LENNOX Furnace/Heater, Gas Manual L0806234

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

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INSTALLATION
INSTRUCTIONS

E Wvm)
®
_ 2007 Lennox Industries Inc.
Dallas, Texas, USA

G71MPP SERIES UNITS
GAS UNITS
50&334M

Technical

03/2008

J LJ _,Publications

Litho U.S.A.

Unit Dimensions ...............................
G71MPP Parts Arrangement .....................
Shipping and Packing List .......................
Safety Information ..............................
General .......................................
Installation - Setting Equipment ..................
Filters ........................................
Duct System ..................................
Pipe & Fittings Specifications ...................
Vent Pipe Sizing Worksheet ....................
Vent Piping Guidelines .........................
Joint Cementing Procedure .....................
Venting Practices .............................
Gas Piping ...................................
Electrical .....................................
Integrated Control .............................
Blower Motor Performance .....................
Unit Start-Up .................................
Gas Pressure Measurement ....................
High Altitude Information .......................
Other Unit Adjustments ........................
Heating Sequence of Operation .................
Service ......................................
Ignition Control Diagnostic Codes ...............
Troubleshooting ...............................
Repair Parts List ..............................
Start-Up & Performance Check List ..............

RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE

2
3
4
4
6
6
12
13
13
14
15
16
17
25
27
33
40
51
52 ,
53
54
55
57
59
60
66
66

AWARNING

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

• 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.

03/08

IIIHIININIIIIIIIIIIIIIIIIIIIIIIIIIIII

GAS:

505,334M
Page 1

IIIIIINIIIIIIIIIIIIIIIHIIII

1 NOTE - 60C and 60D size units that require air volumes over
1800 cfm (850 L/s) must have one of the following:
a. 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.
b. Single side return air with optional RAB Return Air Base.
c. Bottom return air.
d. Return air from both sides.
e. Bottom and one side return air.
See Blower Performance

Tables for additional

SUPPLY AIR
OPENING

information.

Optional External Side Return Air Filter Kit (Upflow Only) is not
for use with the optional RAB Return Air Base.

23-3/4 (603)
2 OPTIONAL

,,_

EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)

A -_

25 (635)
TOP VIEW

28 -1/2

,_v-----

B -_D,.

9-9/16

(14)

(724)

1.9_

5-1/2
(140) t

r_
....

6-1/2

11-5/8
(295) Right
9-3/4 (248)
Left

2OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)

(1_5)
4-1/8
(103)

6-3/4
(171)

COMBUSTION AIR INTAKE
_
(Either Side)

( Iy \ / EXHAUST
AIROUTLET
9- _/_

_11
_ y\

1-3/4 (45) Right
3-9/16 (91) Left -I_

40
(1016)

9/16
'q'- (14)

19-7/16_

L
°Oo_

_
_

_p_,ql__

(Either Side)

GAsP,P,NG,NLET
(Either Side)
\ .r_ CONDENSATE
TRAPCONNECTION
(Either Side)
ELECTRICAL INLET
(Either side )

(64)
A 2-1/2 .__
18-3/4 (476)

04I
(102

3/4 (19)

--J_-

•

(584)
1 OPTIONAL

(Either Side)

i
14

(3.._6)

1-15/16 (49)

5/8(16)
314(19)

1Bottom Return
Air Opening
FRONT VIEW

4-1/4
(108)

A
Model No.

L
Up-Flow
Only
I RETURN
CUTOUT

AIR FLOW

Jl.--c

-23

1 Bottom Return
Air Opening
SIDE VIEW

in.

G71MPP-36B-070

17-1/2

446

16-3/8

416

406

G71MPP-36C-090
G71MPP-60C-090
G71MPP-60C-110

533

19-7/8

454

19-1/2

495

G71MPP-60D-135

24-1/2

622

23-3/8

546

584

Page 2

BAGASSEMBLIES
(shippinglocation)

HEATEXCHANGER
BURNERBOXASSEMBLY

VARIABLE CAPACITY
GAS VALVE

WARM HEADER
(COLLECTOR BOX)
CONDENSER COIL
PRESSURE SWITCH
ASSEMBLY WITH
PRESSURE
CONDITIONING
DEVICE

COMBUSTION AIR
PRESSURE
SWITCHES

COLD HEADER
(COLLECTOR BOX)

VARIABLE SPEED
COMBUSTION AIRINDUCER

SHIPPING BLOCK
(-135unitsonly)

BURNER ACCESS PANEL

BLOWER ACCESS PANEL
VARIABLE SPEED
BLOWER MOTOR

SIGHT GLASS

TRANSFORMER
FIGURE 1

Page 3

INTEGRATED
CONTROL

DANGER
TheG71MPPgasfurnaceisequippedwitha variable-capacity,variable-speed
integrated
control.Thiscontrolensurescompatibility
withLennox'HarmonyIII'" zonecontrol system,as well as a thermostatwhich provides
humiditycontrol.EachG71MPP
is shipped
readyforinstallationintheupflow,downflow,
horizontal
leftairdischarge
or horizontal
rightairdischargeposition.
Thefurnaceis equippedforinstallation
in naturalgasapplications.
A conversion
kit(ordered
separately)
is required
forusein propane/LP
gasapplications.
The G71MPP can be installed only as a Direct Vent gas
central furnace.

&WARNING

NOTE- In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors.
See figure 2 for applications including roof termination.
DIRECT

VENT

INSTALLATION
EXHAUST

OUTLET

-&CAUTION

COMBUSTION
AIR INTAKE
OUTSIDE
OF
HOUSE

Use only the type of gas approved for use with this furnace.
Refer to unit nameplate.
G71MPP units are CSA International certified to ANSI
Z21.47 and CSA 2.3 standards.

FIGURE 2

Package 1 of 1 contains
1 - Assembled G71MPP unit
1 - Bag assembly containing the following:
3 - Screws
3 - Wire nuts
1 - Snap bushing
1 - Snap plug
1 - Wire tie
1 - Condensate trap
1 - Condensate trap cap
2 -2" diameter vent / intake plugs
1 -3" diameter cabinet plug (intake)
NOTE- G 71MPP-60C-110 units also include a 2" diameter
PVC street elbow, which is shipped on the blower deck in
the heating compartment. G71MPP-60D-135 units are
shipped with a 3" to 2" PVC reducing elbow.
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
The following items may also be ordered separately:
1- Thermostat
1 - Propane/LP changeover kit

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 (ANSl-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.
This furnace is CSA International certified for installation
clearances to combustible material as listed on the unit
nameplate and in the tables in figures 4, 9 and 13. Accessibility and service clearances must take precedence over
fire protection clearances.
NOTE- For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.
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
Page 4

garage,hangar,or otherbuildingthathasa hazardous
atmosphere,
thefurnacemustbeinstalled
according
torecommended
goodpracticerequirements
andcurrentNationalFuelGasCodeor CSAB149standard.

The G71MPP furnace may be installed in alcoves, closets,
attics, basements, garages, and utility rooms.

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.

Never use an open flame to test for gas leaks. Check all
connections using a commercially available soap solution
made specifically for leak detection.

This G71MPP furnace may be used as a high-static unit
heater. The G71MPP may also be installed in an aircraft
hangar in accordance with the Standard for Aircraft Han-

Lennox does not recommend the use of G71MPP units as

gars (ANSI/NFPA No. 408-1990).
Installation in parking structures must be in accordance
with the Standard for Parking Structures (ANSI/NFPA No.
88A-1991 ). Installation in repair garages must be in accordance with the Standard for Repair Garages (ANSI/NFPA
No. 88B-1991).
This G71MPP furnace must be installed so that its electrical components are protected from water.
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.
When installed, this furnace must be electrically grounded
according to local codes. In addition, in the United States,
installation must conform with the current National Electric
Code, ANSI/NFPA
(ANSI/NFPA
dress:

No. 70. The National Electric Code

No. 70) is available from the following ad-

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

a 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.
G71MPP units may be used for heating of buildings or
structures under construction, if the following conditions
are met:
• The vent system must be permanently
these installation instructions.

installed per

• A room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
aflowed.
• 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 inputrate and temperature rise mustbe setperthe
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.
• The furnace heat exchanger, components, duct system, air filters and evaporator coils must be thoroughly
cleaned following final construction clean-up.

