of the piston is

a handle that is used to stroke the piston within

the tube. The smoke sample should be taken at

the same stack location as the CO 2, 0 2, and

temperature readings.

FIGURE 56 Oil burnersmokescale

The operation of the device is simple and

consumes very little time. After fineburner has

been in operation for at least five minutes, place

the filter paper into the clamping device, insert

the steel probe into the flue pipe hole, and slowly

withdraw the piston fully from the tube, Hold the

piston in the fully open position for about 3

seconds and then slowly push the piston corn-

pletely in. Repeat the stroking procedure ten

times. This allows an exact volume of gas to be

passed through the filter paper. When the filter

paper is removed, the amount of soot which has

been filtered onto the paper will leave a circular

colored spot. The darkness of the "smoke spot" is

then compared against a Bacharach Oil Bumer

Smoke Scale (a scale from 0 to 9 representing

increasing shades of darkness). If there is no soot,

the paper will be white colored.

Figure 56 shows the rating scale used by

Bacharach. Actual comparison to determine a

number rating is made by holding the filter paper

behind the smoke scale so that the spot on the

filter paper fills the center hole in the spot on the

smoke scale. This allows direct comparison with

the various spots on the scale.

The Lynn Combustion Analyzers also measure

smoke by using a diaphragm pump to draw a

measured volume of flue gas (2250 cu. in. per sq,

in. of filtering area) through filter paper (identical

to the paper used in the Bacharach True-Spot

Tester) that is inserted in the gun assembly. The

"smoke spot" is then compared against an oil

bumer smoke scale.

Draft

Correct draft is essential for efficient burner

operation. There are two types of devices that are

commonly used to measure draft--a Bacharach

Draftrite Pocket Draft Gauge or a Bacharach

MZF Draft Gauge. The Draftrite is small and

easy to use, while the MZF is more sensitive yet

FIGURE 57 Draft measurement devices

also easy to use. The Draftrite is a slim, hand

held, rectangular device with a curved draft scale

placed behind a free floating pointer. The back of

the device has an opening in which short metal

tubes screwed in series can be inserted. The end

of the metal tubes can be placed in the flue pipe,

and the pointer will indicate the draft on the

numbered scale. These metal tubes may melt if

left in the flue for too long. Be careful!

The MZF Draft Gauge also contains a pointer

located over a large scale. Rubber tubing is

connected to an opening at the rear of the device

and also is fitted, at the other end, onto a metal

probe. Upon inserting the probe into a flue or

over the fire in a boiler or furnace, the pointer

moves in direct proportion to the magnitude of

the draft.

Either of these devices are acceptable for use in

determining draft, if they are used properly. Both

draft measurement devices are shown in

Figure 57.

Carbon Monoxide (CO) Testing

There is little chance of dangerous levels of

carbon monoxide being produced by a properly

installed, properly adjusted, well-maintained oil

heat system which is supplied with adequate

combustion air. However, the oilheat technician

should always test for the gas as part of every

service/maintenance call. This can be done

quickly and easily with a wide variety of elec-

tronic test instruments now available. CO test

capability is included in many multi-purpose

instruments, and separate CO testers are also

available. See Figure 59 for CO level standards.

The Lynn Model 7400 Carbon Monoxide

Analyzer isa hand-held,batterypowered CO

testerthat fitsinto hard-to-reachareas and

features a cleardigitaldisplayreading.

FIGURE 58

FIGURE59COlevelstandards

CO Level Standards

The following standards were in effect at the time this book was edited (1997):

ASHRAE American Society of Heating, Refrigerating and Air Conditioning Engineers -

Standard 62-89

ASHP_E states the ventilation air shall meet the outdoor air standard. See U.S. EPA

standards below.

EPA Environmental Protection Agency

EPA recommends 9 ppm or lower as an ambient air quality goal averaged over

eight hours.

EPA recommends 35 ppm or lower as an ambient air quality goal averaged over

one hour.

OSHA

ANSI Z21.1

Occupational Safety and HealthAdministration

The maximum allowable concentration (50 ppm) for aworker's continuous exposure

in any eight hour period.

American National Standards Institute

Maximum concentration (200 ppm) allowed from an unvented space heater, when

measured on an air-free basis.*

Maximum concentration (400 ppm) allowed in furnace flue gas, when sampled on an

air-free basis.*

Maximum concentration (800 ppm) allowed from an unvented gas oven, when

measured on an air-free basis.*

*Instruments can determine the amount of CO on an air-free basis by first measuring the amount of

0 2 and CO present in the sample, and then calculating by the equation below:

20.9 x CO = CO Air-Free

20.9-0 2

This compensates for the amount of excess air provided by the burner. Excess air from a burner

dilutes the products of combustion and causes a test for CO to be understated. A CO air-free

measurement eliminates the excess air dilution.

The above information was taken with permission from the pamph/et "Carbon Monoxide Safety," @1996, Bacharach, Inc.

RESIDENTIAL OIL

BURNER ADJUSTMENTS

Now that you have reviewed the basics of

combustion, combustion efficiency, and the

operation and use of measurement equipment,

you are prepared to study testing and adjustment

procedures. The first and most important proce-

dure is the proper adjustment of the burner,

whether it be for an annual tune-up, the installa-

tion of a new flame retention burner, or the

reduction of a firing rate. Each of these proce-

dures ultimately requires that the burner be

adjusted properly for optimum fuel utilization. A

newly installed flame retention burner adjusted to

produce a No. 2 smoke or a 9 percent CO 2, when

lower smoke and higher CO2 levels are possible,

will not provide the homeowner with the full

benefits of this new unit.

This chapter describes in a step-by-step manner

good industry practice for the proper adjustment

of residential oil burners.

Be sure that on any heating installation there is

adequate fresh air available to support combus-

tion. Appliances located in confined spaces

should have two permanent openings, one near

the top of the enclosure and one near the bottom.

Each opening should have a free area of not less

than one square inch per 1000 Btu per hour input.

Or, provide outside combustion air. See NFPA 31

for complete application details.

