Lennox International Inc G50Uh 24A 045 Users Manual

LENNOX Furnace/Heater, Gas Manual L0806179 LENNOX Furnace/Heater, Gas Owner's Manual, LENNOX Furnace/Heater, Gas installation guides

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,1_2006 Lennox industries

INSTALLATION
INSTRUCTIONS

Inc.

Dallas, Texas, USA

G50UH(X) Series
GAS FURNACE
505,254M
8/2006
Supersedes 504,957M

_
Technical
.L_._L Publications
Lithe U.S.A.

Unit Dimensions ................................
G50UH(X) Parts Arrangement ....................
G50UH(X) Gas Furnace ..........................
Shipping and Packing List ........................
Safety Information ...............................
General ........................................
Combustion, Dilution & Ventilation Air ..............
Setting Equipment ...............................
Filters ..........................................
Duct System ....................................
Venting ........................................
Gas Piping .....................................
Electrical .......................................
Unit Start-Up ...................................
Gas Pressure Adjustment ........................
High Altitude Information .........................
Other Unit Adjustments ..........................
Service ........................................
Repair Parts List ................................
Ignition Control Board Diagnostic Codes ...........
Troubleshooting .................................
Start-Up & Performance Check List ................

RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE

2
3
4
4
4
5
6
8
12
12
12
20
21
25
26
27
27
28
30
30
31
35

&WARNING

Do not store or use gasoline or other
flammable
vapors and liquids in the
vicinity
of this or any other appliance.
Installation
and service
must be
performed
by a qualified installer,
service agency or the gas supplier.

WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Do not touch any electrical switch; do not
use any phone in your building.
• Leave the building immediately.
• Immediately
call your gas supplier from a
neighbor's phone. Follow the gas supplier's
instructions.
• If you cannot reach your gas supplier, call
the fire department.

08/06

IIIHIININIIIIIIIIIIIIIIIIIIIIIIIIIIII

505,254M
Page1

IIIHIIIIIIIIIIIIIIIIIIINII

1 NOTE - 60C and 60D size units that require air volumes
over 1800 cfm (850 L/s) must have one of the following:
1. Single side return air with transition, to accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) air filter. Required to
maintain proper air velocity across the filter.
2. Single side return air with optional RAB Return Air Base
3. Bottom return air.
4. Return air from both sides.
5. Bottom and one side return air.
See Blower Performance Tables for additional information.

3-3/4 (95)-I_ 1

SUPPLY AIR
OPENING

FLUE OUTLET
(Top)

1OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)

2 Flue outlet may be horizontal but furnace must be
vented vertically
3 Optional External Side Return Air Filter Kit is not for use
with the optional RAB Return Air Base.

23-3/4 (603)
I_1

25 (635)
TOP VIEW

TOP VIEW
,_

28-1/2
(724)

3-1/4 (83) Right
8-1/8 (206) Left

A -_
B _

4-9/16

9/16

r--

(14)

iE OUTLET
(Either Side)
/" ........... h r ........... h ::::::::h

ELECTRICAL

f ..............

13-1/4 (337) Left
3 OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)

__
__
....

(Either Side)
o

40
(1016)

GAS PIPING INLET

4-7/8 (124) Right
2-1/4 (57) Left -I_

(Either Side)
ELECTRICAL
OW

INLET

(Either Side)

'
I

[102

(584)
1 OPTIONAL

L RETURN
(Either CUTOUT
Side)

AiR FLOW
!1

(3_6)
1-15/16 (49)

5/8 (16)
4-1/4
(108)

1 Bottom Return
Air Opening
FRONT VIEW
A
Model No.

23 -1/2
(597)
1 Bottom Return
Air Opening
SIDE VIEW

in.

G50UH-24A-045,
G50UH-24A-070,
G50UH-36A-070

14-1/2

368

13-3/8

340

330

4-1/2

114

G50UH-36B-090,
G50UH-48B-090

17-1/2

446

16-3/8

416

406

152

G50UH-48C-110,
G50UH-48C-135,
G50UH-60C-110

533

19-7/8

504

19-1/2

495

7-3/4

197

G50UH-60D-135,
G50UH-60D-155

24-1/2

622

23-3/8

546

584

9-1/2

241

G50UH-36C-110,

Page 2

Air Deflector
G50UH-48C-135,
G50UH-60C-110
&
G50UH-60D-155
UnitsOnly

FlueBoxGasket
HeatExchanger
Gasket

FlueCollectorBox

FlueTransition

Combustion Air
Orifice
Combustion Air
Pressure Switch
Air Inducer
Limit Shield

Flame Sensor _
Flame Rollout Switches*
Flame Rollout Bracket

Primary Limit

Gas Valve

NOx Insert
(NO x Units Only)

Gas Orifices
Ignitor Bracket

Ig'_itor

Secondary Limit
Burner Bottom Shield
Control Transformer

_'_

SureLight ¢ Control Board _'_
"135 and 155 kBtuh units only -Flame rollout switches are located
on brackets on the inner sides (one
on the left and one on the right) of
the burner box.

Blower Assembly
" Capacitor

Door Interlock Switch

FIGURE 1

Page 3

TheG50UH(X)
gasfurnaceis shippedreadyforinstallationintheupfiowor horizontalposition(leftor right).The
furnaceisshippedwiththebottompanelinplace.Thebottompanelmustberemovediftheunitistobeinstalledina
horizontal
application.
Thepanelmayalsoberemovedin
upfiowapplications.

In the USA, installation of gas furnaces must conform with
local building codes. In the absence of local codes, units
must be installed according to the current National Fuel
Gas Code (ANSI-Z223.1/NFPA 54). The National Fuel Gas
Code is available from the following address:
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
In Canada, installation must conform with current National
Standard of Canada CSA B149 Natural Gas and Propane
Installation Codes," local plumbing or waste water codes
and other applicable local codes.

Package 1 of 1 contains

Adequate clearance must be made around the air openings into the vestibule area. In order to ensure proper unit
operation, combustion and ventilation air supply must be

1 - Assembled G50UH(X) unit
1 - Bag assembly containing the following:
2 - Screws
3 -Wire nuts

provided according to the current National Fuel Gas Code
or CSA B149 standards.

1 - Snap bushing
1 - Snap plug
1 - Wire tie

Vent installations must be consistent with the venting
tables (in this instruction) and applicable provisions of local
building codes.

1 -Vent warning label
1 - Owner's manual and warranty card

This furnace is CSA Intemational certified for installation
clearances to combustible material as listed on the unit

The following items may be ordered separately:
1- Thermostat
11111-

nameplate and in the tables in figures 6 and 11. Accessibility
and service clearances must take precedence over fire
protection clearances.

Hanging bracket (for horizontal installations)
Propane/LP changeover kit
High altitude kit
Return air base
Side filter kit

NOTE-

For installation on combustible floors, the furnace

shaft not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.

Check equipment for shipping damage, If you find any
damage, immediately contact the last carrier.

For installation in a residential garage, the furnace must
be installed so that the burner(s) and the ignition source
are located no less than 18 inches (457 mm) above the
floor. The furnace must be located or protected to avoid
physical damage by vehicles. When a furnace is installed
in a public garage, hangar, or other building that has a hazardous atmosphere, the furnace must be installed according to recommended good practice requirements and current National Fuel Gas Code or CSA B149 standards.

A,WARNING

NOTE - Furnace must be adjusted to obtain a temperature
rise within the range specified on the unit nameplate. Failure
to do so may cause erratic limit operation.
This G50UH(X) furnace must be installed so that its electrical components are protected from water.

A,CAUTION

G50UH(X) units are CSA International certified to ANSI
Z21.47 and CSA 2.3 standard.

When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
With a parallel flow arrangement, a damper (or other
means to control the flow of air) must adequately prevent
chilled air from entering the furnace. If the damper is manually operated, it must be equipped to prevent operation of
either the heating or the cooling unit, unless it is in the full
HEAT or COOL setting.

Page 4

Wheninstalled,
thisfurnacemustbeelectrically
grounded
according
tolocalcodes.Inaddition,intheUnitedStates,
installationmustconformwiththecurrentNationalElectricCode,ANSI/NFPA
No.70.TheNationalElectricCode
(ANSI/NFPA
No.70) is availablefromthe followingaddress:
NationalFireProtection
Association
1 BatteryMarchPark
Quincy,MA02269
InCanada,allelectricalwiringandgrounding
fortheunit
mustbeinstalled
according
tothecurrentregulations
ofthe
CanadianElectricalCodePartI (CSAStandardC22.1)
and/orlocalcodes.
NOTE - This furnace is designed for a minimum continuous return air temperature of 60°F (16°C) or an intermittent operation down to 55°F (13°C) dry bulb for cases
where a night setback thermostat is used. Return air temperature must not exceed 85°F (29 °C) dry bulb.
The G50UH(X) furnace may be installed in alcoves, closets, attics, basements, garages, and utility rooms in the upflow or horizontal position.

• The furnace heat exchanger, components, duct system,
air filters and evaporator coils must be thoroughly
cleaned following final construction clean-up.
• All furnace operating conditions (including ignition, input rate, temperature rise and venting) must be verified
according to these installation instructions.
NOTE - The Commonwealth
of Massachusetts
lates these additional requirements:

stipu-

• Gas furnaces shall be installed by a ticensedptumber or gas fitter only.
• The gas cock must be "T handle"

type.

• When a furnace is installed in an attic, the passageway to and service area surrounding the equipment
shall be floored.

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.

This furnace design has not been CSA International certified for installation in mobile homes, recreational vehicles,
or outdoors.

In addition to the requirements outlined previously, the following general recommendations must be considered
when installing a G50UH(X) furnace:

Lennox does not recommend the use of G50UH units as a

• Place the furnace as close to the center of the air dis-

construction heater during any phase of construction. Very
low return air temperatures, harmful vapors and operation
of the unit with clogged or misplaced filters will damage the
unit.

tribution system as possible. The furnace should also be
located close to the chimney or vent termination point.

G50UH units may be used for heating of buildings or structures under construction,
met:

if the following

conditions are

• The vent system must be permanently installed per
these installation instructions.
• A room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
allowed.
• The return air duct must be provided and sealed to the
furnace.
• Return air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.
• Air filters must be installed in the system and must be
maintained during construction.
• Air filters must be replaced upon construction completion.
• The input rate and temperature rise must be set per the
furnace rating plate.
• One hundred percent (100%) outdoor air must be provided for combustion air requirements during construction. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.
Page 5

• Do not install the furnace where drafts might blow directly into it. This could cause improper combustion and unsafe operation.
• Do not block the furnace combustion air openings with
clothing, boxes, doors, etc. Air is needed for proper
combustion and safe unit operation.
• When the furnace is installed in an attic or other insulated space, keep insulation away from the furnace.

WARNING

Inthepast,therewasnoproblem
inbringinginsufficient
outdoorairforcombustion.
Infiltration
provided
alltheairthat
wasneeded.Intoday'shomes,tightconstruction
practices
makeit necessary
to bringin airfromoutsideforcombustion.Takeintoaccountthatexhaustfans,appliance
vents,
chimneys,
andfireplaces
forceadditional
airthatcouldbe
usedforcombustion
outofthehouse.Unlessoutsideairis
broughtintothe housefor combustion,
negativepressure
(outsidepressure
is greaterthaninsidepressure)
willbuild
tothepointthata downdraft
canoccurinthefurnacevent
pipeorchimney.
Asa result,combustion
gasesenterthelivingspacecreatinga potentially
dangerous
situation.
Intheabsenceoflocalcodesconcerning
airforcombustionandventilation,
usetheguidelines
andprocedures
in
thissectiontoinstallG50UH(X)
furnaces
toensureefficient
andsafe operation.Youmustconsidercombustionair
needsandrequirements
forexhaustventsandgaspiping.
A portionof thisinformation
hasbeenreprintedwithpermissionfromtheNationalFuelGasCode(ANSI-Z223.1).
Thisreprinted
materialisnotthecomplete
andofficialpositionoftheANSIonthereferenced
subject,whichis representedonlybythestandardin itsentirety.
In Canada,referto the standardCSAB149installation
codes.