National Fire Protection Association
1 Battery March Park
Quincy, MA 02269
In Canada, all electrical wiring and grounding for the unit
must be installed according to the current regulations of the
Canadian Electrical Code Part I (CSA Standard C22.1)
and/or local codes.

• 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 licensedplumber or gas fitter only.

A CAUTION

• 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.

Page 5

In addition to the requirements outlined previously, the following general recommendations must be considered
when installing a G71MPP furnace:
• Place the furnace as close to the center of the air distribution system as possible. The furnace should also be
located close to the chimney or vent termination point.
• When the furnace is installed in an attic or other insu-

,-& WARNING

lated space, keep insulation away from the furnace.
• When the furnace is installed in an unconditioned
space, consider provisions required to prevent freezing
of condensate drain system.

,&,CAUTION

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

-&WARNING

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,
condensate trap and drain connections, and installation
and service clearances [24 inches (610 mm) at unit front].
The unit must be level from side to side. The unit may be
tilted slightly (maximum 1/2 in.) from back to front to aid in
the draining of the heat exchanger. See figure 3.

SETTING EQUIPMENT
UPFLOW APPLICATION

DOWNFLOW APPLICATION
UNIT MUST BE LEVEL SIDE-TO-SIDE

IN ALL APPLICATIONS.
AIR FLOW

HORIZONTAL APPLICATION

t1"
AIR FLOW
m

FRONT VIEW

UNIT
FRONT

UNIT
FRONT
1/2"
I rflax,

EN D VIEW

112"
max.

SIDE VIEW

1/2"
rflax.

UNIT MAY BE TILTED SLIGHTLY
TO AID IN THE DRAINING

(MAX. 1/2") FROM BACK TO FRONT
OF THE HEAT EXCHANGER.

FIGURE 3
Page 6

SIDE VIEW

NOTE - G71MPP-36B and -36C units with 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.

Installation

Top

Left Side

NOTE - G 71MPP-60D-135 units are equipped with a shipping pad under the blower housing. Remove the shipping
pad prior to operation.
Allow for clearances to combustible materials as indicated
on the unit nameplate, Minimum clearances for closet or alcove installations are shown in figures 4, 9 and 13,

WARNING

Clearances

Right Side

Bottom (Floor)
Top/Plenum

1 in. (25 ram)

*Front

Back

Sides

0-_

Vent

Floor

*Front clearance in alcove installation must be 24 in. (610 ram).
Maintain a minimum of 24 in. (610 ram) for front service access.
tAllow proper clearances to accommodate condensate trap and
vent pipe installation.
SFor installations on a combustible floor, do not install the furnace directly on carpeting, tile or other combustible materials other than wood flooring.

WARNING

FIGURE 4
Return Air -- Upflow Units
Return air can be brought in through the bottom or either
side of the furnace installed in an upfiow application. If the
furnace is installed on a platform with bottom return, make
an airtight seal between the bottom of the furnace and the
platform to ensure that the furnace operates properly and
safely. The furnace is equipped with a removable bottom
panel to facilitate installation,
Markings are provided on both sides of the furnace cabinet
for installations that require side return air. Cut the furnace
cabinet at the maximum dimensions shown on page 2,

Upflow

NOTE - When air volumes over 1800 cfm (850 L/s) are
required with 60C or 60D models in an upflow application, the following return air options are available:

Applications

The G71MPP gas furnace can be installed as shipped in
the upfiow position, Refer to figure 4 for clearances,

Page 7

1 - Return air from single side with transition which will
accommodate 20 x 25 x I in. (508x 635 x 25 ram) air filter.
(Required
to maintain proper air velocity.) See figure 5.

G71MPP applications which include side return air and
a condensate trap installed on the same side of the
cabinet require either a return air base or field-fabricated transition to accommodate an optional IAQ accessory taller than 14.5'"

2 - Return air from single side with optional RAB Return
Air Base. See figure 7.
3 - Return air from bottom.
4 - Return air from both sides.
5 - Return air from bottom and one side.
Refer to Engineering

Handbook

for additional

Removing the Bottom Panel

information.

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 6.

Side Return Air
(with transition and filter)

Removing the Bottom Panel
20" X 25" X 1"
(508mm X635mm X 25mm)
Air Filter

Return
Air
Plenum

Screw,/
Cap
Bottom

FIGURE 5
FIGURE 6
Optional Return Air Base
(Upflow Applications Only -- For use with B, C and D cabinets only)
f

t4
(356)

123(584)
Overall
(Maximum)

---_-_
1 Minimu_ I

11(279) I

2 Maximum

I' 1 Unit
air opening
side return

14_56)

FURNACE
FRONT
5-5/8
(143)
_.t

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

(Either Side)

OPTIONAL RAB
RETURN AIR BASE
-I_

24-1/2 (622) RAB-D (98M59)
FRONT

SIDE RETURN AIR
OPENINGS

23 (584)
27-5/8 (702)

--I1,-

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

_l
-T
3/4
(19)

7/8

VIEW

(22)

SIDE 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 ram).
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 7

Page 8

Settingan UpflowUnit
Whenthesidereturnairinletsareusedin an upflowapplication,itmaybenecessary
toinstallshimsonthebottom
ofthefurnace.If desired,usefield-supplied
corrosion-resistant5/16inchmachinebolts(4)andnuts(8)tolevelthe
furnace,Seefigure8,

Downflow Application Installation Clearances
Top

Left Side

NOTE - The maximum length of the bolt is 1-1/2 inches.

1 - Lay the furnace on its back and drill a 5/16 inch diameter hole in each corner of the furnace's bottom, See figure 8 for the correct location of the holes, Drill through
the bottom panel and the bottom flange of the cabinet.
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

Right Side

Boffom

flat washer may be added between the nut and the bottom of the unit.

Top

*Front

3 - Screw another nut onto the bolt on the inside of the fur-

Back

nace base. A flat washer may be added between the
nut and the bottom of the unit,

Sides

Vent

Floor

NC$

4 - Adjust the outside nut to the appropriate height and
tighten the inside nut to secure the arrangement,
Leveling

Inches (mm)

3/8
Furnace Front

*Front clearance in alcove installation must be 24 in. (610 ram).
Maintain a minimum of 24 in. (610 ram) for front service access.
tAllow proper clearances to accommodate condensate trap and
vent pipe installation.
SThe furnace may be installed on a combustible wood floor if an
optional additive base is installed between the furnace and the
combustible floor.

Bolt Installation

_¢

3/8

1-3/4
(44)

FIGURE 9
Installation on Non-Combustible

1-3/4
(44)

Leveling
Locati,

1 - Cut floor opening keeping in mind clearances listed on
unit rating plate. Also keep in mind gas supply connections, electrical supply, flue and air intake connections
and sufficient installation and servicing clearances,
See table 1 for correct floor opening size.

Leveling Bolt
Locations

Furnace
Bottom

3/8
(10)

Bolt

3/8
(10)

2 - Flange warm air plenum and lower the plenum into the
opening.
3 - Set the unit over the plenum and seal the plenum to
the unit,

1-3/4
(44)

4 - Ensure that the seal is adequate,

I-3/4 (44)

NON-COMBUSTIBLE

FIGURE 8
Downflow

Flooring

TABLE 1
FLOOR

Front to Rear

Applications

)PENING

SIZE

Side to Side

Model No.

The unit may be installed three ways in downflow applications: on non-combustible flooring, on combustible flooring
using an additive base, or on a reverse-flow cooling coil
cabinet. Do not drag the unit across the floor in the
downflow position. Flange damage will result.
Refer to figure 9 for clearances in downflow applications.

Page 9

in.

(17.5")

19 - 3/4

502

16 - 5/8

422

C Cabinet (21")

19 - 3/4

502

20-1/8

511

D Cabinet (24.5")

19 - 3/4

502

23 - 5/8

600

B Cabinet

NOTE - Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See dimension drawing on page 2.

Installation on Combustible Flooring
(Using an Additive Base)

5 - Set the furnace over the plenum,
6 - Ensure that the seal between the furnace and plenum

1 - When unit is installed on a combustible floor, an additive base must be installed between the furnace and

is adequate.
Installation

the floor, The base must be ordered separately. See
table 2 for opening size to cut in floor.