Facts About High CO 2 Levels

Modem flame retention burners permit adjust-

ment to high or low CO 2 levels. For example, in

ce_n packaged applications, 14% CO 2 at a

trace of smoke level is not uncommon. On the

surface, this appears to be excellent because the

system efficiency can be in the 85+% range.

However, there are some very important consid-

erations:

1. Some boilers and furnaces have very generous

combustion areas and flue passages. Non-

flame retention burners operating at a nominal

8% CO 2 and No. 1 smoke could typically

make it through a heating season without

sooting the more generous, very forgiving

units. AFUE rating was not the primary

concern in the old days.

2. Many of today's appliances are more com-

pact, with reduced combustion areas and

tighter flue passages.

3. Burner adjustments have become more

important, and adverse conditions such as

sooted heat exchangers and even deterioration

of refractories can occur if sound principles

are ignored.

4. When flue passages are more restricted, the

CO 2 vs. smoke level must be set to accommo-

date this.

Hodzor_l Flue Con_on

flue pipe

Draft regulator ,,_,_

Location for

sampling hole, 1/4"diam. "-,

[]

Furnace or

boiler

Chimney

........... -r

Oil burner

...l....p..

..-t....p...

Vertical Rue Connection

Location for

sampling hole

breeching._! 60

| .

FIGURE 60 Desirable location for 114=flue pipesampling hole fortypical chimneyconnections

A. Locate hole at least one flue pipe diameter on the furnace or boiler side of the draft control.

B. ideally, hole should be at least 2 flue pipe diameters from breeching or elbow.

5. Refractor.,, material is generally capable of a

maximum operating level rated at 2300°E

Wet-based boilers normally utilize a reduced

amount of refractory, which is usually

positioned so that it can transfer heat to the

surrounding water-backed surfaces. There is

little danger of overheating the refractory in

this application. Therefore, higher CO 2 levels

can be utilized with due consideration being

given to item 4 above. In dry-base boiler

models and furnaces, the refractories are

selected to withstand the elevated tempera-

tures of high performance burners. While each

application is different, we do know that the

highest flame temperature occurs at elevated

CO 2 levels. For example, a burner operating

at 13.5% CO 2 and zero smoke may be near

the 2100°-2200°F range and could possibly

exceed 2300°F at 14.5% CO 2 and a trace of

smoke. Sustained firing at this level could

seriously affect the integrity of the combustion

refractory.

Keep in mind that actual performance levels vary

among finebroad range of burner applications.

However, service "call backs" will be reduced

whenever these principles and guidelines are

understood and followed. Heating appliances

should be adjusted with suitable combustion test

instruments.

Combustion levels must be compatible with each

design application. It is always good practice to

consult the appliance manufacturer's installation

literature for the recommended performance

specifications.

Oil Burner Adjustment

1. PROCEDURE PREPARATION STEPS

A. Calibrate and Check Operation of

Measuring Equipment. Follow

manufacturer's recommended procedures for

calibration and equipment check out.

B. Prepare Heating Unit for Testing. Drill a I/4

inch hole in the flue between the appliance

and the barometric draft regulator, if not

already there, as shown in Figure 60. If space

permits, the holes should be located in a

straight section of the flue, at least two flue

Correlation of Percent of CO 2,

0 2 and Excess Air

Carbon Dioxide Oxygen Excess Air (approx.)

I5.4 0.0 0.0

15.0 0.6 3.0

14.5 1.2 6.0

14.0 2.0 10.0

13.5 2.6 15.0

13.0 3.3 20.0

12.5 4.0 25.0

12.0 4.6 30.0

11.5 5.3 35.0

11.0 6.0 40.0

10.5 6.7 45.0

10.0 7.4 50.0

The ranges thatyou willuse most frequently

are bold-faced.

FIGURE 61 Correlation of percent of CO2, 02, and

excess air

diameters from the elbow in the flue pipe and

at least one diameter from the draft regulator.

If one does not exist, another 1/4 inch hole

should be drilled in the fire door or inspection

cover to check over fire draft.

Clean and Seal HeatingAppliance. Make

sure the burner air tube, fan housing, and

blower wheel are clear of dirt and lint. Seal

any air leaks into the combustion chamber,

especially joints between sections of cast-iron

boilers (and around fire door).

Nozzle Inspection. Annual replacement of

nozzles is recommended. The nozzle size

should match the design load. DO NOT

OVERSIZE. Short cycles and low percent

"on" time result in higher overall emissions

and lower thermal efficiency. All systems must

have an oil filter installed in the oil supply line

to protect the oil handling components. Care

should be taken to prevent air leakage into the

oil suction line. Use continuous runs of copper

tubing and use a minimum number of joints

and fittings. Always use flare fittings.

Select the nozzle and spray pattern, using

burner manufacturer's instructions whenever

possible. On burner-boiler or burner-furnace

matched assemblies, use the appliance

manufacturer's instructions.

E. Adjustment of Electrodes. Adjust ignition

electrodes according to burner manufacturer's

instructions to assure prompt ignition.

F. Operate Burner. Operate burner, adjust air

setting for good flame by visual inspection,

and run for at least 10 minutes or until

operation has stabilized.

G. Check Pump Pressure. Bleed air from pump

and supply piping. Check pump pressure and

adjust to I00 psig, if necessary (or to

manufacturer's specification).

2. COMBUSTION ADJUSTMENT STEPS

H. Set Draft. Check the draft reading over the

fire with a draft gauge through a1/4" hole

drilled in the fire door or inspection door.

(This hole should be in the inspection door for

oil-fired matched units, and in the fire door

for conversion installations. If possible, the

hole should be above the flame level.) Adjust

the barometric draft regulator on the flue to

obtain the overfire draft recommended by the

manufacturer. If no such recommendations are

available, set overfire draft to assure a

negative pressure within the combustion

chamber (usually -.02 inches W.C.).