ACAUTION

All gas-fired appliances require air for the combustion process. If sufficient combustion air is not available, the furnace or other appliances will operate inefficiently and unsafely. Enough air must be provided to meet the needs of all
fuel-burning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, exhaust fans, or clothes dryers are used at the same time as
the furnace, much more air is necessary to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result in carbon
monoxide,
In addition to providing combustion air, fresh outdoor air
dilutes contaminants in the indoor air. These contaminants may include bleaches, adhesives, detergents, solvents and other contaminants which can corrode furnace
components,
The requirements for providing air for combustion and ventilation depend largely on whether the furnace is installed in
an unconfined or a confined space,
Unconfined

Space

An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not
separated by a door. Though an area may appear to be unconfined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the air
from outside section.
Confined

Space

A confined space is an area with a volume less than 50 cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the
combined input rating of all appliances installed in that
space. This definition includes furnace closets or small
equipment rooms.
When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space containing the furnace, the return air must be handled by ducts
which are sealed to the furnace casing and which terminate
outside the space containing the furnace, This is especially
important when the furnace is mounted on a platform in a
confined space such as a closet or small equipment room.
Even a small leak around the base of the unit at the platform
or at the return air duct connection can cause a potentially
dangerous negative pressure condition, Air for combustion
and ventilation can be brought into the confined space either
from inside the building or from outside,

Page 6

Air from Outside

EQUIPMENT IN CONFINED
SPACE ALL AIR FROM INSIDE

CHIMNEY

If air from outside is brought in for combustion and ventilation, the confined space must have two permanent open-

VENT

ings. One opening shall be within 12 inches (305 mm) of the
top of the enclosure and one opening within 12 inches (305
mm) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a minimum
free area of 1 square inch (645 mm 2) per 4,000 Btu (1.17
kW) per hour of total input rating of all equipment in the enclosure. See figures 3 and 4. When communicating with
the outdoors through horizontal ducts, each opening shall
have a minimum free area of 1 square inch (645 mm 2) per
2,000 Btu (.56 kW) per total input rating of all equipment in

HEATER
FURNACE

OPENINGS
(To Adjacent
Room)

WiTER
/
I I

I I

NOTE - Each opening shall have a free area of at least one square
inch (645 mm 2) per 1,000 Btu (.29 kW) per hour of the total input rating of all equipment in the enclosure, but not less than 100 square
inches (64516 mm2).

the enclosure. See figure 5.

FIGURE 2
Air from Inside
If the confined space that houses the furnace adjoins a
space categorized as unconfined, air can be brought in by
providing two permanent openings between the two
spaces. Each opening must have a minimum free area of 1
square inch (645 mm 2) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas-fired equipment in the confined
space. Each opening must be at least 100 square inches
(64516 mm2). One opening shall be within 12 inches (305
mm) of the top of the enclosure and one opening within 12
inches (305 mm) of the bottom. See figure 2.

When ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens must
be considered. If the design and free area of protective covering is not known for calculating the size opening required,
it may be assumed that wood louvers will have 20 to 25 percent free area and metal louvers and grilles will have 60 to
75 percent free area. Louvers and grilles must be fixed in the
open position or interlocked with the equipment so that they
are opened automatically during equipment operation.

EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(Inlet Air from Crawlspace and Outlet Air
to Ventilated Attic)

CHIMNEY OR
GAS VENT

VENTILATION
LOUVERS
(Each end of attic)
I ......

OUTLET
AIR

FURNACE

VENTILATION
LOUVERS
(For unheated

WATER
HEATER

INLET
AIR

crawl !

NO TE- The inlet and outlet air openings shall each have a free area of at least one square inch (645
mm 2) per 4, 000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.

FIGURE 3

Page 7

EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)

CHIMNEY
OR GAS
VENT_

VENTILATION
LOUVERS
(Each end of attic)

FURNACE

INLET AIR
(Ends 12 in.
above bottom)

HEATER

NO TE- The inlet and outlet air openings shall each have a
free area of at least one square inch (645 mm 2) per 4,000
Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.

_
JJ_

Select a location that allows for the required clearances
that are listed on the unit nameplate. Also consider gas
supply connections, electrical supply, vent connection,
and installation and service clearances [24 inches (610
mm) at unit front]. The unit must be level.
NOTE - 1/3 hp blower motors are equipped with four flexible mounting legs. 1/2 hp blower motors are equipped with
three flexible legs and one rigid leg. The rigid leg is
equipped with a shipping bolt and a flat white plastic washer (rather than the rubber mounting grommet used with a
flexible mounting leg). The bolt and washer must be removed before the furnace is placed into operation. After the bolt and washer have been removed, the rigid leg
will not touch the blower housing.
Upflow Applications
Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or alcove installations are shown in figure 6.

FIGURE 4
A
TT'_.

The G50UH(X) gas furnace can be installed as shipped
in either the upfiow position or the horizontal position,
with right-hand or left-hand air discharge.

EQUIPMENT IN
CONFINED SPACE

I I "_'Y

Upflow

Application

Installation

Clearances

ALLAIRFROM
Top

I1
I1"- ,,
OUTLET

AIR

Left Side

Right

Side

FURNACE

Bottom

NOTE - Each air duct opening shall have a free area of at least
o ne square inch (645 mm 2J per 2, 000 Btu (.59 kW) per hour of
the total input rating of all equipment in the enclosure. If the
equipment room is located against an outside wall and the air
openings communicate directly with the outdoors, each opening shall have a free area of at least one square inch (645 mm 2)
per4,000 Btu (1.17 kW) per hour of the total input rating of all
other equipment in the enclosure.

FIGURE 5

Type of Vent
Connector

Type C

Type B1

Top

1 in, (25 ram)

*Front

3 in, (76 ram)

Back

Sides

Vent

6 in. (152 ram)

1 in. (25 ram)

Floor

0J;

*Front clearance in alcove installation must be 24 in. (610 ram).
Maintain a minimum of 24 in. (610 ram) for front service access.
SFor installation on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
l-Left side requires 3 inches ifa single wall vent is used on 14-1/2
inch cabinets, or 2 inches if a single wall vent is used on 17-1/2
inch cabinets.

-&WARNING

FIGURE 6

Page 8

Return
Return

Air -- Upflow

air can be brought

in through

side of the furnace

installed

furnace

on a platform

is installed

an airtight
platform

seal between
to ensure

safely. The furnace
panel to facilitate
Markings
cabinet

required
tion,

with bottom

the bottom

is equipped

If the

Side Return Air
(with transition and filter)

return, make

of the furnace
operates

Refer to Engineering Handbook for additional information.

or either

and the

properly

with a removable

and

bottom

installation,

20" X 25" X 1"

on both sides of the furnace

that require

at the maximum

NOTE - When

the bottom

in an upflow application.

that the furnace

are provided

for installations

5 - Return air from bottom and one side.

Applications

side return air. Cut the furnace

dimensions

air volumes

over

with 60C or 60D models

the following

(508mm X635mm X 25mm)
Cleanable Filter

cabinet

return

shown on page 2.
1800 cfm (850 L/s) are
in an upflow

air options

applica-

are available:

Return Air
Plenum

1 - Return air from single side with transition which will
accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter. (Required to maintain proper air velocity.)
See figure 7.
2 - Return air from single side
Air Base. See figure 8.

with optional

RAB Return

Transition

3 - Return air from bottom.

FIGURE 7

4 - Return air from both sides.

(Upflow Applications

Optional Return Air Base
Only -- For use with B, C and D cabinets only)

41
14

(102)1"9_-

123(584)
Overall
(Maximum)

AIR FLOW

1 Unit Opening
side return air

24-1/2

(622) RAB-D

(98M59)

11 (279)
2 Maximurr
11_5.6)
_
__ j

1 22-7-16
(570)
Overall
Maximum)

5 -5/8

7-1/4 (184)

17-1/2 (446) RAB-B (98M60)
21 (533) RAB-C (98M58)

fL_1 MinimuV_

(143)

_-3/4
.....................
_
23 (584)....................................................................
_!

OPTIONAL RAB
RETURN AIR BASE

(19)

7/8
(22)

_1--

27-5/8 (702)
SIDE VIEW

FRONT VIEW
NOTE- Optional
Side Return Air Filter Kits are not for use with RAB Return Air Base.
1 Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.
Minimum unit side return air opening dimensions
for units requiring 1800 cfm or more of air (W x H): 23 x 11 in.
(584 x 279 mm).
The opening can be cut as needed to accommodate
plenum or IAQ cabinet while maintaining
dimensions shown.
Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return
air opening. The size of the opening must not extend beyond the markings on the furnace cabinet..
2 To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.
NOTE- Optional Side Return Air Filter Kits are not for use with RAB Return Air Base.

FIGURE 8

Page 9

Removingthe

Bottom Panel

Leveling Bolt Installation

Remove the two screws that secure the bottom cap to the
furnace. Pivot the bottom cap down to release the bottom
panel. Once the bottom panel has been removed, reinstall
the bottom cap, See figure 9.

Inches (mm)

3/8

(10) _r
Furnace Front

_'1 [

3/8

1-3/4
(44)

Removing the Bottom Panel
1-3/4
(44)

Leveling Bolt
Locations

Furnace
Bottom

3/8
(10)

Leveling Bolt
Locati_

1-3/4
(44)

3/8

(10)
I-3/4 (44)

FIGURE 10
Screw

Horizontal

Applications

The G50UH(X) furnace can be installed in horizontal applications,

\/
Bottom Cap

Allow for clearances to combustible materials as indicated
on the unit nameplate, Minimum clearances for closet or alcove installations are shown in figure 11,

Bottom

Horizontal Application
Installation Clearances

FIGURE 9

Top
Leveling an Upflow Unit
When the side return air inlets are used in an upflow application, it may be necessary to install leveling bolts on the

Left End

bottom of the furnace. Use field-supplied corrosion-resistant 5/16 inch machine bolts (4) and nuts (8), See figure 10.

Right End

Bottom
Vent Connector
Type

NOTE - The maximum length of the bolt is 1-1/2 inches.
1 - Lie the furnace on its back and drill a 5/16 inch diame-

Type C

Type

ter hole in each corner of the furnace's bottom. See figure 10 for the correct location of the holes, Drill through
the bottom panel and the bottom flange of the cabinet,

Top

*Front

3 in. (76 ram)

Back

2 - Install one bolt and two nuts into each hole. Screw the
first nut onto a bolt and then insert the bolt into a hole, A

Ends

2 in. (51 ram)

Vent

fiat washer may be added between the nut and the bottom of the unit,
3 - Screw another nut onto the bolt on the inside of the furnace base. A flat washer may be added between the
nut and the bottom of the unit,
4 - Adjust the outside nut to the appropriate height and
tighten the inside nut to secure the arrangement,

Floor

6 in. (152

ram)

o:_

1 in. (25 ram)

o:_

*Front clearance in alcove installation must be 24 in. (610 ram).
Maintain a minimum of 24 in. (610 ram) for front service access.
_:For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.

Page 10

FIGURE 11

Thisfurnacemaybeinstalledineitheranatticora crawlspace.Eithersuspendthe furnacefromroof raftersor
floorjoists,asshowninfigure12,orinstallthefurnaceon
a platform,as shownin figure13.Theunitmustbesupportedat bothendsandbeneaththeblowerdecktopreventsagging.