Ak CAUTION

on Cooling

Coil Cabinet

1 - Refer to reverse-flow coil installation instructions for
correctly sized opening in floor and installation of cabinet,
2 - When cooling cabinet is in place, set and secure the
furnace according to the instructions that are provided
with the cooling coil, Secure the furnace to the cabinet,
3 - Seal the cabinet and check for air leaks,

TABLE 2
ADDITIVE BASE FLOOR OPENING SIZE
Cabinet
Width
B Cabinet

(17.5")
C Cabinet
(21")
D Cabinet
(24.5")

Frontto

Catalog
Number

Rear

Return Air Opening -- Downflow

Units

Return air may be brought in only through the top opening
of a furnace installed in the downflow position.The following steps should be taken when installing plenum:

Side to Side

in.

11M60

559

18 - 3/4

476

11M61

559

22 - 3/4

578

2 - Sealing strips should be used to ensure an airtight seal
between the cabinet and the plenum.

11M62

559

25 - 3/4

654

3 - In all cases, plenum should be secured to top of fur-

1 - Bottom edge of plenum should be flanged with a
hemmed edge (See figure 11 or 12).

nace using sheet metal screws,
4 - Make certain that an adequate seal is made,
PLENUM

--*.._

(Field Provided)

I"'t'_

SECURE FROM

SUPPLY AIR PLENUM
G71MPP UNIT_
PROPERLY

__T

•

_L_UTSIDE

,VE
BASE

SEALING STRIP _
(Field Provided)

CABINET

v
......

Side View

II./

CABINET
SIDE PANEL

FIGURE 11

PLENUM
(Field Provided_-._

FIGURE 10

SEALING STRIP

2 - After opening is cut, set additive base into opening.
,_/.J.Field

3 - Check fiberglass strips on additive base to make sure

Provided)

they are properly glued and positioned,
4 - Lower supply air plenum into additive base until plenum flanges seal against fiberglass strips.
NOTE - Be careful not to damage fiberglass strips,
Check for a tight seal.

/
,

SECURE FROM
INSIDE CABINET

Side View
FIGURE 12

Page 10

CABINET
SIDE PANEL

Horizontal

Applications

The G71MPP furnace can be installed in horizontal applications with either right- or left-hand air discharge,
The G71MPP may also be installed as a unit heater. Either
suspend the furnace as shown in figure 14, or install the furnace on a field-fabricated raised platform. The unit must be
supported at both ends and beneath the blower deck to
prevent sagging,

3 - If unit is installed above finished space, fabricate a
drain pan fitted with a 1/2 inch or 3/4 inch N,P,T, fitting,
4 - Using 3/8 inch rods and support frame kit or field-fabricated supports, fabricate suspension hangers, keeping in mind front service access clearances.
5 - Mount unit on support frame as shown in figure 14,

Refer to figure 13 for clearances in horizontal applications,

6- Continue with exhaust, condensate
piping instructions,

Horizontal Application
Installation Clearances

TYPICAL HORIZONTAL

APPLICATION

BLOWER ACCESS

Right-Hand Discharge
Top

and intake line

3/8 in. RODS

PANEL

CONNECTION
Left End

) /

Air
Flow

Right End
•_

Bottom

Air
Flow

(Floor)**

Left-Hand Discharge
Top
Left End

Right

End
DRAIN PAN
SUPPORT

FRAME

Air
Flow

Front*

Back

Ends

Vent

Floor

finished space)

FIGURE 14

Bottom (Floor)**
Top

(to protect

*Front clearance in alcove installation must be 24 in. (610 ram).
Maintain a minimum of 24 in. (610 ram) for front service access.
**A 5-1/2" service clearance must be maintained below the unit to

Platform
_

Suspended Installation of Horizontal Unit

Route auxiliary drain line so that water draining from
this outlet will be easily noticed by the homeowner, If
necessary, run the condensate line into a condensate
pump to meet drain line slope requirements, The
pump must be rated for use with condensing furnaces,
Protect the condensate discharge line from the pump
to the outside to avoid freezing.

provide for servicing of the condensate trap.
:_For installations on a combustible floor, do not install the furnace directly on carpeting, tile or other combustible materials other than wood flooring.

FIGURE 13

If unit is suspended above finished space, hang the
field-provided drain pan below the support frame as
shown in figure 14. Leave 5-1/2 inches for service
clearance below unit for condensate trap,

Installation

of Horizontal

Unit

Select location for unit keeping in mind service and
other necessary clearances, See figure 13,

2- Construct a raised wooden frame and cover frame

NOTE- If unit is suspended, horizontal support kit (Cat No.
56J18 ordered separately) or equivalent is recommended
to ensure proper unit support and coil drainage.
1 - Select location for unit keeping in mind service and
other necessary clearances. See figure 13,
2 - Provide service platform in front of unit,

Page 11

with a plywood sheet, Provide a service platform in
front of unit, If unit is installed above finished space,
fabricate a drain pan to be installed under unit.
When installing the unit in a crawl space, a proper support platform may be created using cement blocks and
the horizontal support frame kit (ordered separately,

Lennoxpart number56J18).Positionthe support
frameon topoftheblocksandinstalltheunitonthe
frame.Leave5-1/2inchesfor serviceclearancefor
condensate
trap.
EXHAUST
INTAKE

PIPE

1 - Outer dimensions of cabinet should match those of the
unit heater, so the duct/grille cabinet installs flush with
the unit heater cabinet. See figure 16.
2 - Flange both ends of duct/grille cabinet so that screws
can be used to secure cabinet to discharge end of unit
heater.
3- To ensure proper operation, the duct/grille cabinet
must be at least 18 inches long.

*GAS
CONNECTOR

4 - Use #10-16 x 1/2 inch sheet metal screws to secure
duct/grille cabinet to unit, taking care not to damage internal components of unit heater when drilling holes or
installing screws. See figure 16,

*Gas connector may be
used
for
Canadian
installation
ff acceptable by local authority
having jurisdiction.

5 - Use adjustable, double-deflection grille(s) to distribute
discharge air, Adjust static pressure to be in the 0.06
inch to 0.10 inch w.c. range.
RAISED

CONDENSATE
LINE

SERVICE

PLATFORM

FIGURE 15
3 - Route auxiliary drain line so that water draining from
this outlet will be easily noticed by the homeowner. If
necessary, run the condensate line into a condensate
pump to meet drain line slope requirements. The
pump must be rated for use with condensing furnaces.
Protect the condensate discharge line from the pump
to the outside to avoid freezing.

DRAIN PA_

NOTE

FIGURE 16

4 - Set unit in drain pan as shown in figure 15. Leave 5-1/2
inches for service clearance below unit for condensate

Return Air -- Horizontal

trap.

Applications

Return air may be brought in only through the end of a furnace installed in the horizontal position. The furnace is
equipped with a removable bottom panel to facilitate installation. See figure 6.

5 - Continue with exhaust, condensate and intake piping
installation according to instructions.
G71MPP Installed

_ Wtlen installing duct/grille cabinet, take care not to damage internal unit
beater components
wben drilling boles or installing screws.

in Unit Heater Applications

Horizontal unit heaters may be installed either suspended
from the ceiling using the support frame kit or mounted on a
field-fabricated raised platform. The condensate trap must
be installed where it can be serviced at a later date.
The G71MPP may also be installed as a unit heater. Either
suspend the furnace from roof rafters or floor joists, as
shown in figure 14, or install the furnace on a field-fabricated raised platform, as shown in figure 15. The unit must
be supported at both ends and beneath the blower deck to
prevent sagging.