With some equipment, it will not be possible

to take draft readings over the fire. In this

case, adjust the draft regulator to give a

breech draft reading between -.04 and -.06

inches W:C., taken at the sampling hole.

Seal draft or sampling hole in inspection or

fire door after these tests have been made,

using a plug, bolt, or high temperature sealant.

Some appliances are designed for positive

pressure firing. Follow the manufacturer's

recommended performance specifications for

draft levels and venting requirements.

I. Check Smoke Readings. After burner has

teen operating 5 or 10 minutes, take a smoke

measurement in the flue, following the smoke

tester instructions. Oily or yellow smoke spots

on the filter paper are usually a sign of

unburned fuel, indicating very poor combus-

tion, which could possibly produce high

emissions of carbon monoxide and unburned

hydrocarbons. When retrofitting in older

appliances, this condition can sometimes be

caused by too much air, or by other factors, if

this condition cannot be corrected, major

renovation or even equipment replacement

may be necessary.

Adjust Air Setting.

(1) Set the burner air controls to obtain a

trace of smoke at steady state operation.

Remember, as the excess air is reduced,

the percent of 0 2 decreases and the

percent of CO 2 increases. By increasing

the excess air, we lower the CO 2 percent

and raise the 0 2 percent. The relationship

between CO 2, 0 2, and excess air is shown

in Figure 61. The levels most frequently

encountered in oil burner servicing are in

bold face.

(2) At the trace level, measure the CO 2 or 0 2.

This is typically around 13% CO 2 /3.3%

02 . (See Figure 62.) Now, increase the

air setting until the CO 2 is reduced by 1 to

2 percentage points from a trace of smoke,

or the 0 2 is increased by about 2 to 3

percentage points.

(3) Make a smoke test. It should be zero. You

have built in a margin to accommodate

v_ables that could be encountered during

the heating season.

(4) Lock the air adjustment and repeat draft,

CO2/O 2, and smoke measurements to

make sure the setting has not shifted.

16 f 1

Typioa,

I_ Adjustment[ I

RGURE 62 Typicalsmoke vs. CO 2 percent

RECORDING OF READINGS

Now that you've performed your adjustment,

record the readings on a form similar to that

shown in Figure 63. This will be left to inform

the homeowner of the measurements you made.

This type of information is important for

homeowners to receive. It improves your image

and indicates to the homeowner that you and

your company are responsible and thorough.

Remember, horneowners are being told that

measurements are an essential part of proper

burner/furnace/boiler adjustment. Fill the form

out and leave it with the homeowner! If the test

results indicate poor or fair efficiency, recom-

mend to the homeowner that he or she contact

your oil company representative for a complete

evaluation and/or an energy conservation

recommendation.

THE ANNUAL CLEAN-UP

We strongly recommend that the following

procedures be performed each year in advance of

the heating season:

A. Fire Test the Unit

Does it function normally? Ask the

homeowner questions and listen to the

answers. If there are troubles with the unit,

you may need to make repairs or run a

combustion test.

B. Clean the Flue

Turn off the power. Put on a respirator mask

and leave the vacuum running with the

snorkel inside the area being cleaned to catch

airborne particles. Remove the flue pipe and

clean it thoroughly. Check the chimney for

blockage. Check the barometric regulator.

C. Clean the Secondary Heat Exchanger

Remove the flue collector box. Remove

baffles and scrub passages with a flue brush.

Shoot for "day one" condition to boost

efficiency. Look for cracks, etc. Use any

auxiliary clean-out ports.

D. Clean the Combustion Area

Older units may have a view or fire door for

access to the combustion area. You may have

to remove the burner and front plate to reach

the primary heating surfaces. Note the

refractory condition and repair or replace as

necessary. Be careful not to damage the

refractory material when cleaning ceramic

fiber chambers. Use a soot snorkel or make

one from 3/4" air conditioning or garden hose

with duct tape wrapping for a bushing.

Replace, Seal and Fasten

Put everything back in place, sealing leaks or

cracks with furnace cement and using sheet

metal screws on stack joints.

Furnace or Boiler?

Furnace: Open the blower compartment to

check filters, oil the motor and blower shaft

beatings, check V-belt tension and pulley

alignment. Brush lint and dirt from blower

wheel. Check blower mountings for noisy

operation.

Boiler: Oil circulator motor and bearing

assembly. Check circulator coupling. Drain

expansion tank if needed. 47

G. Service the Burner

Make sure the power is off.

Remove the pump strainer cover and clean

strainer. Replace cover gasket. Secure

cover.

3. Replace oil filter element, leaving the

canister clean and tight. Sludge or water

means the _'ak needs to be checked for the

cause. Assure oil lines are clean, straight

and all fittings are leak-free. Use flare

fittings; never compression fittings.

4. Remove the firing assembly. Clean internal

tubing. Check electrode porcelains for

cracks. Replace nozzle with specified type.

Do not over-tighten. Set electrodes to

manufacturer's specs.

5. Clean any dirt from combustion head slots

and holes. Inspect for damage and suitable

firing range. Replace firing assembly.

6. If the burner has not been removed, check

the condition of the combustion head using

a flame mirror and flashlight. It should be

recessed 1/4" from the inside chamber

wall, but check manufacturer's specs to be

sure. Also check nozzle concentricity.

7. Clean transformer bushings and springs as

well as the cad cell surface. Check bracket

alignment for good flame sighting.

8. Use a small brush and vacuum cleaner

snorkel to clean the air inlets and blower

vanes to "like new" condition.

9_ Oil the burner motor with 3-4 drops of

SAE 20 or 30 oil. Some motors are

permanently lubricated, and should not be

oiled.

10. Check to see that all wiring connections

are secure and insulation is not broken or

cut.

11. Time the safety lock-out while you bleed

all air from the pump. Test pump pressure

and set at 100 psig or to manufacturer's

specs. Check the cut-off to see that

pressure drops to approximately 80% of

operating level.

12. Restore power. Turn finebumer ON. "view

the flame for uniformity and concentricity

with no impingement.

H. CombustionTesting

1. Refer back to combustion adjustment steps

on page 46.