Horizontal Application
Unit Installed on Platform
NOTE - Line contact is permissible. See the unit nameplate for
clearances.
\

\
\

Typical Horizontal Application
Unit Suspended in Attic or Crawlspace

GAS
ENTRY

Leave sufficient clearance between rod and unit to
remove access panel.

__VENT
PIPE

WORKING
PLATFORM

FIGURE 13
1/4 i

-&WARNING
ANGLE
IRON

U-CHANNELS

FIGURE 12
NOTE - Heavy-gauge perforated sheet metal straps
(plumbers' straps) may be used to suspend the unit from
roof rafters or ceiling joists. When straps are used to suspend the unit in this way, support must be providedfor both
the ends and the middle of the furnace to prevent sagging.
The straps must not interfere with the plenum or exhaust
piping instaflation. Securing screws should be 1/2 inch
from the top edge and 1-1/2 inch from the side edge in aft
cases. Cooling coils and supply and return air plenums
must be supported separately.
NOTE - When the furnace is installed on a platform in a
crawlspace, it must be elevated enough to avoid water
damage and to allow the evaporator coil to drain.
Return Air -- Horizontal

Applications

Return air can be brought in through the end of a furnace
installed in a horizontal application, The furnace is
equipped with a removable bottom panel to facilitate
installation, See figure 9,

Page 11

&WARNING

Thisunitis notequippedwitha filteror rack.A field-providedhigh-velocity
filteris requiredfortheunittooperate
properly.Table1 listsrecommended
filtersizes.
Afiltermustbein placeanytimetheunitisoperating.
TABLE 1
Furnace
Cabinet Size

Filter Size
Side Return

Bottom Return

14-1/2"

16X25X

1 (1)

17-112"

16X25X

1 (1)

16X25X1

21"

16X25X

1 (1)

20X25X

1 (1)

16 X 25 X 1 (2)

24X25X

1 (1)

24-1/2"

14X25X1

(1)
(1)

A 4-inch diameter flue transition is factory-installed on the
combustion air inducer outlet of all models. Modifying or
removing the flue transition will cause the unit to operate unsafely and will void the unit certification.
The
vent connector does not require insulation.
The combustion air inducer may be rotated clockwise or
counterclockwise by 90 ° to allow for top or side vent discharge in all applications. When the unit is installed, the flue
transition must be in the 9 o'clock, 12 o'clock or 3 o'clock
position. The unit will not vent properly with the flue
transition pointed down in the 6 o'clock position. Remove the four mounting screws, rotate the assembly (including the gasket), then reinstall the mounting screws.
See figure 14. Use the provided wire tie to bundle the pressure switch wires with the inducer motor power leads.
Route the wires away from moving parts and the heat
of the inducer motor to prevent damage to the wires.

Use industry-approved standards to size and install the
supply and return air duct system. This will result in a quiet
and low-static system that has uniform air distribution.

Combustion

Air Inducer

NOTE - Do not operate the furnace with an external static
pressure that exceeds 0,5 inches w,c, Higher external static pressures may cause erratic limit operation,
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable
access panel must be installed in the supply air duct, The
access panel should be large enough to permit inspection
(either by smoke or reflected light) of the heat exchanger
for leaks after the furnace is installed, The furnace access
panel must always be in place when the furnace is operating and it must not allow leaks into the supply air duct system,

Flue Transition
(Do not remove)

Mounting Screws
(Remove)

Return Air Plenum

FIGURE

Return air must not be drawn from a room where this
furnace, or any other gas appliance (ie., a water heater), is installed. When return air is drawn from a room, a
negative pressure is created in the room, If a gas appliance is operating in a room with negative pressure, the
flue products can be pulled back down the vent pipe and
into the room, This reverse flow of the flue gas may result
in incomplete combustion and the formation of carbon
monoxide gas. This toxic gas might then be distributed
throughout the house by the furnace duct system,
In upflow applications, the return air can be brought in
through the bottom or either side of the furnace. If a furnace with bottom return air is installed on a platform, make
an airtight seal between the bottom of the furnace and the
platform to ensure that the unit operates properly and
safely, Use fiberglass sealing strips, caulking, or equivalent sealing method between the plenum and the furnace
cabinet to ensure a tight seal, Ifa filter is installed, size the
return air duct to fit the filter frame.

Page 12

Power Leads
14

Optional Flue Outlet
(Horizontal Installation)
Top View of Furnace
Top Cap ----__ _
Flue Outlet
Hole /
(Reattach
Cutout Here)

_<_J
II 111

Supply Air
Opening

Optional
Flue Outlet

FIGURE 15

Usesheetmetalshearstoremove
thecutoutfromtheside
ofthecabinet.Usethetwoprovided
sheetmetalscrewsto
installthecutoutonthetopcaptocovertheoriginalflue
outletopening.Seefigure15.
TheG50UH(X)
seriesunitsareclassified
as fan-assisted
CategoryI furnaceswhenverticallyventedaccordingto
thelatesteditionof NationalFuelGasCode(NFPA54 /
ANSI Z223.1 ) in the USA and the current standards of CSA
B149 Natural Gas and Propane Installation Codes in Canada. A fan-assisted Category I furnace is an appliance
equipped with an integral mechanical means to either draw
or force combustion products through the combustion
chamber and/or heat exchanger.
NOTE - Use these instructions as a guide. They do not supersede local codes. This furnace must be vented according to all local codes these installation instructions, and the
provided venting tables in these instructions
The venting tables in this manual were extracted from the
National Fuel Gas Code (NFPA 54 / ANSI Z223.1 ) and are
provided as a guide for proper vent installation. Proper application, termination, construction and location of vents
must conform to local codes having jurisdiction. In the absence d local codes, the NFGC serves as the defining document.
Refer to the tables and the venting information contained in
these instructions to properly size and install the venting
system.

klMPORTANT

flue transition. If self-drilling screws are used to attach the
vent pipe, it is recommended that three be used. Drive one
self-drilling screw through the front and one through each
side of the vent pipe and collar. See figure 16.
Install the first vent connector elbow at a minimum of six
inches (152 mm) from the furnace vent outlet.
Venting Using a Masonry Chimney
The following additional requirements apply when a lined
masonry chimney is used to vent this furnace.
Masonry chimneys used to vent Category I central furnaces must be either tile-lined or lined with a listed metal
lining system or dedicated gas vent. Unlined masonry
chimneys are prohibited. See figures 17 and 18 for common venting.
A chimney with one or more sides exposed to the outside of
the structure is considered to be an exterior chimney.
An exterior masonry chimney that is not tile-lined must be
lined with B1 vent or a listed insulated flexible metal vent.
An exterior tileqined chimney that is sealed and capped
may be lined with a listed uninsulated flexible metal vent.
If the existing chimney will not accommodate a B1 vent or
an insulated flexible vent pipe liner, either the chimney
must be rebuilt to accommodate one of these liners or an
alternate approved venting method must be found.
Insulation for the flexible vent pipe must be an encapsulated fiberglass sleeve recommended by the flexible vent
pipe manufacturer. See figure 17.
G50UH units installed in upflow applications may be
vented into a tile-lined masonry chimney without using a
listed metal liner, provided that the optional masonry chimney vent adapter kit (18M79) is used. Instructions provided
with the kit must be followed exactly.
DO NOT insulate the space between the liner and the
chimney wall with puffed mica or any other loose granular insulating material
Common Venting Using Metal-Lined Masonry Chimney

kWARNING

SEALED

/
T

VENT CONNECTION

MAX. LENGTH
-- SEE NOTE 1
BELOW.

II
II

VE%OO.o%OTOR "

VENT
PIPE

EXTERIOR
WITH

CHIMNEY

METAL

LINER

'1
__

.,J

PERMANENTLY
SEALED FIREPLACE
OPENING

FURNACE
FLUE TRANSITIOF
COLLAR

FIGURE 16
Use self-drilling sheet metal screws or a mechanical fastener to firmly secure the vent pipe to the round collar of the
Page 13

NOTE 1 - Refer to the provided venting tables for installations in the USA
and the venting tables in CSA B149 for installations Canada.
NOTE 2 - Either single-walled
or double-walled vent connector may be
used. Refer to the capacity requirements shown in the provided venting
tables for installations in USA and the venting tames in current CSA
B149 for installations in Canada.

FIGURE 17

Common

Venting

Using Tile-Lined

Interior

Masonry

Chimne

' and Combined

Vent Connector

MINIMUM LENGTH = AS SHORT AS PRACTICAL.
FOR MAXIMUM
LENGTH SEE NOTE TO LEFT

NOTE- Refer to provided venting tables
for installations in the USA and the

venting tables in current CSA B149 for

installations

in Canada.

INTERIOR TILE=LINED
MASONRY CHIMNEY

NOTE - the chimney must be properly
sized per provided venting tables or
lined with listed metal lining system.

_
m

FU
OTHER
APPLIANCE

PERMANENTLY
SEALED FIREPLACE
OPENING

_Row

NOTE - Either single-walled or double-walled vent connector may be used. Refer to the capacity requirements as shown in the provided venting tables for installations in USA and the venting tables in current CSA B149 for installations in Canada.

FIGURE 18
Never connect a Category I appliance to a chimney that is
servicing a solid-fuel appliance. If a fireplace chimney flue
is used to vent this appliance, the fireplace opening must
be permanently sealed.
A type B or listed chimney lining system that passes
through an unused masonry chimney flue is not considered
to be exposed to the outdoors.
General Venting Requirements
Vent all G50UH(X) furnaces according to these instructions:
A fan-assisted furnace may be commonly vented into an
1 - Vent diameter recommendations and maximum allowexisting lined masonry chimney if the following conditions
able piping runs are found in the provided venting tables
are met:
for the USA, and the appropriate venting tables in the
• The chimney is currently serving at least one drafthood
standards of CSA B149 Natural Gas and Propane
equipped appliance
Installation Codes for Canada.
• The vent connectors and chimney are sized accord2 - In no case should the vent or vent connector diameter
ing to the provided venting tables for the USA, and
be less than the diameter specified in the provided
the appropriate venting tables in the standards of
venting tables for the USA, and the appropriate venting
CSA B149 Natural Gas and Propane Installation
Codes in Canada.
tables in the standards of CSA B149 Natural Gas and
Propane Installation Codes for Canada.
If type B1 double-wall vent is used inside a chimney, no oth-

,IMPORTANT

er appliance can be vented into the chimney. The outer wall
of type B1 vent pipe must not be exposed to flue products.
A type B1 vent or masonry chimney liner shall terminate
above the roof surface with a listed cap or a listed roof assembly according to the terms of their respective listings
and the vent manufacturer's instructions.
When inspection reveals that an existing chimney is not
safe for the intended purpose, it shall be rebuilt to conform
to nationally recognized standards, lined or relined with
suitable materials, or replaced with a gas vent or chimney
suitable for venting G50UH(X) series units. The chimney
passageway must be checked periodically to ensure that it
is clear and free of obstructions.
Do not install a manual damper, barometric draft regulator,
or flue restrictor between the furnace and the chimney.

3 - Single appliance vents -If the vertical vent or tile-lined
chimney has a larger diameter or flow area than the
vent connector, use the vertical vent diameter to determine the minimum
vent capacity and the vent
connector diameter to determine the maximum vent
capacity, The flow area of the vertical vent, however,
shall not exceed 7 times the flow area of the listed appliance categorized vent area, drafthood outlet area or
flue collar area unless designed according to approved
engineering methods.
4 - Multiple appliance vents - The flow area of the largest
section of vertical vent or chimney shall not exceed 7
times the smallest listed appliance categorized vent
area, drafthood outlet area orflue collar area unless designed according to approved engineering methods.