This unit is not equipped with a filter or rack, A field-provided filter is required for the unit to operate properly. Table
3 lists recommended filter sizes,
A filter must be in place whenever the unit is operating.
NOTE - In upflow applications where side return air filter is installed on same side as the condensate trap, filter rack must be installed beyond condensate trap to
a void interference.
TABLE 3
Furnace
Cabinet Width

Unit Heater Discharge Duct Guidelines
A field-fabricated and installed discharge air duct and grille
cabinet is suitable for use with the G71MPP heater. See figure 16, Keep the following items in mind when constructing
the cabinet,

B Cabinet

Side Return

Bottom Return

16X25Xl(1)

C Cabinet (21")

16X25Xl(1)

20X25Xl(1)

D Cabinet (24-1/2")

16X25Xl(2)

24X25Xl(1)

Page 12

(17-1/2")

Filter Size

TABLE 4
PIPING AND FITTINGS SPECIFICATIONS

Useindustry-approved
standardsto sizeandinstallthe
supplyandreturnairductsystem.Thiswillresultina quiet
andlow-staticsystemthathasuniformairdistribution.
NOTE - Operation of this furnace in heating mode (indoor
blower operating at selected heating speed) with an external static pressure which exceeds O.8 inches w.c. may result in erratic limit operation.

PIPE & FITTING MATERIAL
Schedule 40 PVC (Pipe)
Schedule 40 PVC (Cellular Core Pipe)

Return Air Plenum
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.
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. If a
filter is installed, size the return air duct to fit the filter frame.

All pipe, fittings, primer and solvent cement must conform
with American National Standard Institute and the American Society for Testing and Materials (ANSI/ASTM) standards. The solvent shall be free flowing and contain no
lumps, undissolved particles or any foreign matter that adversely affects the joint strength or chemical resistance of
the cement. The cement shall show no gelation, stratification, or separation that cannot be removed by stirring. Refer to table 4 for approved piping and fitting materials.

Page 13

F891
D2466

Schedule 40 CPVC (Pipe)

F441

Schedule 40 CPVC (Fittings)

SDR-21 CPVC or SDR-26 CPVC (Pipe)

If the furnace is installed without a cooling coil, a removable
access panel should be installed in the supply air duct. The
access panel should be large enough to permit inspection
(by reflected light) of the heat exchanger for leaks after the
furnace is installed. If present, this access panel must always be in place when the furnace is operating and it must
not allow leaks into the supply air duct system.

D1785

Schedule 40 PVC (Fittings)

SDR-21 PVC or SDR-26 PVC (Pipe)

Supply Air Plenum

ASTM
SPECIFICATION

Schedule 40 ABS Cellular Core DWV (Pipe)

F438
D2241
F442
F628

Schedule 40 ABS (Pipe)

D1527

Schedule 40 ABS (Fittings)

D2468

ABS-DWV (Drain Waste & Vent)
(Pipe & Fittings)

D2661

PVC-DWV (Drain Waste & Vent)
Pipe & Fittings)

D2665

_ CAUTION

Use PVC solvent cement as specified in ASTM D2564 and
ABS solvent cement as specified in ASTM D2235. Primers
and solvents must meet ASTM specifications. PVC primer
is specified in ASTM F 656. As an alternate, use all purpose
cement, as specified in ASTM performance requirements
D-2564, D-2235 and F493 to bond ABS, PVC, or CPVC
pipe when using fittings and pipe made d the same materials. Use transition solvent cement when bonding ABS to either PVC or CPVC. Low temperature solvent cement is recommended. Metal or plastic strapping may be used for vent
pipe hangers.
Uniformly apply a liberal coat of PVC primer for PVC or use
a clean dry cloth for ABS to clean inside socket surface of
fitting and male end d pipe to depth of fitting socket. Refer
to the procedure specified in ASTM D3138.
Canadian Applications Only - Pipe, fittings, primer and
solvent cement used to vent (exhaust) this appliance must
be certified to ULC S636 and supplied by a single
manufacturer as part of an approved vent (exhaust) system. When bonding the vent system to the furnace, use
ULC $636 approved One-Step Transition Cement to bond
the pipe to the flue collar, or to bond the 90 ° elbow or reducing 90 ° elbow to the flue collar. In addition, the first
three feet of vent pipe from the furnace flue collar must be
accessible for inspection.
Table 5 lists the available exhaust termination kits, as well
as vent pipe equivalencies which must be used when sizing
vent pipe. All Lennox vent terminations are PVC.

OUTDOOR

TERMINATION

TABLE 5
KITS AND CORRESPONDING

EQUIVALENCIES

Vent Pipe Length Equivalency (feet)
Outdoor
UNIT
MODEL

VENT
PIPE
DIA.
(in.)

Ex-

Outdoor

haust Accelerator
(Dia. X
Length)

1-1/2" X 12"

2"X

12"

1-112"
Concentric
Kit

2" Concentric

71M80

Kit

3" Concentric

69M29

60L46

2" Wall Plate

Kit

3" Wall

Kit

Plate

Kit

2" Wall
Ring

44J40
81J20

15F74

Not
Allowed

2-1/2

Not
Allowed

14"

Not
Allowed

1"*

2-1/2

Not
Allowed

2**

Not
Allowed

2**

Not
Allowed

4**

2-1/2

Not
Allowed

60C-090

60C-110

60D-135

field-provided

and installed

1-1/2" exhaust

accelerator.

**Requires

field-provided

Proposed

vent pipe size :

Step 2

Termination
kit catalog number :
Vent pipe equivalency
value from table 5 :

Step 3

Total number of 90 ° elbows required (indoors
X 5 =
equivalent feet of pipe

and outdoors)

Step 4

Total number of 45 ° elbows required (indoors
X 2.5 =
equivalent feet of pipe

and outdoors)

Step 5

Linear feet of straight

Step 6

Add equivalent feet of vent pipe listed in
steps 2 through 5.

Not
Allowed
Not
Allowed

and installed

Step 1

2" exhaust

Equivalent

pipe required

accelerator.

Feet

:
TOTAL

If the total is equal to, or less than, the allowable
maximum given in table 7, the proposed
pipe size is acceptable.
If the
total exceeds the maximum
allowed vent pipe length, repeat the process above using the next larger diameter pipe until
an acceptable
total is achieved.
NOTE - In Direct Vent systems, total the equivalent length of either the exhaust OR intake piping run, depending upon which
will be LONGER.
Intake and exhaust pipe diameter must be the same size and must be terminated
in the same pressure
zone. Intake and exhaust pipe should be roughly the same length.

Page 14

Kit

22G44
30G28

36B-070

*Requires

Ex-

haust Accelerator
(Dia. X
Length)

The G71MPP can be installed only as a Direct Vent gas
central furnace.
NOTE- In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing -- Size pipe according to
tables 6 and 7. Table 6 lists the minimum equivalent vent
pipe lengths permitted. Table 7 lists the maximum equivalent pipe lengths permitted.
Maximum vent length is defined as:
Total length (linear feet) of pipe,
Plus Equivalent length (feet) of fittings,
Plus Equivalent length (feet) of termination.
NOTE- Include ALL pipe and ALL fittings, both indoors
and outdoors. Measure equivalent length of intake and
exhaust pipe separately. Use the greater of the two
lengths to determine vent pipe diameter to be used for
both intake and exhaust.
Regardless of the diameter of pipe used, the standard roof
and wall terminations described in section Exhaust Piping

Terminations should be used. Exhaust vent termination
pipe is sized to optimize the velocity of the exhaust gas as it
exits the termination, Refer to table 8,
NOTE- The exhaust pipe should be offset a minimum of 12
inches to avoid the possibility of water droplets being released from the exhaust termination, The minimum exhaust vent length is 15 ft, Shorter exhaust vent lengths may
result in the discharge of water droplets from the exhaust
termination, in spite of the 12-inch vertical offset. See figure
17,
Each 90 ° elbow (including those provided with the furnace)
of any diameter is equivalent to 5 feet (1,52m) of vent pipe
of the same diameter. Two 45 ° elbows are equivalent to
one 90 ° elbow of the same diameter, One 45 ° elbow is
equal to 2,5 feet (.76m) d vent pipe of the same diameter.
In some applications which permit the use of several different sizes of vent pipe, a combination vent pipe may be
used. Contact Lennox' Application Department for assistance in sizing vent pipe in these applications.

Exhaust Pipe Offset

I
I
_'q 12" Min.

t1_

Upflow and Downflow Application
Rooftop Termination

Upflow and Downflow Application
Side Wall Termination

"br"
12" Min. "1_1

_1- 12" Min. -I_

Horizontal Application
Rooftop Termination

FIGURE 17

Page 15

Horizontal Application
Side Wall Termination

NOTE - The flue collar on all models is sized to accommodate 2" Schedule 40 flue pipe, When vent pipe which is
larger than 2" must be used in an upflow application, a 2"
elbow must be applied at the flue collar in order to properly
transition to the larger diameter flue pipe. This elbow must
be added to the elbow count used to determine acceptable
vent lengths. Assign an equivalent feet value to this elbow.
Contact the Application Department for more information
concerning sizing of vent systems which include multiple
pipe sizes.