2. Take a gross stack temperature reading.

Subtract room ambient temperature and

use an efficiency chart to determine

steady-state readings with the net stack

temperature and CO 2 or 0 2 levels.

3. Cycle the burner to assure prompt ignition

and smooth operation. Repeat cycling,

purging air bubbles from nozzle adapter

until cut-off is clean with no after-squirt.

I. Check Safety andAuxiliary Controls

Cut power to the blower or circulator motor

and cycle the burner until safety limits shut

the burner off. Check automatic feed valves,

low water cut-off and pressure relief valves.

Flush low water cut-off valves. Use sight

glass on steam units to check water level.

Determine that limit controls will shut down

the burner if operating controls fail. Be sure

the installation meets current codes. Cycle the

burner and observe one complete operation

sequence.

J. Clean theArea

K. Reset Thermostat and Operating or Limit

Control Temperature Settings

L. Record your Findings

Make a written record of anything unusual or

needing service. Give a copy to the customer and

your service manager. Arrange for follow-up.

FIGURE 63 Testreportform

The following test results are based upon measurements

of your heating system performed on date

Efficiency (%)

Smoke

CO2 (%)

0 2 (%)

Gross Stack Temperature (°F)

Room Temperature (°F)

Net Stack

Temperature (°F)

Overfire Draft Inches W.C,

Stack/Breech Draft Inches W.C.

Notes:

Technician

XYZ OIL COMPANY

555-6666

BASIC TROUBLESHOOTING

Recommended Equipment

1. Electrical test meter (VOLTS, OHMS,AMPS).

2. Ignition transformer tester,

3. Combustion analyzerkit (oxygen orcarbon

dioxide, smoke, stack temperature, draft, system

efficiency).

4. Pressure/vacuum gauge (0-200 psig and

0-30: Hg).

5. Full assortment of standard hand tools.

Preliminary Steps

1. Check oil level in supply tank.

2. Make sure all oil line valves are open.

3. Examine combustion chamber for excessive

unburned oil. Clean if necessary.

4. Measure line voltage at primary control input

connections. It should be 120 volts. I_wer than

105 voltsAC may cause operating problems. If

there isno reading, check for open switches or

circuit breakers.

5. Make sure _ermostat or other controlling device

is calling for burner operation.

6. Check primary' control to see if safety reset switch

is "locked out."

Determining Malfunction Causes

I. Disconnect nozzle line connector tube and

reposition it so that it will deliver oil into a

container. Tighten flare nut at pump discharge

fitting.

2. Reset primary control safety switch if it is locked

out. Turn power ON. Observe the following:

• Contact action of primary relay control.

Does it pull in promptly, without arcing

erratically or chattering?

• Oil delivery. You should have an immediate,

clear, steady stream, "Whitefrothy oil means air

in the supply system, which must be corrected.

No delivery means severe restriction some-

where.

. Ignition arc. You should hear ignition arc

buzzing. If not, test output voltage of trans-

former. If below 9,000 volts, replace.

° Motor. Does it pull upquickly and smoothly?

Listen for RPM change and audible "click" as

the centrifugal switch disconnects start

(auxiliary) winding.

If cause of failurehas not been identified:

•Reconnect nozzle tine fittings for burner fire

test.

.Reset primary contro! if necessary. Run several

cycles. Observe flame quality. Use a flame

mirror, if possible, to see if flame base is stable

and close tocombustion head. Is flame

centered, uniform in shape, and relatively

quiet?Are head and chamber free of carbon

formations or impingement? Sometimes a

defective or partially plugged nozzle can cause

trouble.

Additional P_edures:

If the problem still has not been identified, a more

thorough evaluation of the basic system must be

made. The following procedures may be helpful:

Primary Control System (Cad Cell Type) starts

burner, supervisesoperating cycles, shuts burner off

at end of heat call, and locks out ON SAFETY if

thereis a flame failure.

1. Measure electrical voltage at primary input

(usually black) andneutral lead (usually white)

connections. It should be 120 volts.

2. Jumper thermostat (TT terminals)or other,vise

energize primary control.

3, Control relay should pull in. If not, make sure

wiring connections are secure and cad cell isnot

"seeing" stray light (chamber glow).

4. If relay pulls in, but motor fails to start, measure

voltage between neutral lead (usually white) and

primary control lead for motor (usually orange).

Relay switch contacts may be defective, causing a

severe voltage drop.

5. Ifrelay fails to pull in, or is erratic and chatters,

even when wiring connections are secure, replace

control.

6. Check safety lockout timingby removing one F

(cad cell) lead from control. Start burner and

count seconds until control le.2ksout.Time

should be reasonably close torating plate

specifications on control body.

7. Tocheck cad cell, start burner and unhook both

cad cell leads from control FF terminals. Jumper

FF screw terminals to keep burner operating.

Measure OHMS resistance across cad cell leads

as it views the flame. It should be 1600 OHMS

or less. Preferred reading is 300-1000 OHMS.

Next, with meter connected to cad cell leads, turn

burner OFF. DARK conditions should give a

reading of 100,0rXlOHMS or infinity. If reading

is lower, let refractory cool down, and check for

stray light entering burner through air inlet, or

around transformer base-plate. If cad cell is not

performing within these guidelines, replace it.

8. The control may l>egoverned by a room thermo-

stat. Be sure heat anticipator setting or rating of

the thermostat matches the 24 volt current draw.

This information is usually printed on the control

body Erratic operation may be caused by

improper anticipator settings. Settings are

typically .2or .4 amps. This value can usually be

measured by connecting amultitester in SERIES

with one of the Tr leads, and reading the value on

the appropriate milliampere scale.

The Ignition System is generally comprised of an

ignition transformer and two electrodes that deliver a

concentrated spark across a fixed gap to ignite oil

droplets in the nozzle spray.Delays in establishing

spark at the beginning of the burner cycle can result

in "puff backs," which can fill the room with fumes.

If spark is inadequate, burner may lock out on safety.