Page 14

5 - Theentirelengthofsinglewallmetalventconnector
shallbe readilyaccessiblefor inspection,cleaning,
andreplacement.
6 - Singleappliance
ventingconfigurations
withzerolaterallengths(tables3 and4) areassumedto haveno
elbowsintheventsystem.Forallotherventconfigurations,theventsystemisassumedtohavetwo90° elbows.Foreachadditional
90°elbowor equivalent
(for
exampletwo45°elbowsequalone90°elbow)beyond
two,the maximumcapacitylistedintheventingtable
shouldbereduced
by 10%(0.90x maximum
listedcapacity).
7 - Thecommonventingtables(5,6,7,and8)weregeneratedusinga maximumhorizontalventconnector
lengthof 1-1/2feet(.46m)foreachinch(25mm)of
connector
diameterasfollows:
TABLE 2

Connector Diameter
inches (mm)

Maximum Horizontal
Connector Length feet (m)

3 (76)

4-1/2 (1.37)

4 (102)

6 (1.83)

5 (127)

7-1/2 (2.29)

6 (152)

9 (2.74)

7 (178)

10-1/2 (3.20)

means, except vent connectors of listed type B vent
material which shall be assembled according to the
manufacturer's instructions. Joints between sections
of single wall connector piping shall be fastened by
screws or other approved means.
12- When the vent connector used for Category I appliances must be located in or pass through a crawlspace or other areas which may be cold, that portion of
the vent connector shall be constructed of listed
double-wall type B vent material or material having
equivalent insulation qualities.
13 - All venting pipe passing through floors, walls, and ceilings must be installed with the listed clearance to combustible materials and be fire stopped according to local codes. In absence of local codes, refer to NFGC
(Z223.1).
14 - No portion of the venting system can extend into, or pass
through any circulation air duct or plenum.
15 - Vent connectors serving Category I appliances shall
not be connected to any portion of mechanical draft
systems operating under positive pressure such as
Category III or IV venting systems.

If the common vertical vent is offset, the maximum
common vent capacity listed in the common venting
tables should be reduced by 20%, the equivalent of two
90 ° elbows (0.80 x maximum common vent capacity).
The horizontal length of the offset shall not exceed
1-1/2 feet (.46 m) for each inch (25 mm) of common
vent diameter.

9 - The vent pipe should be as short as possible with the
least number of elbows and angles required to complete the job. Route the vent connector to the vent using the shortest possible route.
10 - A vent connector shall be supported without any dips
or sags and shall slope a minimum of 1/4 inch (6.4 mm)
per linear foot (305 mm) of connector, back toward the
appliance.
11 - Vent connectors shall be firmly attached to the furnace
flue collar by self-drilling screws or other approved

16 - If vent connectors are combined prior to entering the
common vent, the maximum common vent capacity
listed in the common venting tables must be reduced by
10%, the equivalent of one 90 ° elbow (0.90 x maximum
common vent capacity).
17 - The common vent diameter must always be at least as
large as the largest vent connector diameter.
18 - In no case, shall the vent connector be sized more than
two consecutive table size diameters over the size of
the draft hood outlet or flue collar outlet.
19 - Do not install a manual damper, barometric draft regulator or flue restrictor between the furnace and the
chimney.
20 - When connecting this appliance to an existing dedicated or common venting system, you must inspect the
venting system's general condition and look for signs
of corrosion. The existing vent pipe size must conform
to these instructions and the provided venting tables
for the USA, and the appropriate venting tables in the
standards of CSA B149 Natural Gas and Propane
Installation Codes for Canada. If the existing venting
system does not meet these requirements, it must be
resized.

Page 15

TABLE 3
Capacity

Height
H
(feet)

Lateral
L
(feet)

of Type B Double-Wall Vents with Type B Double-Wall Connectors
Serving a Single Category I Appliance
Vent and Connector
4 Inch

3 Inch

Appliance
MIN

Diameter - D (inches)
5 Inch

Input Rating in Thousands
MAX
MIN

of Btu Per Hour
MAX

6 Inch

MIN

MAX

MIN

MAX

152

251

375

157

232

153

227

149

223

165

276

415

109

178

263

103

171

255

164

247

175

295

447

118

194

289

113

187

280

104

176

267

191

327

502

136

226

339

130

219

330

121

206

315

112

195

301

202

349

540

149

250

377

143

242

367

133

229

351

124

217

337

116

206

322

100

213

374

587

166

283

432

160

275

421

150

262

405

141

249

389

132

237

374

113

214

104

346

NOTE - Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other
vent configurations, the vent system is assumed to have two 90 ° elbows. For each additional 90 ° elbow or equivalent (for example two 45 °
elbows equal one 90 ° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).

Page 16

TABLE 4
Capacity of Type B Double-Wall Vents with Single-Wall Metal Connectors
Serving a Single Category I Appliance
Vent and Connector
Height
H
(feet)

Lateral
L
(feet)

3 Inch

Diameter - D (inches)

4 Inch
Appliance
MIN

5 Inch

Input Rating in Thousands
MAX
MIN

MIN

MAX

151

6 Inch

of Btu Per Hour
MAX

MIN

MAX

249

126

373

156

123

231

102

152

146

225

114

147

163

220

164

273

123

412

108

176

121

261

102

107

168

151

252

122

161

175

243

174

293

120

444

117

193

119

287

111

105

185

148

277

100

132

171

188

261

190

325

116

499

136

225

115

337

128

102

216

144

326

116

128

201

182

308

158

186

220

290

200

346

114

537

148

248

113

375

140

100

239

141

363

129

125

223

177

344

155

208

216

325

186

192

254

306

211

372

110

584

164

281

109

429

157

271

136

417

144

122

255

171

397

115

131

151

239

208

377

181

223

246

357

Page 17

TABLE 5
Vent Connector Capacity
Type B Double-Wall Vents with Type B Double-Wall Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)

Vent and Connector

Connector
Rise
R
(feet)

3 Inch

Diameter - D (inches)

4 Inch
5 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN
MAX
MIN
MAX

MIN

MAX

3
1

6 Inch
MIN

MAX

106

164

121

183

132

199

114

176

128

195

139

210

123

189

136

206

146

220

142

220

153

235

102

163

248

157

246

105

167

259

110

176

271

113

181

288

118

190

299

123

198

309

TABLE 6
Common

Type

B Double-Wall

Serving

Two

Vent
with

Capacity

Type B Double-Wall
Connectors
Category I Appliances

Common Vent Diameter

Vent
Height
H
(feet)

Vents

4 Inch

- D (inches)

5 Inch

6 Inch

FAN + FAN

FAN + NAT

Appliance
FAN + FAN

140

116

204

101

155

129

224

110

169

141

125

112

195

136

123

152

138

7 Inch

Input Rating in Thousands of Btu Per Hour
FAN + NAT
FAN + FAN
FAN + NAT

FAN + FAN

FAN + NAT

161

309

248

178

339

275

243

194

367

299

164

283

228

427

352

215

183

314

255

475

394

244

210

361

297

547

459

Page 18

TABLE 7
Vent Connector Capacity
Type B Double-Wall Vents with Single-Wall Metal Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)

Vent and Connector

Diameter - D (inches)

Connector
Rise
R
(feet)

MIN

MAX

2
3

3 Inch

4 Inch
5 Inch
Appliance Input Rating in Thousands of Btu Per Hour
MIN
MAX
MIN
MAX

6 Inch
MIN

MAX

168

182

121

131

174

198

116

138

177

214

121

150

185

230

100

127

160

193

243

110

113

175

169

278

115

117

185

177

290

119

122

193

185

300

TABLE 8
Common Vent Capacity
Type B Double-Wall Vents with Single-Wall Metal Connectors
Serving Two or More Category I Appliances
Common Vent Diameter

Vent
Height

4 Inch

- D (inches)

5 Inch

6 Inch

7 Inch

H
(feet)

FAN + FAN

FAN + NAT

Appliance
FAN + FAN

Input Rating in Thousands of Btu Per Hour
FAN + NAT
FAN + FAN
FAN + NAT

FAN + FAN

FAN + NAT

136

113

200

158

304

244

151

126

218

173

331

269

106

163

137

237

189

357

292

121

108

189

159

275

221

416

343

131

118

208

177

305

247

463

383

145

132

236

202

350

286

533

446

Removal of the Furnace from Common Vent

and other spaces of the building. Turn on clothes dryers and any appliances not connected to the common
venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers,

In the event that an existing furnace is removed from a
venting system commonly run with separate gas appliances, the venting system is likely to be too large to
properly vent the remaining attached appliances,
Conduct the following test while each appliance is operating and the other appliances (which are not operating) remain connected to the common venting system. If the
venting system has been installed improperly, you must
correct the system as indicated in the general venting requirements section,
1 - Seal any unused openings in the common venting system.

4 - Follow the lighting instructions, Turn on the appliance
that is being inspected. Adjust the thermostat so that
the appliance operates continuously,
5 - After the main burner has operated for 5 minutes, test
for leaks of flue gases at the draft hood relief opening,
Use the flame of a match or candle, or smoke from a
cigarette, cigar, or pipe,

leakage, corrosion, or other deficiencies which could
cause an unsafe condition,

6 - After determining that each appliance connected to the
common venting system is venting properly, (step 3)
return all doors, widows, exhaust fans, fireplace dampers, and any other gas-burning appliances to their previous mode of operation,

3 - Close all building doors and windows and all doors between the space in which the appliances remaining
connected to the common venting system are located

7 - If a venting problem is found during any of the preceding tests, the common venting system must be modified to correct the problem,

Inspect the venting system for proper size and horizontal
pitch, Determine that there is no blockage, restriction,

Page 19

Resizethe commonventingsystemto the minimum
ventpipesizedeterminedby usingthe appropriate
tablesin appendixG. (Thesearein thecurrentstandardsoftheNationalFuelGasCodeANSIZ223.1in
theUSA,andtheappropriate
Category1 NaturalGas
andPropaneappliances
ventingsizingtablesin the
currentstandardsof theCSAB149NaturalGasand
PropaneInstallation
CodesinCanada.)

3 - The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters,
or elevator shafts.
4 - The piping should be sloped 1/4 inch (6.4 mm) per 15
feet (4,57 m) upward toward the meter from the furnace. The piping must be supported at proper intervals
[every 8 to 10 feet (2.44 to 3.01 m)] with suitable hangers or straps, Install a drip leg inside vertical pipe runs
to the unit,
5 - In some localities, codes may require the installation of
a manual main shut-off valve and union (furnished by
the installer) external to the unit, The union must be of
the ground joint type,

A,CAUTION

A, IMPORTANT
Gas Supply
1 - This unit is shipped standard for left or right side installation of gas piping (or top entry in horizontal applications). Connect the gas supply to the piping assembly.

NOTE - Install a 1/8 inch NPT plugged tap in the field piping
upstream of the gas supply connection to the unit. The tap
must be accessible for test gauge connection. See figure 19.

2 - When connecting the gas supply piping, consider factors such as length of run, number of fittings, and furnace rating to avoid excessive pressure drop. Table 9
lists recommended pipe sizes for typical applications.

NQ TE - If emergency shutoff is necessarj4 shut off the main
manual gas valve and disconnect main power to the furnace. The installer should properly label these devices.