TABLE 7
MAXIMUM VENT PIPE LENGTHS
MAXIMUM EQUIVALENT
ALTITUDE

0 - 7500
(0 - 2286 m)

7501 - 10000
(2287 - 3048 m)

Use the following steps to correctly size vent pipe diameter,
Refer to Vent Pipe Size Determination
Worksheet on
page 65.

G71MPP
MODEL

2"
PIPE

LENGTH FEET
2-1/2"
3"
PIPE
PiPE

VENT
4"
PiPE

070

135

150

250

090
110"

50
20

100
60

125
125

225
200

135"*
070

n/a
60

n/a
125

125
150

180
250

090
110"
135"*

25
n/a
n/a

60
40
n/a

125
90
70

225
200
180

n/a -- Not allowed.

1 - Determine the vent termination and its corresponding
equivalent feet value according to table 5,

*G 71MPP-60C-110
into unit flue collar.

2 - Determine the number of 90 ° elbows required for both
indoor and outdoor (e,g. snow riser) use. Calculate the
corresponding equivalent feet of vent pipe.
3 - Determine the number of 45 ° elbows required for both
indoor and outdoor use, Calculate the corresponding

**G 71MPP-60D-135 must have 3" to 2" reducing eli (supplied) installed
directly into unit flue collar.
NOTE - Elbows and pipe required for vent terminations must be added
when calculating equivalent vent length.

All cementing of joints should be done according to the
specifications outlined in ASTM D 2855.

equivalent feet of vent pipe,
4 - Determine the length of straight pipe required,
5- Add the total equivalent feet calculated in steps 1
through 4 and compare that length to the maximum
values given in table 7 for the proposed vent pipe diameter. If more than one diameter of pipe is being
used, use the appropriate value from table 7 for the
larger sized pipe, If the total equivalent length required
exceeds the maximum equivalent length listed in the
appropriate table, evaluate the next larger size pipe.

AIMPORTANT

must have 90 ° street eli (supplied) installed directly

,& DANGER

1 - Measure and cut vent pipe to desired length,
2 - Debur and chamfer end of pipe, removing any ridges
or rough edges, If end is not chamfered, edge of pipe
may remove cement from fitting socket and result in a
leaking joint,
3 - Clean and dry surfaces to be joined,
4- Test fit joint and mark depth of fitting on outside of
pipe,
5 - Uniformly apply a liberal coat of PVC primer for PVC or
use a clean dry cloth for ABS to clean inside socket
surface of fitting and male end of pipe to depth of fitting
socket,

TABLE 6
MINIMUM VENT PIPE LENGTHS
G71MPP
MODEL

MIN. EQUIV.
VENT LENGTH

070,090
110"*

15 ft.*

EXAMPLE
5 ft. plus 2 elbows of 2", 2-1/2", 3"
or 4" diameter pipe

NOTE - Furnace flue collar and air inlet fitting are both
made of ABS material. Use transition solvent cement

5 ft. plus 2 elbows of 2-1/2" 3" or 4"
diameter pipe

when joining ABS fittings to PVC pipe,

must have 90 ° street eli (suppfied) installed directly

6 - Promptly apply solvent cement to end of pipe and inside socket surface of fitting. Cement should be applied lightly but uniformly to inside of socket, Take care
to keep excess cement out of socket, Apply second
coat to end of pipe,

***G71MPP-60D-135
must have 3" to 2" reducing eli (supplied) installed
directly into unit flue collar.

NOTE- Time is critical at this stage. Do not allow primer to dry before applying cement.

5 ft, plus 2 elbows of 3" or 4"
diameter pipe

135"**
*Any approved
length listed.

termination

**G71MPP-60C-110
into unit flue collar.

ma , be added to the minimum

equivalent

Page 16

7 - Immediately
afterapplyinglastcoatofcementtopipe,
andwhilebothinsidesocketsurfaceandendofpipe
arewetwithcement,forcefullyinsertendofpipeinto
socketuntilitbottoms
out.TurnPVCpipe1/4turnduringassembly
(butnotafterpipeisfullyinserted)
todistributecementevenly.DONOTturnABSor cellular
corepipe.
NOTE - Assembly should be completed within 20 seconds after last appfication of cement. Hammer blows
should not be used when inserting pipe.
8 - After assembly, wipe excess cement from pipe at end
of fitting socket. A properly made joint will show a bead
around its entire perimeter. Any gaps may indicate a
defective assembly due to insufficient solvent.
9 - Handle joints carefully until completely set.

The thickness of construction through which vent pipes
may be installed is 24" (610mm) maximum and 3/4"
(19mm) minimum. If a G71MPP furnace replaces a furnace
which was commonly vented with another gas appliance,
the size d the existing vent pipe for that gas appliance must
be checked. Without the heat of the original furnace flue
products, the existing vent pipe is probably oversized for
the single water heater or other appliance. The vent should
be checked for proper draw with the remaining appliance.
1 - Use recommended piping materials for exhaust piping.
2 - Secure all joints so that they are gas-tight using approved cement.
Suspend piping using hangers at a minimum of every
5 feet (1.52m) for schedSTRAPPING
ule 40 PVC and every 3
(metal, plastic
feet (.91m) for ABS-DWV,
large wire
PVC-DWV, SPR-21 PVC,
and SDR-26 PVC piping.
ties)
A suitable hanger can be
fabricated by using metal
FIGURE 18
or plastic strapping or a
large wire tie.

Exhaust

Piping (Figures

19 and 20)

NOTE- A 2" diameter PVC street ell is located on the blower deck of 60C-110 units, Street ell must be_glued using
transition solvent cement directly into the unit flue collar.
See figure 19. A 3"to 2" PVC reducing ell is located on the
blower deck of the 60D-135 units, In upflow or downflow
applications,
the reducing ell must be glued using transition solvent cement directly into the unit flue collar.
1 - Choose the appropriate side for venting in upflow or
downflow positions, Exhaust piping exits from the top
of the unit in horizontal air discharge applications.
Glue the field-provided exhaust vent pipe (or provided
street ell or reducing ell in upflow or downflow applications) to the flue collar, All PVC cement joints should
be made according to the specifications outlined in
ASTM D 2855. Refer to pipe and fittings specifications
and gluing procedures,

A, IMPORTANT

2 - All horizontal runs of exhaust pipe must slope back toward unit. A minimum of 1/4" (6mm) drop for each 12"
(305mm) of horizontal run is mandatory for drainage.
Horizontal runs of exhaust piping must be supported
every 5 feet (1,52m) using hangers.
NOTE - Exhaust piping should be checked carefully to
make sure there are no sags or low spots.
3 - On the opposite side of the cabinet, glue the provided
2" vent plug into the unused flue collar,
4-

Route piping to outside of structure, Continue with
installation following instructions given in piping termination section.

A, CAUTION

3- In areas where piping penetrates joists or interior
walls, hole must be large enough to allow clearance on
all sides of pipe through center of hole using a hanger.
4 - Isolate piping at the point where it exits the outside wall
or roof in order to prevent transmission of vibration to
the structure.
5 - When furnace is installed in a residence where unit is
shut down for an extended period of time, such as a
vacation home, make provisions for draining condensate collection trap and lines.

Page 17

Ak CAUTION

TYPICAL

EXHAUST
PIPE CONNECTIONS
IN UPFLOW OR DOWNFLOW

AND CONDENSATE
TRAP INSTALLATION
DIRECT VENT APPLICATIONS

(Right-Hand Exit in Upflow Application

Shown)

45°
MAX

2-1/2",
3", OR

45 °
MAX

PLUG
TRANSiTiON

G71 MPP-070,
2"

VENT PLUG
(Must be
glued in
place)

or -090 with
2-1/2", 3", or4"
vent pipe

SIDE ViEW

2-1/2", p:>_]

PLUG

CONDENSATE
TRAP
(Must be installed
on same side as
exhaust piping)

3":4OR _
TRANSITION _

TRANSmON
(use only if 4"
pipe is
required)

Ft
"2" diameter street elbow provided.
**3" to 2" diameter reducing elbow provided.
*** Max 2" pipe length between reducing
elbow and transition when 4" pipe is used.