If transformer is suspect, make the following checks:

I. Measure voltage between transformer/primar¢

lead and neutral connection. It should be 120

volts on the primary input side.

2. Second_ terminals of a good transformer

deliver 5000 volts each to ground, for a total of

10,0rX)volts between theterminals. Measure this

with a transformer testeror use a well-insulated

screwdriver to draw an arc across the two springs.

This should be at le_t 3/4" in length, Check each

secondary output terminalby drawing astrong arc

between the spring and base. If arc is erratic,

weak, or unbalanced between the two terminals,

replace transformer.

3. Transformer failures and ignition problems can be

caused by the following:

•An excessive gap setting on ignition electrodes

will cause higher than normal stress on the

internal insulation system.This can lead to

premature failure. Set electrode gap according

to manufacturer's instructions (typically 5/32").

•High ambient temperatures can lower effective-

ness of interna! insulation system.

•High humidity conditions can cause over-the-

surface arc tracking, both internally and

externally, on ceramic bushings.

•Carbon residue and other foreign materials

adhering to porcelain bushings can contribute

to arc trackingand subsequent failure.

,Low input line voltage can cause reduced

transformer life. It should be at least 105 volts

AC.

•Ignition electrodes must have good contact

with transformer springs. Any arcing here must

be eliminated.The only arcing should be at the

electrode tips.

•Electrode insulating porcel_ns must be clean

and free of carbon residue, moisture, crazing,

or pin hole leaks. Leakage paths can contribute

to faulty ignition.

•Electrode settings must conform to specifica-

tions for gap width, distance in front of nozzle

face, and distance above thenozzle center line.

Improper positioning can produce delayed

ignition, spray impingement on electrodes,

carbon bridging, and loss of ignition, which can

lead to safety lockouts.

• Replace electrodes if tips are worn or eroded,

Replace questionable porcelain insulators.

The Burner Motor drives the blower wheel and fuel

pump by means of a shaft coupling.To diagnose

motor problems, follow these guidelines:

1. Motor fails to start.

•Check for adequate voltage between motor/

primary lead and neutral connection with the

motor energized, Line voltage must be within

10% of motor rating plate specified voltage.

•If motor hums when energized, but shaft does

not rotate, the start switch may be defective.

With the power turned OFF, rotate blower

wheel by hand. If it turns freely, replace motor.

•If blower does not turnfreely, check for a

bound fuel unit, jammed blower, dry bearings,

or agrossly misaligned shaft coupling. Oil

bearings with SAE 20W oil. Or, if permanently

lubricated, does not need tobe oiled.

2. Other motor-related problems.

• If overload protection has tripped, start motor

and measure current draw. it should not exceed

rating plate specifications under load condi-

tions by more than 10%.Excessive amp draw

usually indicates an overload condition,

defective start switch, or shorted windings.

• If motor is noisy,check alignment of shaft with

coupling. Tighten or slightly loosen motor-to-

burner-housing bolts in an alternate sequence,

Check for l_se blower wheel, excessive radial

shaft play or loose start switch parts,

• It is difficult, and usually not cost effective, to

rebuild motors in the field. Replace them,

instead.

• If motor operates normally, but does not drive

pump shaft, check coupling for slippage due m

stripped end caps.

The Fuel Pump transfers oil from the supply tank,

cleans it with a strainer or similar mechanism,

pressurizes the oil for good atomization at the nozzle,

and provides a good shutoff at the end of the run

cycle. Manufacturers provide excellent installation

and set€ice information. Please read and follow it

carefully: Many burner problems can be traced to

incorrect installation of oil piping and fittings.

OPTIONS

This manual is intended to provide you with

information that can aid you in performing

energy conservation modifications on residential

oil-fired heating equipment. A sound understand-

ing of the fundamentals of combustion theory is

essential. Also, a full understanding of the

significance of instrument measurements and

their proper use is an integral part of analyzing all

energy conservation options. Therefore, the five

previous chapters offered background informa-

tion that will be needed to adequately perform the

recommended energy conservation modifications.

This chapter discusses the criteria and summa-

rizes the procedures associated with the recom-

mended energy conservation modifications. The

two modifications are:

•'Replacement of a poorly operating oil burner

with a properly fired flame retention type

burner.

V Replacement of a poorly operating heating

appliance with the properly sized, high

efficiency boiler/burner or furnace/burner

unit.

In order to install a correctly matched heating

unit with the proper firing rate for the dwelling,

a heat loss calculation must be performed. See

Figure 70 for outdoor winter design temperatures.

Flame Retention 0il Burners

Flame retention oil burners, introduced in the late

1960's, represented a major breakthrough in

technology, and can produce significant improve-

ments in overall oilheat equipment efficiency

while simultaneously reducing the number of

burner-related service calls. The term "flame

retention" indicates that the combustion head is

designed to impart considerable rotation into the

air stream. Pressure drop across the head is

greater than with non-retention heads. This

causes high velocity air to enter the combustion

chamber and holds the flame at, but not on, the

retention head. (See Figure 65.) Flame retention

combustion heads are designed in different sizes

to match a range of nozzle firing rates. (Figure 66

shows recommended firing rates for Beckett AF

and AFG burners. Figures 67 and 68 show

recommended firing rates and air tube!head

combinations for Beckett AF II burners.) Typi-

cally, flame retention burners use motors that

operate at 3450 rpm rather than 1725 rpm.

The effect of this air handling design is to create

better air-oil mixing and contain the flame within

the air pattern. This produces a higher flame

temperature with less excess air. From Chapter 1,

you know this means better heat transfer and

FIGURE64 Flameretentioncombustionheads

BECKETFMODELAFG Flame retention, high speed,

.40to 3.0 gph, broad firing range

Non-Flame Retention Combustion Flame Retention Combustion

Nozzle

Combustion Air

Target Wall

r Vanes

CombustionChamber Non-Flame Retention

Combustion Head

Rear V_ew

Cast Iron

Nozzle

Rame Retention

_\ Combustion Chamber Combustion Head

(Optional) Rear View

Stainless Steel

Circumferential

Slots

Radial Vanes

FIGURE 65 Non-flame retentionand flame retention combustion

higher overall efficiency. More useable energy is

produced from the same amount of oil consumed.