TABLE 9
Gas Pipe Capacity
Nominal
Iron Pipe
Size
inches
(ram)
3/8

- ft3/hr (m3/hr)

Internal
Diameter
inches
(mm)

10
(3.048)

20
(6.096)

30
(9.144)

40
(12.192)

50
(15.240)

60
(18.288)

70
(21.336)

80
(24.384)

90
(27.432)

100
(30.480)

.493
(12.522)

95
(2.69)

65
(1.84)

52
(1.47)

45
(1.27)

40
(1.13)

36
(1.02)

33
(.73)

(.88)

29
(.82)

27
(.76)

.622
(17.799)

175
(4.96)

120
(3.40)

97
(2.75)

82
(2.32)

66
(1.87)

61
(1.73)

(2.07)

(1.61)

5O
(1.42)

.824
(20.930)

360
(10.19)

250
(7.08)

2OO
(5.66)

170
(4.81)

151
(4.28)

138
(3.91)

125
(3.54)

118
(3.34)

(1.50)
11o

1.049
(26.645)

680
(919.25)

465
(13.17)

375
(10.62)

32O
(9.06)

285

26O
(7.36)

24O

(6.80)

22O
(6.23)

1.380
(35.052)

1400
(39.64)

950
(26.90)

77O
(21.80)

66O
(18.69)

(16.42)

(38.1)

1.610
(40.894)

2100
(59.46)

460
(41.34)

1180
(33.41)

990
(28.03)

9OO
(25.48)

2
(50.8)

2.067

3950

2750

2200

1900

1680

1520

1400

1300

1220

1150

(52.502)

(111.85)

(77.87)

(62.30)

(53.80)

(47.57)

(43.04)

(39.64)

(36.81)

(34.55)

(32.56)

2 -1/2
(63.5)

2.469
(67.713)

6300
(178.39)

4350
(123.17)

3520
(99.67)

2650
(75.04)

2400
(67.96)

2250
(63.71)

2050

(84.95

(58.05)

1950
(55.22)

1850
(52.38)

3
(76.2)

3.068
(77.927)

11000
(311.48)

7700
(218.03)

6250
(176.98)

4750
(134.50)

4300
(121.76)

3900
(110.43)

3700
(104.77)

3450
(97.69)

3250
(92.03)

(9.53)

1/2
(12.7)

3/4
(19.05)

1
(25.4)

1-1/4
(31.75)

1- 1/2

NOTE

- Capacity

given

Length of Pipe -feet(m)

in cubic feet

(In

3000
5300
(150.07)

of gas per hour and based

(8.07)
580

53O

(15.Ol)
81o
(22.94)

103
(2.92)

2O5

195

(5.80)

(5.52)
400

490
(13.87)

46O
(13.03)

430
(12.18)

(11.33)

75O
(21.24)

690
(19.54)

65O
(18.41)

62O
(17.56)

on O.60 specific gravity gas.

Page 20

(3.11)

Left Side Piping
(Standard)
MANUAL
MAIN SHUT-OFF

AUTOMATIC
GAS VALVE
(with manual
shut-off valve)

AUTOMATIC
GAS VALVE
(with manual

VALVE
(With 1/8 in. NPT
Plugged Tap Shown)

MANUAL
VALVE
(With 1/8 in. NPT
Shown)

shut-off valve /

JOINT
UNION
GROUND
JOINT
UNION

DRIP LEG

Right Side Piping
(Alternate)

FIELD
PROVIDED
AND INSTALLED

DRIP LEG

FIGURE 19
Leak Check
After gas piping is completed, carefully check all piping
connections (factory- and field-installed) for gas leaks, Use
a leak detecting solution or other preferred means.
NOTE - If emergency shutoff is necessa04 shut off the main
manual gas valve and disconnect the main power to the
furnace. The installer should properly label these devices.

ELECTROSTATIC

DISCHARGE (ESD)

Precautions and Procedures

&CAUTION

The furnace must be isolated from the gas supply system
by closing its individual manual shut-off valve during any
pressure testing of the gas supply system at pressures less
than or equal to 1/2 psig (3.48 kPa, 14 inches w.c.).

The unit is equipped with a field make-up box, The makeup box may be moved to the right side of the furnace to facilitate installation, If the make-up box is moved to the right
side, the excess wire must be pulled into the blower
compartment. Secure the excess wire to the existing harness to protect it from damage.

&IMPORTANT

INTERIOR MAKE-UP BOX INSTALLATION
MAKE-UP
BOX

MANUAL MAIN
SHUT-OFF VALVE
WILLNOTHOLD
NORMALTEST

ISOLATE
GAS VALVE
._.

PRESSURE

_i _

Right Side
FURNACE

_1]!
CAP /

FIGURE 20

FIGURE 21

Page 21

INTERIOR
MAKE-UP

NOTE - The G5OUH(X) furnace contains electronic
components that are polarity sensitive. Make sure
that the furnace is wired correctly and is properly
grounded.

BOX INSTALLATION
MAKE-UP

Left side

BOX

7 - One line voltage "EAC" terminal is provided on the furnace control board. Any electronic air cleaner rated up
to one amp can be connected to this terminal with the
neutral leg of the circuit being connected to any of the
"NEUTRAL" terminals. See figure 25 for control board
configuration. This terminal is energized when the
blower is operating,

8 - One line voltage "HUM" terminal is provided on the furnace control board, A humidifier rated up to one amp
can be connected to this terminal with the neutral leg
of the circuit being connected to any of the "NEUTRAL"
terminals. See figure 25 for control board configuration. This terminal is energized in the heating mode
whenever the combustion air inducer is operating.
9 - One 24 volt terminal "24V HUM" is provided on the furnace control board. A humidifier rated up to 0.5 amp
can be connected to this terminal with the common leg
of the circuit being connected to the "C" terminal d the
thermostat terminal block located on the control board.

FIGURE 22

Refer to figure 24 for field wiring and figure 26 for schematic
wiring diagram and troubleshooting.
1 - Select circuit protection and wire size according to the
unit nameplate. The power supply wiring must meet
Class I restrictions,

10-Install the room thermostat according to the instructions provided with the thermostat. See figure 23 for
thermostat designations. If the furnace is being
matched with a heat pump, refer to the FM21 installation instruction.
G50UH(X) and CONDENSING UNIT
THERMOSTAT DESIGNATIONS
(Refer to specific thermostat and outdoor unit.)

2 - Holes are on both sides of the furnace cabinet to facilitate wiring,
3 - Install a separate disconnect switch (protected by either fuse or circuit breaker) near the furnace so that
power can be turned off for servicing,

Thermostat

G50UH(X)
Furnace

PowER

4 - Before connecting the thermostat or the power wiring,
check to make sure the wires will be long enough for
servicing at a later date, Remove the blower access
panel to check the length of the wire,

5- Complete the wiring connections to the equipment.
Use the provided unit wiring diagram and the field wiring diagram shown in figure 24, Use 18-gauge wire or
larger that is suitable for Class II rating for thermostat
connections,
6 - Electrically ground the unit according to local codes or,
in the absence of local codes, according to the current
National Electric Code (ANSI/NFPA No, 70) for the
USA and current Canadian Electric Code part 1 (CSA
standard C22.1) for Canada. A green ground wire is
provided in the field make-up box,

Condensing
Unit

HsuN,T

FIGURE 23
Indoor Blower Speeds
1-

When the thermostat is set to "FAN ON," the indoor
blower will run continuously on the low speed when
there is no cooling or heating demand,

When the G50UH(X)is running in the heating mode,
the indoor blower will run on the heating speed.

When there is a cooling demand, the indoor blower will
run on the cooling speed,

Page 22

TYPICAL G50UH(X) FIELD WIRING DIAGRAM
{_V ACC
S{O
_IIIARYGAS

K43 EC(_
(IF USEO)
WARNINGELECTRIC
SHOCK HAZARD,CAN
CAUSE INJURY
OR DEATH.UNIT
MUST BE GROUNDED IN ACCORDANCE
WITH NATIONAL
AND LOCAL CODES,

IMPORTANTTO PREVENT
MOTOR BURNOUT,NEVER
THAN ONE MOTOR
LEAD TO ANY ONE
PARK TERMINALS
ARE
UNUSED
MOTOR LEADS
PARK TERMINAL.

C(_WBIJST
I(_NAIR
INN.ICERI_T_
{ALEImNATE}

L I-_=======_

CONNECT
MORE
CONNECTION.

UNPOWERED
TERMINALS.
MUST BE WIRED TO A

LIMIT
(_)
-'e

IF ANY WIRE IN THIS APPLIANCE
IS REPLACED, IT
MUST BE REPLACED
WITH WIRE OF LIKE SIZE,
RATING,INSULATION
THICKNESS
AND TERMINATION.
_

ALL

V_lTE-R(X)GERS
6A5 VALVE

orlo

FLAMEROLLOUT _

SWITCH

/:Zk FOR CORRECT
NUMBER
OF SECONDARY
LIMITS
USED,SEE
SECONDARY
LIMIT
SECTION
OF BLOWER
SPEED CHART.

SUPPLIED
COPPER

/Z_X 24V

HUM

CONNECT

-----

J,_
m_=l

_
CB8_ _
S2I
CIRCUIT
SECONE)ARY
BREAKER 6AS LIIIIT

I_ITI(_W
_
:O_TROL
_,
PIS_ _"
(_4:

P135

J,3_
F::F::I

ACC.IIRE.

CONDUCTORS

IS A

_A_ S47
_LLOm
_r_

I_NITERIR3$1

TRANSFORMER

ROOM

./6'kUSE

HONEYWELL
6AS VALVE

000
FLAI_
SENS_

FOR 650UH-56B-90
AND
G5OUH-4BC-135
ONLY.DO
NOT USE
RED (LOW SPEED)
MOTOR LEAD
FOR HEATING
SPEED.
LEAVE ON
PARK OR USE FOR CONTINUOUS
AIR
CIRCULATION(FAN).
FIELD

COIlBIJ_IT
ION AIR
S{gSWITCH
PROVIi_

I/4"

[E{)

_)@_)

OUICK

I I

TERMINAL

FIELD INSTALLED
FIELD INSTALLED

THIZRMOSTAT

ONLY.

FEMALE

CLASS II24V
LINE VOLTAGE

I I I

'1 _1,._
....
I

i'----

_' _

SECONDARY
6AS LIMIT

.,1'Ill,

"-------la

III

INOOOe
C4
BLOWER
MOTO_
CAPACITOR

J I

U.,T r
OUTB:_

---

....

FIGURE 24
INTEGRATED CONTROL BOARD
TEll\ IINAL DESIGNATIONS
COOL
H EAT
PARK
FAN
EAC
XFMR
LINE
HUM
5 Terminals
FS
24V HUM

1/4" FEMALE
QUICK
CONNECT

Blower- Cooling Speed (120MAC)
Blower - Heating Speed (120VAC)
Unused Blower (Not energized)
Continuous Low Blower Speed
Accessory Terminal (120VAC)
Transformer (120VAC)
Input (120VAC)
Heat Only Accessory (120VAC)
120 Volt Neutral
Flame Sensor
Heat Only Accessory

(24VAC)

SI DIP SWITCHES
HEAT OFF DELAY
l
2
SEC
OFF
OFF
60
OFF
ON
90 *
ON
OFF
120
ON
ON
180
COOL OFF DELAY

OFF

*Factory setting

FIGURE 25
Page 23

SEC
2 *
45

G5OUH(X)
120V ADO
OR

Schematic

SIS
COMBUSTION AIR
PROVING SWITCH

SlO

K43 ECON

Wiring Diagram
BLOWER SPEED CHART
FACTORY CONNECTED SPEED

PRIMARY GAS

(IF USED)

UNIT

LIMIT

COMBUSTION
INDUCER

AIR

"-L£P./

MOTOR

6V I

WHITE-RODGER9
/_

0[] 0

L_DTS

RED

........

2¢A-070
36A-070

fELLOW

RED

....

BROWN

3
4

BROWN
BROWN

RED
RED

....
....