G71MPP-110
with
2-1/2", 3", OR 4"
vent pipe

....

G71MPP-135 with
3" OR 4" vent pipe

FIGURE 19
TYPICAL
EXHAUST
PIPE CONNECTIONS
HORIZONTAL DIRECT VENT APPLICATIONS
(Horizontal Right-Hand Air Discharge Application Shown)

*2" maximum length
for -135 only.

-36B-070
-36C-090
-60C-090
.60C.110"
.60D-135"

Intake Piping
The G71MPP furnace may be installed only in direct vent
applications,
The G71MPP unit is designed for either left-side or rightside air intake connections in either upflow or downflow applications. In horizontal applications, air intake must be
brought in through the top, Intake air piping is independent
of exhaust piping,

TRANSiTiON

-36B-070
DO NOT transition from
smaller
to larger
pipe
size in horizontal
runs.

-60C-090
,,1"36C'090

FIGURE 20

Page 18

TYPICAL AIR INTAKE PIPE CONNECTIONS
UPFLOW OR DOWNFLOW DIRECT VENT APPLICATIONS
(Right-Hand Exit in Upfiow Application Shown)

3" OR
2-1/2",
4'

TRANSITION

[:_

[_2"

TRANSITION

PLUG
(Must be
glued in
place)
-36B-070
-36C-090
-60C-090

-36B-070
-36C-090
-60C-090
-60C-110

*Limit pipe length to 4" in
G 71MPP-135 applications.

FIGURE 21
TYPICAL
AIR INTAKE PIPE CONNECTIONS
HORIZONTAL DIRECT VENT APPLICATIONS
(Horizontal Right-Hand Air Discharge Application Shown)

*Limit pipe
length
to 4" in
- 135 applications.

-36B-070
-36C-090
-60C-090
-60C-110
-60D-135"
TRANSITION
2"*
2-1/2",
3" OR 4"
-36B-070
-36C-090
-60C-090
-60C-110

-36B-070
-36C-090
-60C-090

2,,L_

FIGURE 22

Page 19

-36B-070
-36C-090
-60C-090
-60C-110
-60D-135"

VENT TERMINATION
CLEARANCES
FOR INSTALLATIONS
IN THE USA AND CANADA*

[]

- G71MPP VENT TERMINATION

- AIR INLET OF OTHER APPLIANCE

D
!
A - Clearance above grade - 12 in. (305mm) minimum.
B - Clearance to window or door that may be opened for vent installations
in USA- 12 in (305mm) minimum.
for vent installations
in Canada - 12 in. (305mm) minimum for appliances _ 100,000 Btuh (30 kW);
36 in (09m) minimum for appliances > 100,000 Btuh (30
kW)
C - Do not position terminations

directly under roof eaves.

D - Clearance to electric meters, gas meters, regulators, and
refief equipm ent for vent installations
in USA -48 in (1219mm) minimum.
for vent installations
in Canada - see current edition of
CSA B149 Code

E - Clearance to non-mechanical air supply inlet or outlet
for vent installations
in USA -48 in. (1219mm) minimum
horizontal and below, 12 in, (305ram) minimum above.
for vent installations
in Canada - 12 in. (305mm) minimum for appliances _ 100,000 Btuh (30 kW);
36 in, (0.9m) minimum for appliances > 100,000 Btuh (30
kW).
F - Clearance to mechanical air supply inlet -for vent installations
in USA - 36 in. minimum (914mm).
G - Clearance to mechanical air supply inlet -for vent installations
in Canada - 72 in. (1829mm)
mum.

mini-

H - Do notpoint terminations into recessed areas such as window wells, stairwells or alcoves.
J - Do not position terminations
way.

directly above a pubfic walk-

* Note (I) Dimensions are from the current edition of The National Fuel Gas Code - ANSI-Z22& 1/NFPA 54 for USA installations. In Canada, refer to current edition of CSA B149 installation codes. Local codes or regulations may require different
clearances.
(11)In Non-Direct Vent installations, combustion air is taken from indoors and the flue gases are discharged to the outdoors.

FIGURE 23

Page 20

Details of Intake and Exhaust Piping Terminations for
Direct Vent Installations
NOTE- In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged to outdoors.
Intake and exhaust pipes may be routed either horizontally
through an outside wall or vertically through the roof. In attic or closet installations, vertical termination through the
roof is preferred. Figures 24 through 32 show typical terminations.
1 - Exhaust and intake exits must be in same pressure
zone. Do not exit one through the roof and one on the
side. Also, do not exit the intake on one side and the
exhaust on another side of the house or structure.

9 - Based on the recommendation of the manufacturer, a
multiple furnace installation may use a group of up to
four wall termination kits assembled together horizontally, as shown in figure 30,
TABLE 8
EXHAUST PIPE TERMINATION SIZE REDUCTION
G71MPP
MODEL

8 - If intake and exhaust piping must be run up a side wall
to position above snow accumulation or other obstructions, piping must be supported every 3 ft. (.9m) as
shown in figure 18. Refer to figure 28 for proper piping
method. In addition, the wall termination kit must be
extended for use in this application. See figure 31.
When exhaust and intake piping must be run up an
outside wall, the exhaust piping must be terminated
with pipe sized per table 8. The intake piping may be
equipped with a 90 ° elbow turndown. Using turndown
will add 5 feet (1.5m) to the equivalent length of the
pipe.

Page 21

Pipe Size

2", 2-1/2", 3" or4"
2", 2-1/2", 3" or4"

110
135

2-1/2", 3" or4"
3" or 4"

2"*
2"*

*Approved 3" concentric termination

1-1/2"

kit terminates

3" (76) MAX.

--'_l

with 2-5/8" ID pipe.

SIZE TERMINATION

UNCONDITIONED
PIPE
PER TABLE 8.
ATTIC SPACE

8" (203)
MIN

1/2" (13) FOAM
INSULATION IN
UNCONDITIONED

SPACE

Y
/

Inches

2" (50) or
3" (80) PVC

(mm)

PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
DIRECT

7 - On field supplied terminations, the end of the exhaust
pipe must extend a minimum of 8" (203mm) beyond
the end of the intake pipe.

Termination

090

exhaust back into intake pipe.
6 - On field supplied terminations for side wall exits, exhaust piping should extend a maximum of 12 inches
(305mm) beyond the outside wall unless supported.
Intake piping should be as short as possible. See figure 25.

Pipe Size

070

2 - Intake and exhaust pipes should be placed as close
together as possible at termination end (refer to illustrations). Maximum separation is 3" (76mm) on roof
terminations and 6" (152mm) on side wall terminations.
3 - If necessary, install a field-provided transition to adapt
larger vent pipe size to termination pipe size.
4 - On roof terminations, the intake piping should terminate straight down using two 90 ° elbows (See figure
24).
5 - Exhaust piping must terminate straight out or up as
shown. In rooftop applications, a reducer may be required on the exhaust piping at the point where it exits
the structure to improve the velocity of exhaust away
from the intake piping. See table 8.
NOTE - Care must be taken to avoid recirculation of

Exhaust

VENT

ROOF

(15F75

TERMINATION

KIT

or 44J41)

FIGURE 24
12" (305) MAX.
1/2" (13)ARMAFLEX
INSULATION
IN

UNCONDITIONED

I(unless
_

supported)
I=

SPACE

1/2" (13)
INSULATION
ARMAFLEX

R E_)R;(_'_iEMDAy
BE REQUIRED

TO ADAPT
PIPE SIZE TO
LARGERTERMINATIoNVENT
_
"=_

_UM
_

ou s,o V
IJ
WALL

Inches (rnm)

6" (152)

MINIMUM

TOP VIEW WALL RING KIT
(15F74)

FIGURE 25

2" (51)

PVC

L,No

EXHAUST
EXHAUST
TERMINATION

12" (305) ABOVE
AVERAGE SNOW
ACCUMULATION

INTAKE
Inches (ram)