There are other advantages to flame retention.

There is less effect on the flame from stack draft

v_ations, and pulsation is almost never a

problem. There are fewer products of incomplete

combustion to reduce burner efficiency and lead

to maintenance. Another advantage is that during

off-cycles the retention head reduces the flow of

air through the burner, over the heat exchanger

and out the stack. Therefore, less heated air is

removed from the residence.

The Beckett AF II oil burner eliminates the need

to stock numerous burner models to accommo-

date different types of applications. The AF II

meets all the requirements of wet base and wet

leg boilers, furnaces, dry base boilers, and water

heaters. All that changes is the air tube/head

combination you use. The AF II 150 provides

capacities of .75 to 1,50 gph, 105,000 to 210,000

Btu,qar.For applications requiring lower firing

rates, the AF II 85 can be used. See Figure 67.

Criteria for Installing

Flame Retention Oil Burners

The decision whether to replace an old, low-

speed burner with a high speed, flame retention

unit is not difficult by any means. In general,

most burners of older design should be replaced.

However, there are some older units that still

operate at high efficiency. Remember--

recommending that a flame retention burner be

installed does not mean that a customer will

actually purchase the new burner. Nevertheless,

the objective is to save energy and reduce fuel

costs for homeowners, and flame retention

burners can do this.

The following criteria should be used as a guide

RECOMMENDED FIRING RATES gph

H_D ATC STATIC FRONT With Inlet Air Shut.Off Without inlet A|r Shut.Off

DESIGN CODE HEAD PLATE VENTURI MIN MAX MIN MAX

Fixed XR F0 3-3/8" None 0,40 0.75 0A0 0.75

Fixed XN F3 2-3/4" None 0.75 1,25 0,75 1.25

Fixed YB F6 2-314" None 1.25 1,65 t,25 1.65

Fixed XO F12 2-3/4" None 1.65 175 !,65 2,00

Fixed XP F22 2-3/4" None 1.75 2.25 1_75 2.50

Fixed XS F31 None None 2.50 2,75 2.50 3.00

Fixed "MA L1 3-3/8" 4 holes 0,40 0.75 0A0 0,75

Fixed MB L1 3-3/8" 8 holes 0,50 1,00 0.50 1.00

Fixed * MC L1 2.3/4" 8holes 0_50 1.25 0.50 1,25

Adjustable MD Vl 2-3/4" 8holes 0,75 2,00 0.75 2,75

Adjustable *ME Vl 2-3t4 _ 0 holes 1.00 2.00 1.00 2.75

NOTE: *Used on OEM applications Only.

FIGURE 66 Recommended firing rates for BeckettAF andAFG burners [

I53

54 i

AFII AIR TUBE COMBINATION AND FIRING RATE CHART

FIRING RATE RANGE

AFII 85 I AFII 150

Head Design -Adjustable w/stop screw -typical applications, wet base boilers

H_50 HUX70 HLX90 HB AF2-6 .4-.85 GPH ,75-1.35 GPH

HLX30" H_50 ' HLx70" Hffxg0 _HC AF2-9 N/A ,75-1.50 GPH

HLX30 L HLX50 HLX70 H_90 ......HD AF2-6 .4-,85 GPH .75-1.10 GPH

HLX30 HLX50 H_70 HLX90 HE AF2-9 t_A .75-1.35 GPH

Head Desl n - Fixed- typical applications, furnaces, dry base boilers and water heaters

FBX50 FBX70 FBX90 HF FB0 .4-,65 GPH .75-1.00 GPH

FBX30 FBX70 FBX90 HG FB3 .55-.85 GPH .85-1.20 GPH

' FBX30 i FBX50 ' FBX70 ' FBX90 RH N/A 1.10"1,25 GPH

HI N/A 1.15-1.35 GPH

RGURE 67 Beckett AF II air tub_ead combinationsand firing rates

in recommending replacement of older oil

burners. You should be familiar with these even

though you may not be responsible for recom-

mending replacement burners.

1. If, after burner adjustment, the steady-state

efficiency is below 75 percent, the burner

should be replaced with a flame retention

burner.

,If, after burner adjustment, the steady-state

efficiency is greater than 75 percent but the

smoke level is greater than 2, the burner

should be replaced with a flame retention

burner.

The firing rate for the replacement burner

should be determined by calculating the heat loss,

but it should not be less that 75 to 80% of the

manufacturer's rating for the particular boiler or

furnace. Also, installing a new burner with a

reduced firing rate often requires a new, smaller

combustion chamber. Always remember to

consider a new chamber or chamber liner when

installing a new flame retention burner. If the

appliance is equipped with a stainless steel

combustion chamber, the use of a chamber liner

is a must because the higher temperature levels

produced by flame retention burne_ can exceed

the temperature ratings of stainless steel cham-

bers and cause them to burn out.

It may have occurred to you that, based on our

criteria, almost all older oil burners should be

replaced! That is exactly the intent. When you

replace older, inefficient burners, your job

becomes easier, homeowners enjoy reduced fuel

consumption, and your company gains profitable

BECK_ MODELAFI185/150withFBXairtube

combinationfor drybaseboilers,fumaces,andwater

heaters

HS/HO

6 SLOTS

3=5/32" !,0 HB

2-15/16" _0 HO

HC/HE

9 SLOTS

3-5/32 _ I.o, HC

2/HE

RGURE 68 HLX air tube/head combinations for wet

base and wet leg boilers

sales business. Unforpanately, not all homeowners

will take your advice, and some homeowners

presently can't afford the cost of a new burner,

Also, it is much more cost effective to replace

a burner operating at 55 percent efficiency than a

burner operating at 73 percent.