YELLOt
YELLO_

4
€

{(RIGHT)
I(RISHT)

BROWN
fELLOW
fELLOW
fELLOW

RED
RED
RED
RED

....
....
....
....

t'ELLO£t
BROWN
BROWN
BROWN

44
44

_
I(R=eHT}
2
2

_
<

HX_BLOWER
- SPEED SELECTION
TAPS

BLACK

SPEED

BLACK

N/A

o o° .o...,ELLo,,

135
JO
135
155

GAS VALVE

BURNERS

PARK PARK

fELLOW

4BC60C-t
60D6DO°

HONEYWELL

GAS VALVE

FAN

L_
SECONDARY

MOTOR
SREE_
AVAIL,

24A-045

36B-090
_

(ALTERNATE)

GV f

COOL HEAT

TAPS

BROWN

YELLOW

RED

T.ERMOOTAT
.EAT
ANTICIPATION
SETTINES
Y_LI.QW

PLANE
NOLLDUT
\FLAME
I_NITER"_L_
SAT
SWITCH
SENSOR
JI59
FLAME ROLLOU'[
P159 E_

DOOR
INTERLOCI

SWITCH

TRANSFORMER
A92
BLO_R
IGNITION

COB c

$21

CIROOI
6REANEf

SECONDARY
GAS LIMIT

(EA-)

SI
ROOM THERMOSTAT

l i
l
[

TO PREVENT MOTOR DURMDUT,REVER CONNECT MORE
THAN ONE MOTOR LEAD TO ANY ONE CONNECTION.

(El)

JI35_

l_(_I
•--If-"
"

....

= I.
IL

_
Z_

IMPORTANTPARK TERMINALS ARE UNPOWEREDTERMINALS.

UNORED
MOTOR
LEAOO
MUST
6E
WIRED
TO
A

9ZI

I
I

IF ANY WIRE IN THIS APPLIANCE IS RSPLACED,IT
MUST 6E REPLACED WITH WIRE OF LIKE SIZE,
RATING,INSULATION
THICKNESS AND TERMINATION,

PIJS

P50

i®®.o®ol
.....
......

........

•

I
I
I
.-, ,,I
"1
.I
i= =
I
I

...........

SECONDARY
GAS LIMIT

I
II
, "=
I
I i
,,I
I
J I

..
Do
INDOOR
6LO_R
MOTOR

C4-

UNI<"r......
F-T-l, r ...........
.......
J

PARK

' _k

= ....

OUTDO(.
_

JACKPLU6 CHART
IJACK/PLUG-GURNER CONTROL

IJ.PIB9
IJACK/PLUD-IONITION
WARN INOELECTRIC SHOCK HAZARD,CAN CAUSE INJURY
OR DEATH.UNIT MUST BE GROUNDED IN ACCORDANCE
WITH NATIONAL AND LOCAL CODES.

CONTROLpIs6

IJ.P5B

CAPACITOR

F-------I

' I
" _

I (
_

i:&
_

FOR CORRECT NUM6ER OF SECONDARY
LIMITS USED,SEE SECONDARY LIMIT

A
/Ax

SECTION OF BLOWER SPEED CHART.
FOR G5DUH-3OO-90
AND
OODUH-4-BC-135 ONLY,DO NOT USE
RED (LOW SPEED) MOTOR LEAD
FOR HEATING SPEED. LEAVE ON
PARK

ALL

TERMINAL.

OR USE

FOR OONTINOOUS

CIRCULATION(FAN),

SI
._
_
LJ'-c>P_R
-TIIv
,_
II

AIR

_o'l

T_'II

ROOM THERMOSTAT
_
_..
\
.L
_
nN.-L,I
_') N
_
,_-"%'tI

/"_-_
]C ..I.
I'-_FANI
_0 C) r(3 I )-,'"1

_FIELOSH_LIEOAOO.WIRE.
_?_&ll..d
o-t_E___.YI
,_ USE
COPPER
CONDUCTORS
ONLY.
Y
'1I"°_L_ _oo%L /
A CONNECT
zAv,uMTERMINAL
ISA,,4-"FEMALE
OOICK
L I\ _
Lp L_ J

;

- 0O0R
,NTERL
_---CLASS
K ii VOLTARE
FIELD
,IRINO....
$51

L, _-0_

I-@

LINE

VOLTAGE

DENOTES OPTIONAL COMPONENTS

....

FIELD

INSTALLED

-_CK

.u.

24-_T

IZOVAC

'
K,€

-_K;

,_"

P98

PI59_/

R35

SPE_FED
CHART

Ilk-

"-./ "4/ "-./_

EQUIPMENT
WHITE

FIGURE 26

Page 24

"_L...--",P96

"y" _

I
S_. _I/

_'JSD '_"'_" '_r-

0v,

_,_ O=
_

YELLOW

sot

JI59,

,KS

,o;,.

PI59_

A9Z

J962 _ 4._-JISS

I"''T II

_._

VAC

I ._I/---_V

/'z, 9

I,Z_

3 - Turn off all electrical power to the unit,
4 - This furnace is equipped with an ignition device which
automatically lights the burners, Do not try to light the
burners by hand,

FOR YOUR SAFETY READ BEFORE LIGHTING

5 - Remove the upper access panel,

AWARNING

6 - Honeywell VR8205 Gas Valve with ON/OFF Switch
- Move gas valve switch to OFF, See figure 27.
Honeywell VR8205 Gas Valve with Control Knob Turn knob on gas valve clockwise 41_ to OFF. Do not
force, See figure 28,
White Rodgers 36G Gas Valve - Move gas valve
switch to OFF. See figure 29,
7 - Wait five minutes to clear out any gas. If you then smell
gas, STOP! Immediately call your gas supplier from a
neighbor's phone. Follow the gas supplier's instructions. If you do not smell gas go to next step.

AWARNING

Honeywell VR8205 Series Gas Valve
MANIFOLD
(With On/Off Switch)
PRESSURE

ACAUTION

MANIFOLD
PRESSURE
OUTLET

SCREW
(under cap)
DI

BEFORE LIGHTING smell all around the appliance area for
gas, Be sure to smell next to the floor because some gas is
heavier than air and will settle on the floor.
The gas valve on the G50UH(X) unit may be equipped with
either a gas control knob or gas control lever. Use only your
hand to push the lever or to tum the gas control knob. Never
use tools, If the knob will not turn or if the lever will not move
by hand, do not try to repair it. Call a qualified service technician, Force or attempted repair may result in a fire or explosion,
Placing the furnace

GAS VALVE ON/OFF SWITCH SHOWN IN OFF POSITION

FIGURE 27
Honeywell VR8205 Series Gas Valve
with Gas Control Knob
MANIFOLD
PRESSURE . _
ADJUSTMENT"'_'___,_,

MANIFOLD
_
PRESSURE
I h _'_'l_, OUTLET

into operation:

G50UH(X) units are equipped with a SureLight ® ignition
system. Do not attempt to manually light burners on these
furnaces, Each time the thermostat calls for heat, the
burners will automatically light. The ignitor does not get
hot when there is no call for heat on units with SureLight ®
ignition system,

SCREW

GAS VALVE SHOWN IN OFF POSITION

FIGURE 28
White Rodgers 36G Series Gas Valve

AWARNING

MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
(Undercover
SCOW)

Gas Valve Operation (Figures 27, 28 and 29)
1 - STOP! Read the safety information at the beginning of
this section,

PRESSURE
POST
GAS VALVE SHOWN IN OFF POSITION

FIGURE 29

2 - Set the thermostat to the lowest setting,

Page 25

Honeywell VR8205 Gas Valve with ON/OFF Switch
- Move gas valve switch to ON. See figure 27.
Honeywell VR8205 Gas Valve with Control Knob Turn knob on gas valve counterclockwise _
to ON,
Do not force. See figure 28,
White Rodgers 36G Gas Valve - Move gas valve
switch to ON, See figure 29,

9 - Replace the upper access panel,
10- Turn on all electrical power to to the unit,
11- Set the thermostat to desired setting,
NOTE - When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line,
12- If the appliance will not operate, follow the instructions
"Turning Off Gas to Unit" and call your service technician or gas supplier,

Gas Flow (Approximate)
1 - Operate unit at least 15 minutes before checking gas
flow. Determine the time in seconds for one revolutions of gas through the meter, A portable LP gas meter (17Y44) is available for LP applications,
2 - Compare the number of seconds and the gas meter
size in table 10 to determine the gas flow rate. Multiply
the gas flow rate by the heating value to determine the
unit input rate, If manifold pressure is correct and the
unit input rate is incorrect, check gas orifices for proper
size and restriction,
3 - Remove temporary gas meter if installed,
NOTE - To obtain accurate reading, shut off all other gas
appliances connected to meter,
TABLE 10

Turning Off Gas to Unit

Gas Flow Rate (Ft.'_/Hr.)
Gas Meter Size
Seconds for 1
1/2 cu ft Dial
1 cu ft Dial
Revolution
10
180
360
12
150
300
14
129
257
16
113
225
18
100
200
2O
90
180
22
82
164
24
75
150
26
69
138
28
64
129
3O
60
120
32
56
113
34
53
106
36
50
100
38
47
95
4O
45
90
42
43
86
44
41
82
46
39
78
48
38
75
5O
36
72
52
35
69
54
33
67
56
32
64
58
31
62
6O
30
60

1 - Set the thermostat to the lowest setting,
2 - Turn off all electrical power to the unit if service is to be
performed,
3 - Remove the upper access panel,
4 - Honeywell VR8205 Gas Valve with ON/OFF Switch
- Move gas valve switch to OFF, See figure 27.
Honeywell VR8205 Gas Valve with Control Knob Turn knob on gas valve clockwise clio to OFF, Do not
force, See figure 28,
White Rodgers 36G Gas Valve - Move gas valve
switch to OFF, See figure 29,
5 - Replace the upper access panel.
Heating Sequence

Of Operation

1 - When thermostat calls for heat, combustion air inducer
starts,
2 - Combustion air pressure switch proves combustion air
inducer operation. Switch is factory set and requires no
adjustment,
3 - After a 15 second prepurge, the hot surface ignitor energizes,
4-

After a 20 second ignitor warm-up period, the gas
valve solenoid opens,

5 - Gas is ignited, flame sensor proves the flame, and the
combustion process continues,
6 - If flame is not detected after first ignition trial, the ignition control will repeat steps 3 and 4 four more times
before locking out the gas valve ("WATCHGUARD"
flame failure mode), The ignition control will then automatically repeat steps 3, 4, 5, and 6 after 60 minutes,
7- To interrupt the 60-minute "WATCHGUARD" period,
move thermostat from "Heat" to "OFF" then back to
"Heat", Heating sequence then restarts at step 1.