('_

VENT
J)r'_... t
(with optional/I
L__J
elbow)
/

INTAKE
TERMINATION

VENT

Front View

1/2" (13) Foam Insulation
in Unconditioned
Space

Side View

FIELD-PROVIDED
REDUCER
MAY BE REQUIRED
TO ADAPT
LARGER
VENT
PIPE

EXHAUST

SIZE

PROVIDED
REDUCER MAY
BE REQUIRED
TO ADAPT
LARGER VENT
PIPE SIZE TO |
FIELDL
TERMINATION

TERMINATION

INTAKE

DIRECT VENT CONCENTRIC ROOFTOP TERMINATION
(71 M80, 69M29 or 60L46)

Inches

FIGURE 26

EXHAUST

INTAKE
VENT
(with optional
elbow)

(ram)

OUTSIDE

WALL

DIRECT VENT WALL TERMINATION KIT
(22G44, 44J40, 30G28 or 81J20)

FIGURE 29

INTAKE
TERMINATION
Inches

VENT

EXHAUST

TERMINATION

EX.AUST

f
FIELD-PROVIDED

[_)l_ _

_',
L,__,_

1 127 III

(with optional
elbow /

18" MAX.
(457) "_
_>_._

Inches (mm)

DIRECT VENT CONCENTRIC WALL TERMINATION
(71 M80, 69M29 or 60L46)

Side View

12" (305) MAX. for 2" (51)
(unless supported)

,_11

OUTSIDE WALL
SIZE
---_TERMINATION
/
PIPE PER
/
TABLE 8.

12" (305) ABOVE
AVERAGE SNOW
ACCUMULATION

REDUCER MAY
BE REQUIRED TO
ADAPT LARGER
VENT PIPE SIZE
TO TERMINATION
1/2" (13) FOAM
INSULATION IN
UNCONDITIONED
SPACE

1/2" (13) FOAM
INSULATION
SIDE

Front View
EXHAUST

VIEW

DIRECT VENT WALL RING TERMINATION
(15F74)
See venting table 7 for maximum venting lengths with this arrangement.

FIGURE 28

Page 22

VENT

INTAKE

__
_

FIGURE 30

FIELD-PROVIDED

'
/2" (i 05)

(with

OPTIONAL
VENT TERMINATION
FOR MULTIPLE
INSTALLATION
OF DIRECT VENT WALL TERMINATION

UNCONDITIONED
SPACE

PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES EVERY
36" (914)

12"
'

_1_-'-,-,_

FIGURE 27

Inches(ram)

"_'_'_ _-/,\_)_

,NTAKE-VENT
"" i <
II¢-:tI
5:
.... III::
VENT
I°_°ll
_°
I°_°ll
°_ " "I

12" (305) Min.
above grade.

REDUCER MAY
BE REQUIRED TO
ADAPT LARGER
VENT PiPE SIZE
TO TERMINATION

_'_

EXHAUST--_

VENT
optional
elbow)

UNIT
KIT (30G28)

12" (305) MAX. for 2" (51)
20" (508) MAX. for 3" (76)
(unless supported)
f-

INTAKE
AIR

//
//
//

71- --

(C_
i _-_-

Inches

12"

(ram)

-Iq

1
_
_
--J .....
IJ

__11_[_/_

8" (203)

EXHAUST
AIR

INTAKE
AIR

EXHAUST
AIR

!1 II
_
_
12"(305)
)1
Minimum
5"
iiiililili_!!iii!ii!ii!ii!ii!ii!ii!ii!ii!ii!i_!i!!i_i_ii_iiii_;_;!
ABOVE
GRAOE (127

12" MIN.
(305)
Above Grade

Side View

GRADE

COVER EXHAUST
VENT WITH
1/2" (13)
FOAM
INSULATION

GRADE

Front View
WALL TERMINATION

DIRECT VENT TERMINATION
KIT (22G44, 44J40, 30G28 or 81J20) EXTENDED VENT FOR GRADE CLEARANCE

FIGURE 31
G71MPP DIRECT VENT APPLICATION
USING EXISTING CHIMNEY
STRAIOHT-CUTOR
ANGLE-CUT
IN DIRECTION
OF ROOF

SLOPE

NOTE- If necessary the condensate trap may be installed
in an alternate location in upflow applications using kit
number 76M20.
CONDENSATE TRAP LOCATIONS
(Unit shown in upf!ow position)

EXHAUSTVENT
1_" (13ram)
WEATHERPROOF
INSULAT_N

8 12
(203mm 30_,m)

INTAKE
INSULATION

P_PE
(opfl_al)

SHEET

SHOULDER
OF FITQNGS
PROVIDE SUPPORT
OF PIPE ON TOP PLATE
i

ALTERNATE

METALTOP
PLATE

L--\:;

..,_
._AKE
P_PE

MINIMUM
12"
(305ram) ABOVE
ROOF

*SIZE TERMINATION
PIPE PER TABLE 8.

Horizontal
left and
optional
downfiow

_]
J

Horizontal
right and
optional
downflow

Optional
upf!ow

Optional
upflow

NOTE - Do not discharge exhaust gases directjy into any chimney or vent stack. If vertical discharge through an existing unused chimney or stack is required,
insert piping
inside chimney until the pipe open end is above top of chimney and terminate
as illustrated. In any exterior portion of chimney,
the exhaust vent must be insulated.

FIGURE 32
Condensate Piping
This unit is designed for either right- or left-side exit of condensate piping in either upfiow or downflow applications;
however, it must be installed on the same side of the unit as
the exhaust piping. In horizontal applications, the condensate trap should extend below the unit. A 5-1/2" service
clearance is required for the condensate trap. Refer to figure 33 for condensate trap locations.

Page 23

NOTE - In upflow applications where side return
air filter is installed on same side as the condensate trap, filter rack must be installed beyond
condensate trap to avoid interference.
FIGURE 33

1 - Determine
whichsidecondensate
pipingwillexitthe
unit,Removeplugsfromthecondensate
collaratthe
appropriate
locationonthesideof theunit.

Condensate line must be sloped downward away from
condensate trap to drain, If drain level is above condensate trap, condensate pump must be used, Condensate drain line should be routed within the condi-

NOTE - The condensate trap is factory-shipped with
two rubber Q-rings and two rubber clean-out caps
installed. Check to make sure that these items are in

tioned space to avoid freezing of condensate and
blockage of drain line, If this is not possible, a heat
cable kit may be used on the condensate trap and line.
Heating cable kit is available from Lennox in various
lengths; 6 ft. (1.8m) - kit no. 26K68; 24 ft. (7.3m) - kit
no. 26K69; and 50 ft, (15.2m) - kit no, 26K70,

place before installing the trap assembly.
2-

Install condensate trap onto the condensate collar.
Use provided HI/LO screws to secure two upper
flanges of the trap to the collar, Use provided sheet
metal screw to secure bottom trap flange to side of
unit, See figure 34,
NOTE - In upflow and downflow applications, condensate trap must be installed on the same side as
exhaust piping.

CAUTION

5 - If unit will be started immediately upon completion of
installation, prime trap per procedure outlined in Unit
Start-Up section.
6- Glue the provided cap onto the unused condensate
drain line stub.

CONDENSATE
3- The grey-colored condensate trap (101661-01) provided with the unit is manufactured using ABS material. This is the only trap that is to be used with this unit,
Use ABS to PVC transition solvent cement to glue a
field-provided PVC coupling or PVC pipe to the trap.
Install a tee and vent pipe near the trap,

O-RINGS

ASSEMBLY

HI/LO SCREWS
(DO NOT use power
driver. Hand4ighten
using screw driver.)

/VENT

NIPPLE

NOTE- The condensate trap drain stubs (both sides)
have an outer diameter which will accept a standard
3/4" PVC coupling. The inner diameter of each stub
will accept standard 1/2" diameter PVC pipe.

TEE

NOTE - Vinyl tubing may be used for condensate
drain. Tubing must be 1-1/4" QD X 1" ID and should be
attached to the drain stubs on the trap using a hose
clamp.

CAP

4 - Glue the field-provided drain line to the tee, Route the
drain line to an open drain. As an alternate, clear vinyl
tubing may be used to drain condensate away from
the trap. Secure the vinyl tubing to the drain stubs on
the trap using a hose clamp. Do not overtighten the
hose clamp.