FBO

AF II 85:.40_.65 gph

AF 11150:,75-1,00gph

FB3

AF II 85:,55-.85 gph

AF II 150: ,85-1,20gph

FB4

AF ii 150:1A0-1.25gph

FB6

AF II 150:1A5-1,35 gph

FIGURE69 Flameretentionheadsforfurnaces,

drybaseboilers,andwaterheaters

Installation of Matched Boiler/

Burner or Furnace/Burner

The installation of a new heating appliance

can involve the replacement of a steam

system with a forced hot water system, or the

replacement of an existing type of heating

system with a similar, but more efficient unit.

Often new controls and other auxiliary

equipment are required in conjunction with

the new boiler/burner or furnace/burner

combination. We recommend that all coal

converted boilers be replaced. These older

boilers were not designed specifically for

oilheat, so even a new flame retention burner

can only offer limited improvement. Also, the

wide open heat exchanger passages in coal

converted units, even if baffled, will never

achieve the heat transfer capability of modern

boilers. Attempting to modernize an old boiler

or furnace by installing new controls or

components is similar to modernizing an old

burner--they are both patch work jobs which

provide only partial relief without solving the

real problem.

The sizing of boilers or furnaces and the

installation of a properly sized unit are

beyond the scope of this manual. Even so, you

should realize that the greatest cost savings to

homeowners who own outdated, inefficiently

operated heating systems is to replace the

equipment with a new heating appliance.

Make burner adjustments for optimum firing

conditions following the procedure discussed

in Chapter 5.

Most likeb; your company has developed the

techniques and marketing ability to inform

homeowners of the long-term advantages and

cost savings associated with new equipment.

RGURE 70 Outdoor winterdesign temperatures

Outdoor Winter Design Temperatures

(°F /Dry-Bulb)* Source: 1993 ASHRAE Handbook -Fundamentals

State City 99% 97.5% State City

ALASKA

AnchorageAP -23 -18

FairbanksAP -51 -47

JuneauAP -4 1

NomeAP -31 -27

CONNECTICUT

BridgeportAP 6

Hartford,BrainardField 3

NewHavenAP 3

NewLondon 5

Norwalk 6

Norwich 3

Waterbury -4

DELAWARE

DoverAFB 11 15

WilmingtonAP 10 14

DISTRICTOF COL.

AndrewsAFB 10

Wash.NatLAP 14

IDAHO

BoiseAP 3 10

PocatelloAP -8 -1

INDIANA

Evansvi!leAP 4

FortWayneAP -4

IndianapolisAP -2

Lafayette -3

Muncie -3

SouthBendAP -3

TerreHauteAP -2

MAINE

AugustaAP -7 -3

Bangor,DowAFB -11 -6

Portland -6 -1

MARYLAND

BaltimoreAP 10 13

BaltimoreCo 14 17

FrederickAP 8 12

Hagerstown 8 12

Salisbury 12 16

MASSACHUSETTS

BostonAP 6

Framingham 3

NewBedford 5

Springfield,WestoverAFB -5

WorcesterAP 0

MICHIGAN

BattleCreekAP

Detroit

RintAP

GrandRapidsAP

Kalamazoo

LansingAP

SaginawAP

SaultSte.MarieAP

MINNESOTA

DuluthAP

InternationalFallsAP

Minneapolis/St.PaulAP

RochesterAP

St.CloudAP

NEWHAMPSHIRE

ConcordAP

Manchester,GrenierAFB•

Portsmouth,PeaseAFB

NEWJERSEY

AtlanticCity Co

NewarkAP

TrentonCo

NEWYORK

AlbanyAP

AlbanyCo

BinghamtonAP

BuffaloAP

ElmiraAP

Ithica

Newburgh,StewartAFB

NYCCentralPark

NYCKennedyAP

NYCLaGuardiaAP

NiagaraFallsAP

Poughkeepsie

RochesterAP

Schenectady

SuffolkCountyAFB

SyracuseAP

Utica

Watertown

NORTHCAROLINA

AshevilleAP

CharlotteAP

Fayetteville,PopeAFB

GreensboroAP

Greenville

Raleigh/DurhamAP

WilmingtonAP

Winston-SalemAP

-4

-3

-12

-21

-29

-16

-17

-15

-8

-6

-4

-2

-4

-5

-1

-4

-3

-12

-11

97.5%

-8

-16

-25

-12

-11

-3

-1

-6

10 14

18 22

17 20

14 18

18 21

16 20

23 26

16 20

56 (continued on next page)

FIGURE 70 Outdoor winterdesign temperatures

Outdoor Winter Design Temperatures (Continued)

(°F /Dry-Bulb)* Source: 1993 ASHRAE Handbook -Fundamentals

State City 99°/o 97.5% State City

OHIO SOUTHCAROLINA

AkrordCantonAP 1 6 Anderson

CincinnatiCo 1 6 CharlestonAFB

ClevelandAP 15CharlestonCo

ColumbusAP 0 5 ColumbiaAP

DaytonAP -1 4 FlorenceAP

Uma -1 4 GreenvilleAP

ToledoAP -3 I SpartanburgAP

YoungstownAP -I 4

VERMONT

OREGON BurlingtonAP

EugeneAP 17 22

MedfordAP 19 23 VIRGINIA

PortlandAP 17 23 Charlottesville

PortlandCo 18 24 Harrisonburg

SalemAP 18 23 NorfolkAP

RichmondAP

PENNSYLVANIA RoanokeAP

AllentownAP 4 9

AltoonaCo 0 5

ErieAP 4 9

HarrisburgAP 7 11

Johnstown -3 2

Lancaster 4 8

PhiladelphiaAP 10 14

PittsburghAP 1 5

PittsburghCo 3 7

ReadingCo 9 13

Scrantor,JWilkes-Barre 1 5

StateCollege 3 7

WiliiamsportAP 2 7

York 8 12

RHODEISLAND

Newport

ProvidenceAP

99%

-12

97.5%

-7

14 18

12 16

2O 22

14 17

12 16

WASHINGTON

Seattle,BoeingField 21 26

SeattleCo 22 27

Seattle-TacomaAP 21 26

SpokaneAP -6 2

WallaWallaAP 0 7

YakimaAP -2 5

WISCONSIN

Appleton -14 -9

EauClaireAP -15 -11

GreenBayAP -13 -9

LaCrosseAP -13 -9

MadisonAP -11 .7

MilwaukeeAP -8 -4

Racine -6 -2

WausauAP -16 -t2

AP= Airport AFB= MilitaryAirBase

Co= Office locationswithinan urbanareathatare affectedby thesurroundingarea.