Gas Pressure
1 - Check the gas line pressure with the unit firing at maximum rate. A minimum of 4.5 in, w.c. for natural gas or
11,0 in, w,c, for LP/propane gas should be maintained,
2- After the line pressure has been checked and adjusted, check the manifold pressure. A natural gas to
LP/propane gas changeover kit is required to convert
the unit, Manifold pressure for all units fueled by natu-

Page 26

ralgasatallaltitudesis3.5"w.c.Manifoldpressure
for
allunitsfueledbyL.R/propane
gasat allaltitudesis
10.0"w,c.Seefigures27, 28and29forthelocationof
themanifoldpressureadjustment
screws,

NOTE - In Canada, certification for installations at elevations over 4500 feet (1372 m) is the jurisdiction of local authorities.
Manifold pressure for all units fueled by natural gas at all
altitudes is 3.5" w,c, Manifold pressure for all units fueled
by L,R/propane gas at all altitudes is 10,0" w,c,
NOTE - A natural to L.R propane gas changeover kit is necessary to convert this un#. L.R conversion kit 25W20 is
used with all units installed at altitudes up to 7,500 feet. L.P.
conversion kit 25W21 is used with all units installed at altitudes from 7,501 to 10,000 feet above sea level. Refer to
the changeover kit installation instruction for the conversion procedure.
NOTE - Units fueled by natural gas and installed at altitudes of 7501-10,000 feet above sea level require installation of a high altitude orifice kit (59M17).
The combustion air pressure switches are factory-set and
require no adjustment, The existing unit pressure switch
must be replaced by pressure switch 56L32 for G50UH(X)
units installed at altitudes from 7,501 to 10,000 feet above
sea level,

Primary and Secondary

Limits

The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are located in the blower compartment, attached to the back side
of the blower. These limits are factory set and require no
adjustment.
Flame Rollout Switches

(Two)

These manually reset switches are located on (or inside of)
the burner box, If tripped, check for adequate combustion
air before resetting,
Pressure Switch
The pressure switch is located in the heating compartment
adjacent to the combustion air inducer. This switch checks
for proper combustion air inducer operation before allowing ignition trial, The switch is factory-set and requires no
adjustment.
Temperature

Rise

Place the unit into operation with a heating demand, After
supply and return air temperatures have stabilized, check
the temperature rise, If necessary, adjust the blower speed
to maintain the temperature rise within the range shown on

the unit nameplate, Increase the blower speed to decrease
the temperature, Decrease the blower speed to increase
the temperature rise, Failure to do adjust the temperature
rise may cause erratic limit operation,
Fan Control
Heating Mode -- The fan on delay of 45 seconds is not adjustable. The fan offdelay (amount of time that the blower
operates after the heat demand has been satisfied) may
be adjusted by setting $1 switches 1 and 2 located on the
SureLight ® control. The unit is shipped with a factory fan
off setting of 90 seconds, The fan off delay affects comfort and is adjustable to satisfy individual applications.
Adjust the fan off delay to achieve a supply air temperature between 90 ° and 110° F at the exact moment that the
blower is de-energized. Longer offdelay settings provide
lower return air temperatures; shorter settings provide
higher return air temperatures. See figure 25.
Cooling Mode --The cooling mode fan off delay (amount
of time that the blower operates after the cooling demand
has been satisfied) may be adjusted by setting $1 switch
3 located on the SureLight ® control, In the off position,
the cooling fan off delay is 2 seconds. In the on position,
the cooling fan off delay is 45 seconds, See figure 25,
Thermostat Heat Anticipation
Set the heat anticipator setting (if adjustable) according to
the amp draw listed on the wiring diagram that is attached
to the unit.
Electrical
1 - Check all wiring for loose connections,
2 - Check for the correct voltage at the furnace (furnace
operating).
3 - Check amp-draw on the blower motor.
Motor Nameplate
Actual
NOTE - Do not secure the electrical conduit directly to the
air ducts or structure.
Blower Speeds
NOTE - CFM readings are taken external to unit with a dry
evaporator coil and without accessories.
1 - Turn off electrical power to furnace,
2 - Remove blower access panel.
3 - Disconnect existing speed tap at control board speed
terminal.
NOTE - Termination of any unused motor leads must be
insulated.
4 - Refer to blower speed selection chart on unit wiring diagram for desired heating or cooling speed.
5- Connect selected speed tap at control board speed
terminal.
6 - Resecure blower access panel.
7 - Turn on electrical power to furnace,
Electronic Ignition
The SureLight @integrated control has an added feature of
an internal Watchguard control, The feature serves as an
automatic reset device for ignition control lockout caused
by ignition failure, After one hour of continuous thermostat
demand for heat, the Watchguard will break and remake
thermostat demand to the furnace and automatically reset
the control to begin the ignition sequence,

Page 27

FlueAnd Chimney
1 - Checkfluepipe,chimneyandallconnections
fortightnessandtomakesurethereisnoblockage,
2 - Checkunitforproperdraft,
3 - Ispressureswitchclosed?Obstructed
fluewillcause
unittoshutoffatpressure
switch,Checkflueandoutlet
forblockages.
4- Resetmanualflamerolloutswitcheson burnerbox
cover.
FailureToOperate
If theunitfailstooperate,checkthefollowing:
1 - Isthethermostat
callingforheat?
2 - Areaccesspanelssecurelyinplace?
3 - Isthemaindisconnect
switchclosed?
4 - Istherea blownfuse?
5 - Isthefilterdirtyorplugged?
Dirtyorpluggedfilterswill
causethelimitcontroltoshuttheunitoff.
6 - Isgasturnedon atthemeter?
7 - Isthemanualmainshut-offvalveopen?
8 - Istheinternalmanualshut-offvalveopen?
9 - Istheunitignition
systeminlockout?Iftheunitlocksout
again,calltheservicetechnician
toinspecttheunitfor
blockages.

Filters
All G50UH(X) filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure that the furnace operates properly. Replacement filters must be rated for high velocity airflow. Table 1 lists recommended filter sizes.
Flue And Chimney
Check the flue pipe, chimney and all connections for tightness and to make sure there is no blockage,
Electrical
1 - Check all wiring for loose connections.
2 - Check for the correct voltage at the furnace (furnace
operating),
3 - Check amp-draw on the blower motor.
Motor Nameplate
Actual
Cleaning

the Heat Exchanger

and Burners

NOTE - Use papers or protective covering in front of the furnace during cleaning.
Cleaning the heat exchanger requires a steel spring
"snake," a reversible drill and a vacuum cleaner, The steel
spring snake may be constructed by purchasing a 4 ft. long
by 1/4 inch diameter steel wire cable and a 1/4 inch diameter wire brush, These items are available at a hardware
store. Insert wire end of brush into the open end of the
spring cable. Crimp the cable around the brush so that the
brush is secured and will not come off during cleaning, Attach the other end of the cable to the reversible drill to complete the tool for cleaning the heat exchanger.

,AWARNING

1 - Turn off both electrical and gas power supplies to furnace.
2 - Remove flue pipe and top cap from the unit. Label the
pressure switch wires, then disconnect them.
3 - Remove the four screws that secure the combustion air
inducer. Carefully remove the combustion air inducer to
avoid damaging blower gasket. If gasket is damaged, it
must be replaced to prevent leakage. See figure 30.

A, CAUTION

G50UH(X) BURNER & HEAT
EXCHANGER REMOVAL
At the beginning of each heating season, a qualified technician should check the system as follows:
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.

H EAT

BURNER BOX ASSEMBLY

,&WARNING

FIGURE 30

Page 28

4 - Removethecollectorboxlocatedbehindthecombustionairinducer.Becarefulwiththecollectorboxgasket.If thegasketis damaged,it mustbereplacedto
preventleakage,
5 - Labelthewiresfromgasvalveandrolloutswitches,
thendisconnect
them.
6 - Disconnect
gassupplypiping.Remove
fourscrewssecuringthe burnermanifoldassemblytothevestibule
panelandremovetheassemblyfromtheunit,
NOx INSERTS
(X models only)

11- Remove the cable from the heat exchanger. Use a vacuum cleaner to remove debris knocked loose during
cleaning.
12- Attach the exhaust end (positive pressure) of the vacuum cleaner to the top of the heat exchanger section,
Any loose debris will be forced to the bottom of the heat
exchanger section, Vacuum debris from bottom openings.
13- Replace collector box and combustion air inducer.
Check gaskets for damage. Damaged gaskets must be
replaced to avoid heat exchanger leaks. Replace all
screws to the collector box and combustion air inducer.
Failure to replace all screws may cause leaks,
14- To clean the burner, run a vacuum cleaner with a soft
brush attachment over the face of burners. Visually inspect inside the burners and crossovers for any blockage
caused by foreign matter. Remove any blockage,
15- NOx Units - Reattach the NOx inserts to the corbels at
the entrance to each heat exchanger opening, See figure 31,

16- Replace burner/manifold
panel,

assembly onto the vestibule

17- Reconnect wires to pressure switch, roll-out switches,
gas valve and combustion air inducer. Refer to unit wiring diagram,
18- Reconnect vent pipe to combustion air inducer outlet,
19- Reconnect gas supply piping,
20- Turn on power and gas supply to unit,

FIGURE 31

21- Set thermostat and check for proper operation,
7 - NOx units only- Remove the three screws that attach
the NOx insert to the corbel at the entrance to each
heat exchanger section, Carefully remove the NOx insert from each section, See figure 31.

22- Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means,

8 - Insert the brush end of cable snake into the top of one
of the heat exchanger openings, Do not force the
cable into the heat exchanger. Insert the cable and
operate the drill on slow speed. Move the cable in and
out of the heat exchanger section three or four times or
until sufficient cleaning is accomplished. Reverse drill
and slowly work the cable out of opening,
9- Repeat procedure for each heat exchanger section.
10- After each of the top heat exchanger sections has been
cleaned, insert the brush end of the cable snake into
the bottom openings of each of the heat exchanger
sections and clean as described in step 8,

Ak CAUTION

23- Ira leak is detected,
repair leak,

shut gas and electricity

offand

24- Repeat steps 23 and 24 until no leaks are detected.
25- Replace front access panel.

Page 29

ThefollowingrepairpartsareavailablethroughLennoxdealers.Whenorderingparts,includethecomplete
furnacemodel
numberlistedontheCSAInternational
nameplate
--Example:
G50UH(X)-24A-045-8,
CabinetParts
HeatingParts
Upperaccesspanel
FlameSensor
Blowerpanel
Heatexchanger
assembly
Topcap
Gasmanifold
ControlPanelParts
Combustion
airinducer
Transformer
Gasvalve
SureLight
®ignitionboard
Mainburnercluster
Doorinterlockswitch
Mainburnerorifices
Circuitbreaker
Pressure
switch
BlowerParts
Ignitor
Blowerwheel
Primarylimitcontrol
Motor
Flamerolloutswitch
Motormountingframe
Secondary
limit(notusedon24A-45-1)
Motorcapacitor
Blowerhousingcutoffplate

DIAGNOSTIC

CODES

Make sure to Identify LED'S Correctly.
Refer to Installation Instructions for control board layout,
DSl
(Red or Green)

DS2
(Green)

DESCRIPTION

SIMULTANEOUS
SLOW FLASH

Power on -- Normal operation.
Also signaled during cooling and continuous fan.

SIMULTANEOUS
FAST FLASH

Normal operation -- Signaled when heating demand initiated at thermostat.

SLOW FLASH

Primary or secondary limit switch open. Limit must close within 3 minutes or unit
goes into 1-hour Watchguard.

OFF

SLOW FLASH

Pressure switch open;
OR: Blocked inlet/exhaust vent;
OR: Condensate line blocked;
OR: Pressure switch closed prior to activation of combustion air inducer.

ALTERNATING
SLOW FLASH

Watchguard -- Burners failed to ignite, limit open longer than 3 minutes, or flame
sense lost 5 times in one heating cycle.

SLOW FLASH

OFF

SLOW FLASH

OFF

FAST FLASH

SLOW FLASH

Main power polarity reversed. Switch line and neutral. Improper main ground.

SLOW FLASH

FAST FLASH

Low flame signal. Check flame sensor.

ALTERNATING
FAST FLASH

The following conditions are sensed during the ignitor warm-up period only:
1) Improper main ground;
2) Broken ignitor; OR: Open ignitor circuit;
3) Line voltage below 75 volts.

Flame sensed without gas valve energized.
Rollout switch open.
Circuit board failure or control wired incorrectly. Check 24-volt and 115-volt
connections to board.

NOTE - Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second).
Drop out flame sense current = 0.15 - 0.24 microAmps.

Page 30

SURELIGHT
®CONTROL
HEATING SEQUENCE OF OPERATION
NORMAL HEATING MODE

POWER ON

_'
CONTROL SELF-CHECK

ABNORMAL

]

GAS VALVE OFF. COMBUSTION

I,_
_
; NO |
|

aYES _

OKAY'_
"

,sPOLARITY
REVERSED? _1
i- I

I
LED#1 AND LED#2
ALTERNATING FAST
FLASH, SIGNAL
NO
HOLDS UNTIL UNIT IS| ._--I
PROPERLY
GROUNDi_I

-_I

J_
•
ISTHERE
PROPER GROUND?

/I
/
1'

YESI

I NO I

MAIN POWER OFF)

POLARITY REVERSED.
LED #1 -- FAST FLASH
LED #2 -- SLOW FLASH

I_-----I
'

II _I LED#1
AND
LED#2
ALTERNATING
FASTI

•
SWITCH

TURNING
_

YES
/
ROLLOUT

LED
#1ON
LED #2 ON

I (R__

ISVOLTAGE
ABOVE 75 VOLTS?

CLOSED?

I'--ml FLASH. SIGNAL HOLDS UNTIL VOLTAGE
I_ I
RISES ABOVE 75 VOLTS.

YESi

in,--

|
'_
GAS VALVE

I1"I"1
_1
I

DE-ENERGIZED?

LED #1 -- SLOW FLASH
NORMAL
OPERATION:
LED #2 -- SLOW
FLASH

ISEQUENCE

YES
IS COMBUSTION
PRESSURE

AIR

SWITCH OPEN?

YES _1
I

IS
COMBUSTION
INDUCER ENERGIZED?
(HUM
TERMINAL AIR
IS ENERGIZED
WITH C.A.I.)

YES
|

15-SECOND COMBUSTION AIR INDUCER PREPURGE
N T ATED BY CLOSED PRESSURE SW TCH.

I
I
m

YES
CONTINUED

COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 OFF
LED #2 SLOW FLASH
VALVE
OFF.
(Sequence GAS
holds
until pressure
switch
closes or thermostat resets control,)

HAS
SWITCH
COMBUSTION
CLOSED INAIR
2.5 PRESSURE
MINUTES?

Page 31

HOLDS UNTIL ROLLOUT SWITCH CLOSES.

THERMOSTAT CALLS FOR HEAT:
LED #1 -- FAST FLASH
LED #2 -- FAST FLASH

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 -- ON. LED #2 -- SLOW FLASH,

YEs_

ON.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER DELAY OFF.

AIR INDUCER

INDOOR BLOWER ON.
LED #1 ALTERNATING FAST FLASH
LED#2 ALTERNATING FAST FLASH
CHECK FOR BROKEN IGNITOR OR

-I

HEATING MODE

PRESSURE SWITCH IS IN WATCHGUARD MODE.
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY,
LED #1 -- OFF. LED #2 -- SLOW FLASH,
IS 5-MINUTE RESET PERIOD COMPLETE?

NORMAL HEATING MODE

ABNORMAL

15-SECOND
COMBUSTION
INDUCERSW
PREPURGE
N T ATED
BY CLOSED AIR
PRESSURE
TCH.
YES
I

HEATING MODE

-_O

YES_

. NO I

YES_t

INOI
I--=-_l

S VOLTAGE ABOVE 75 VOLTS?

IGNITOR WARM-UP -- 20 SECONDS.
YES

_IIW

GAS VALVE OPENS, IGNITOR ENERGIZED
4-SECOND
UP TO
TRIAL
4 SECONDS,
FOR IGNITION.

ISTHERE A PROPER
GROUND?
ISIGNITOR INTACT AND CONNECTED?I_"I

FOR

INDOOR BLOWER OFF.
HAS CONTROL FA LED TO SENSE FLAME FOR

YES
I

FLAME STABILIZATION

PERIOD.

SEQUENCE

INDOOR BLOWER
ON DELAY BEGINS
(45 seconds,)
YES

PRIMARY
SWITCHES
AND SECONDARY
CLOSED?

|
I
YES
I
I
I,.__
I

HAS
CONTROL
RESET
,GN,T,ON_,Z_._I

FLAME SIGNAL ABOVE 0.31 MICROAMPS?
YES

COMBUSTION
AIR INDUCER
OFF.
GAS VALVE
OFF. COMBUSTION
AIR INDUCER
ON.
INDOOR
BLOWER OFF
WITH
IGNITION
WATCHGUARD
MODE.
GASDELAY
VALVE OFF.
LED 1 ALT. SLOW FLASH LED 2 ALT SLOW FLASH
IS 60-MINUTE RESET PERIOD COMPLETE?

I
I_

FLAME PRESENT?

FLAME RECTIFICATION CURRENT
CHECK. CAN FLAME BE PROVEN WITHIN
4 SECONDS AFTER GAS VALVE OPENS?
( > 0.24 microamps)

YES

FIVE CONSECUTIVE TRIES DURING A SINGLE
HEAT DEMAND?

4 SECONDS

YES

LEDS SIGNAL
ALTERNATING
FAST FLASH

LIMIT

I
F-

FOUR TIMES?

LOW FLAME SIGNAL
(Does not affect operation of control)
LED #1 -- SLOW FLASH
LED #2 -- FAST FLASH

GAS VALVE DE-ENERGIZED
COMBUSTION AIR INDUCER
DE-ENERGIZED.INDOOR
BLOWER
ON UNTIL SWITCH CLOSES.LED #1
-- SLOW FLASH, LED #2 -- ON.
IS LIMIT SWITCH CLOSED?

NO
Ii

YES
l
LIMIT SWITCH WATCHGUARD MODE. GAS
VALVE OFF. COMB. AIR
INDUCER OFF. INDOOR
BLOWER OFF WITH
DELAY, LED#I-SLOW
FLASH LED#2 - ON. IS
60MINUTE RESET
PERIOD COMPLETE?

YES
HAS PRIMARY/SECONDARY
LIMIT
RESET (CLOSED) WITHIN 3
MINUTES?

YES

GAS VALVE POWER OFR
COMBUSTION AIR INDUCER POWER OFF.
INDOOR BLOWER OFF WITH DELAY
LED #1 -- ON. LED #2 -- SLOW FLASH,
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET

NO
I

ROLLOUT SWITCH CLOSED?

YES

÷1

COMBUSTION AIR PRESSURE
SWITCH CLOSED?
YES

THERMOSTAT

YES

DEMAND SATISFIED.

YES

LED #1 & #2 SIMULTANEOUS

SLOW FLASHES.

YES _
COMB. AIR INDUCER CONTINUES 5-SECOND
POST PURGE AFTER T'STAT DEMAND IS SATISFIED,
INDOOR AIR BLOWER COMPLETES SELECTED "OFF"
DELAY BEFORE SHUTTING OFF.

COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF WITH DELAY
LED #1
-- OFF.
LED
#2 -- SLOW FLASH,
I
GAS
VALVE
DE-ENERGIZED
HAS CAB SWITCH CLOSED IN 2.5 MINUTES?

NO_
I

Page 32

5-MINUTE
PRESSUREMODE,
SWITCH
WATCHGUARD

YES

]

SURELIGHT®CONTROL
COOLING
SEQUENCE
OF OPERATION
NORMALCOOLING
I

MODE

POWER ON

ABNORMALCOOLING

MODE

IGNITION
CONTROL
MA,
NPOWER
ON

I
GAS VALVE OFF, COMBUSTION AIR INDUCER OFR
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
INTERRUPT MAIN POWER TO RESET CONTROL,

I CO.T O S O,A .OS ,OO. OK
IS CONTROL

OPERATING

NORMALLY?

Y sJ
I

,sPOLARITY
REVERSED?
_
LED_IFAST
FLASH
LED_2
SLOW
FLASH
I
/

LED#1 AND LED#2

ALTERNATING FAST
I NO _
__
FLASH. SIGNAL
_
IS THERE
I HOLDS UNTIL UNIT IS I_1
PROPER GROUND?
[PROPERLY

GROUND.

I YESJ
I_IABOVE

I ROLLOUT ISSWITCH
CONTINUOUSLY.
ROLLOUTMONITORED
SWITCH CLOSED?

YESl

_
I_--I

t
I CHECK TO ENSURE
GAS
VALVE
IS DE-ENERGIZED.
S GAS
VALVE
OFF?

I LED:SLOW
THROUGHOUT
FLASH RATEREMAINS
COOLING CYCLE.
UNCHANGED

THERMOSTAT

CALLS FOR COOLING.

COMPRESSOR CONTACTOR IS ENERGIZED,
INDOOR BLOWER ON COOL SPEED AND EAC
TERM NAL S ENERG ZED AFTER 2-SECOND

I_'

LED#1 AND LED#2 ALTERNATING FAST
FLASH. SIGNAL HOLDS UNTIL VOLTAGE
RISES ABOVE 75 VOLTS.

I
• NO

Is VOLTAGE
75 VOLTS?

THERMOSTAT

COMPRESSOR

DELAY,

OPENS.

OFF.

SYSTEM FAN AND EAC TERM, OFF
WITH 2 OR 45-SECOND DELAY,

Page 33

GAS VALVE OFF COMBUSTION

AIR INDUCER

OFF

INDOOR
WITHFAILURE
NORMAL ATDELAY.
SIGNAL BLOWER
CIRCUIT OFF
BOARD
LED,

ISEQUENCEHOLDS

UNTIL ROLLOUT SWITCH CLOSES.

SURELIGHT ® CONTROL
CONTINUOUS FAN SEQUENCE OF OPERATION

LED: SLOW FLASH RATE REMAINS
UNCHANGED THROUGHOUT SEQUENCE.

MANUAL FAN SELECTION

MADE AT THERMOSTAT.

CONTROL (G) ENERGIZES INDOOR BLOWER AT
FAN SPEED. EAC TERM. IS ENERGIZED.
/

THERMOSTAT

CALLS FOR HEAT (W).

YEs

NO
THERMOSTAT

I--l't
/

HUM TERM. ENERGIZES
WITH COMB. AIR INDUCER.

CALLS FOR COOLING.
AFTER NORMAL DELAY.

_YES
INDOOR BLOWER SWITCHES

TO COOL SPEED.

I
THERMOSTAT

AND HUM OPENS.
TERMINALCOMBUSTION
ARE DE-ENERGIZED.
THERMOSTAT
AIR INDUCER

OPENS.

AFTER DELAY HEAT SPEED DE-ENERGIZED.
J INDOOR BLOWER SELECTED TIME OFF DELAY BEGINS. I
(bower rema ns energ zed dur ng cont nuous fan mode).

INDOOR BLOWER SWITCHES TO FAN
SPEED, EAC TERM, REMAINS ENERGIZED,

Page 34

JobName

JobNo.

Date

JobLocation

City

State

Installer

City

State

UnitModelNo.

Technician

SerialNo.
Heating Section

[]

Electrical
Connections
Tight?

Blower Motor H.P.

SupplyVoltage
BlowerMotorAmps

[]

Gas Piping Connections
Tight & Leak-Tested?

[]

FuelType:NaturalGas?

LP/Propane Gas?

[]

FurnaceBtuInput
Line Pressure
Regulator Pressure

w.c. _ Nat,:

w.c. - LP/Propane

Flue Connections Tight?

[]

Proper Draft?

Combustion Gas Tested?

[] 002 [] co

Fan Control Setting
(45 Seconds Fixed On)

[]

Temperature Rise

Fan Control Off Setting
Filter Clean & Secure?

[]

Vent Clear?

[]

Thermostat
Calibrated?

[]

Heat Anticipator Properly Set?

[]

Page 35

Level? []

Source Exif Data:

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File Type Extension             : pdf
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PDF Version                     : 1.2
Linearized                      : No
Page Count                      : 35
Page Layout                     : SinglePage
Page Mode                       : UseNone
Producer                        : Goby Monitor Application version 4, 0, 0, 13
Create Date                     : Mon Jun 30 04:40:06 2008
Author                          : 
Title                           : 
Subject                         :

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Lennox International Inc G50Uh 24A 045 Users Manual

LENNOX Furnace/Heater, Gas Manual L0806179 LENNOX Furnace/Heater, Gas Owner's Manual, LENNOX Furnace/Heater, Gas installation guides

G50UH-48C-110 to the manual 74bf3324-cf3b-4d2b-aaf5-4cd643369a3c

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