Courtesyof theAmericanSocietyof Heating,RefrigeratingandAir-ConditioningEngineers,Inc.,

andBrookhavenNationalLaboratory.

* Designtemperaturesare basedon theassumptionthat the frequencylevelof a specifictemperatureover asuitabletimeperiodwill repeatin

the future.The selectedwinterfrequenciesof 99%and 97.5% enablethe engineertomatch therisklevel desiredfor the problemat hand.At

manylocations,meteorologicalevidenceindicatesthat thetemperaturesat the 99% levelmayvary in theorderof 2 to 4°F inany 15-year

periodfrom the previous15-yearperiod,andeven moreinany singleyearfrom the previousone. The proximityof the 99% levelto the median

of the annual extrememinimumtemperaturesindicatesthatextremelylow temperaturesoccurin rareextendedepisedesratherthanin long-

term summations(EcedyneCoolingProducts1980,Snelling 1985,Crow 1963).

NOZZLE MANUFACTURERS AND SPRAY PATTERNS

DANFOSS

AS-SOLID

AH-HOLLOW

AB-SEMI-SOLID

STEINEN

S-SOLID

DELAVAN

A-HOLLOW

B-SOLID

W-ALL PURPOSE

SS-SEMI-SOUD

HAGO

ES-SOLID

P-SOLID

SS-SEMI-SOLID

H-HOLLOW

MONARCH

R-SOLID

NS-HOLLOW

AR-SPECIALSOLID

PLP-SEMI-SOLID

PL-HOLLOW

SS-SEMI-SOLID

H-HOLLOW

NOZZLE CAPACITIES

U.S. Gallons per Hour No. 2 Fuel Oil

Operating Pressure: pounds per square inch

rate gph

@100 ................

psi 140 150 175

.40 .45 A7 ,49 .53

.50 .56 .59 .61 .66

.60 .67 ,71 ,74 .79

.65 .73 .77 .80 .86

.75

,85

,90

1_00

1.10

1°20

1,25

1,35

1.50

1.65

1,75

2,00

2.25

2.50

2.75

3.00

3.25

3.50

3,75

4.00

4.50

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.50

9.00

9.50

10.00

10,50

11.00

12.00

.84

.95

1,01

1,12

1.23

1.34

1.39

1,51

1.68

1.84

1.96

2,24

2.52

2.80

3.07

3.35

3.63

3.91

4.19

4.47

5.04

5,59

6,15

6,71

7.26

7.82

8.38

8.94

9.50

10.06

10,60

11.18

11.74

12,30

13.42

.89

1.01

1.07

1.18

1,30

1,42

1.48

1.60

1,77

1,95

2.07

2.37

2,66

2.96

3.25

3.55

3.85

4,14

,92

1.04

1,10

t,23

1.35

1.47

1,53

1.65

1.84

2.02

2.14

2,45

2,76

3.06

3.37

3,67

3.98

4.29

,99

1.13

1.19

1,32

1.46

1.59

1,65

1.79

1,98

2,18

2.32

2.65

2.98

3,31

3.64

3,97

4.30

4.63

4.44

4,73

5,32

5.92

6,51

7.10

7.69

8,28

8.87

9.47

10,06

10.65

11.24

11.83

12.42

13.02

14.20

4.59

4.90

5.51

6.12

6.74

7.35

275 300

.66 169

.83 ,87

1,00 1,04

1.08 1.13

1.24 1.30

1,41 1,47

1,49 1.56

1.66 1.73

1,82 1,91

1.99 2.08

2.17

2,34

2.60

2,66

3.03

3.46

3,90

4.33

4,76

5.20

5.63

6,06

6,50

6,93

7.79

8.66

9.53

10.39

11.26

12.12

12.99

13,86

14.72

15,59

16.45

17.32

18,19

19.05

20.79

7.96

8.57

9.19

9.80

10.41

11,02

11,64

12,25

12_86

13.47

14.70

4.96

5.29

5.95

6,61

7.27

7.94

8,60

9,25

9.91

10.58

11,27

11.91

12.60

13.23

13.89

14.55

15,88

FIGURE 71 Nozzle manufacturers' codesand nozzlecapacities

200

.56

,71

.85

.92

1.06

1.20

1.27

1,41

1,56

1.70

1.77

1.91

2,12

2.33

2.48

2.83

3.18

3.54

3.90

4,24

4,60

4.95

5.30

5,66

6.36

7.07

7.78

8,49

9.19

9,90

10,61

11,31

12.02

12,73

13,44

14.14

14.85

15.56

16,97

250

.63

.79

.95

t .03

1.19

1.34

1.42

1,58

1,74

1.90

1.98 2.07

2.14 2.24

2.37 2,49

2.61 2.73

2.77 2,90

3_16 3.32

3.56 3.73

3.95 4,15

4.35 4.56

4.74 4.97

5.14 5.39

5.53 5.80

5.93 6.22

6.32 6,63

7.11 7.46

7.91 8.29

8,70 9.12

9.49 9,95

10.28 10.78

11,07 11.61

11.86 12,44

t2.65 13.27

13A4 14.10

14.23 14.93

15.02 15,75

15.81 16.58

16.60 17.41

17.39 18,24

18.97 19.90

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FormNo. 6380R97

Printed in U.S.A.

Beckett AFG User Manual BURNER Manuals And Guides L0805145

BECKETT Burner, Furnace Manual L0805145 BECKETT Burner, Furnace Owner's Manual, BECKETT Burner, Furnace installation guides

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