Page 24

NIPPLE

COUPLING
_

CLEAN-OUT ACCESS
(both sides)

"_NDENSATE
(grey)

SCREW

FIGURE 34

TRAP

,IMPORTANT
-&CAUTION
MANUAL MAIN SHUT-OFF
VALVE WILL NOT HOLD

AWARNING

NORMAL TEST PRESSURE

FURNACE

ISOLATE
GAS VALVE
I

CAP .------...._t-t

1 - Gas piping may be routed into the unit through either
the left- or right-hand side. Supply piping enters into
the gas valve from the side of the valve as shown in
figures 36 and 37.
2 - When connecting gas supply, factors such as length of
run, number of fittings and furnace rating must be considered to avoid excessive pressure drop. Table 9 lists
recommended pipe sizes for typical applications.
NOTE - Use two wrenches when connecting gas piping to avoid transferring torque to the manifold.
3 - Gas piping must not run in or through air ducts, clothes
chutes, chimneys or gas vents, dumb waiters or elevator shafts. Center gas line through piping hole. Gas
line should not touch side of unit. See figures 36 and
37.

FIGURE 35
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.
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.).

4 - Piping should be sloped 1/4 inch per 15 feet (6mm per
5.6m) upward toward the gas meter from the furnace.
The piping must be supported at proper intervals, every 8 to 10 feet (2.44 to 3.05m), using suitable hangers
or straps. Install a drip leg in vertical pipe runs to serve
as a trap for sediment or condensate.

AIMPORTANT

AWARNING

5 - A 1/8" N.P.T. plugged tap or pressure post is located
on the gas valve to facilitate test gauge connection.
See figures 44.
6 - In some localities, codes may require installation of a
manual main shut-off valve and union (furnished by installer) external to the unit. Union must be of the
ground joint type.
Upflow Application
Left Side Piping

Upflow Application
Right Side Piping
(Alternate)

AUTOMATIC
GAS
VALVE

(Standard)

(with manual
shut-off valve)

MANUAL
MAIN SHUT-OFF
VALVE

GROUND
JOINT
UNION

JOINT
UNION
DRIP

DRIP LEG

FIELD
PROVIDED
AND INSTALLED

Figure 36
Page 25

LEG

Horizontal Applications
Possible Gas Piping Configerations
MANUAL
MAIN SHUT-OFF
VALVE

MANUAL
MAIN SHUT-OFF
VALVE

Horizontal Application
Left-Side Air Discharge

J
GROUND
JOINT
UNION

DRIP LEG

•

Horizontal Application
Right-Side Air Discharge

-q

MANUAL
MAIN SHUT-OFF
VALVE

LUlII
_31 II
_'-J 2-"

GROUND
JOINT

UNION
DRIP LEG

FIGURE 37
TABLE 9
GAS PIPE CAPACITY - FTZ/HR (kL/HR)
Nominal
Iron Pipe Size
-Inches(ram)

Internal
Diameter
-Inches(ram)

Length
10

(3.048)

(6.096)

(9.144)

40
(12.192)

of Pipe-Feet(m)

50
(15.240)

60
(18.288)

70
(21.336)

1/4
(6.35)
3/8
(9.53)

,364
(9.246)

43
(1.13)

29
(.82)

24
(.68)

20
(.57)

18
(.51)

16
(.45)

15
(.42)

.493
(12.522)

95
(2.69)

65
(1.84)

52
(1.47)

45
(1.27)

40
(1.13)

36
(1.02)

1/2
(12.7)

.622
(17.799)

175
(4.96)

120
(3.40)

97
(2.75)

82
(2.32)

73
(2.07)

3/4
(19.05)

.824
(20.930)

360
(10.19)

250
(7.08)

200
(5.66)

170
(4.81)

1
(25.4)

1.049
(26.645)

680
(19.25)

465
(13.17)

375
(10.62)

1-1/4
(31.75)

1,380
(35.052)

1400
(39.64)

950
(26.90)

1-1/2
(38.1)

1.610
(40.894)

2100
(59.46)

2
(50.8)

2,067
(52.502)

2-1/2
(63.5)

8O
(24.384)

9O
(27.432)

100
(30.480)

33
(.73)

14
(.40)
31
(.88)

13
(.37)
29
(.82)

12
(.34)
27
(.76)

66
(1.87)

61
(1.73)

57
(1.61)

53
(1.50)

50
(1.42)

151
(4.28)

138
(3.91)

125
(3.54)

118
(3.34)

110
(3.11)

103
(2.92)

320
(9.06)

285
(8.07)

260
(7.36)

240
(6.80)

220
(6.23)

205
(5.80)

195
(5.52)

770
(21.80)

660
(18.69)

580
(16.42)

530
(15.01)

490
(13.87)

460
(13.o3)

430
(12.18)

400
(11.33)

460
(41.34)

1180
(33.41)

990
(28.03)

900
(25.48)

810
(22.94)

750
(21.24)

690
(19.54)

650
(18.41)

620
(17.56)

3950
(111.85)

2750
(77.87)

2200
(62.30)

1900
(53.80)

1680
(47.57)

1520
(43.04)

1400
(39.64)

13oo
(36.81)

1220
(34.55)

1150
(32.56)

2A69
(67.713)

6300
(178.39)

4350
(123.17)

3520
(99.67)

3000
(84.95)

2650
(75.04)

2400
(67.96)

2250
(63.71)

2050
(58.05)

1950
(55.22)

1850
(52.38)

3
(76.2)

3,068
(77.927)

11000
(311.48)

7700
(218.03)

6250
(176.98)

5300
(150.07)

4750
(134.50)

4300
(121.76)

3900
(110.43)

3700
(lO4.77)

3450
(97.69)

3250
(92.03)

4
(101.6)

4.026
(102.260)

23000
(651.27)

15800
(447.39)

12800
(362.44)

10900
(308.64)

9700
(274.67)

8800
(249.18)

8100
(229.36)

7500
(212.37)

7200
(203.88)

6700
(189.72)

NO TE - Capacity given in cubic feet of gas per hour (kilo liters of gas per hour) and based on O.60 specific gravity gas.

Page 26

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 harn-

ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures

&CAUTION

ess to protect it from damage.
Refer to figure 40 and table 10 for field wiring and figure 41
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.
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.

INTERIOR MAKE-UP BOX INSTALLATION

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.

MAKE-UP
BOX

18-gauge wire or larger that is suitable for Class II rating for thermostat connections.

Right Side

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.

6
FIGURE 38

7 - One line voltage "EAC" 1/4" spade terminal is provided
on the furnace integrated control. 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 one of the provided neutral terminals. See
figure 42 for integrated control configuration. This terminal is energized when the indoor blower is operating.

INTERIOR MAKE-UP BOX INSTALLATION

Left side

Complete the wiring connections to the equipment.
Use the provided unit wiring diagram and the field wiring diagram shown in figure 40 and table 10. Use

MAKE-UP
BOX

One line voltage *'HUM" 1/4" spade terminal is provided on the furnace integrated control. Any humidifier
rated up to one amp can be connected to this terminal
with the neutral leg of the circuit being connected to
one of the provided neutral terminals. See figure 42 for
integrated control configuration. This terminal is energized in the heating mode when the combustion air inducer is operating.
9 - One 24V "H" terminal is provided on the furnace integrated control terminal block. Any humidifier rated up
to 0.5 amp can be connected to this terminal with the
ground leg of the circuit being connected to either
ground or the "C" terminal. See figure 42 for integrated
control configuration.

FIGURE 39

Page 27

10-Installtheroomthermostataccordingto the instructionsprovidedwiththethermostat,
Seetable10for
thermostatconnections.If the furnace is being
matchedwith a heatpump,referto the instruction
packaged
withthedualfuelthermostat,
ThermostatSelection
TheG71MPPisdesignedtooperateina variableratecapacitymodeusinga two-stage
thermostat.
TheG71MPP
willautomatically
adjustfiringratebaseduponthermostat
cycletimes,Foroptimalperformance,Lennoxrecommendsuseof a highqualityelectronicdigitalthermostat
withadjustable
settings
for1ststage/ 2rid stage on / off dif-

stage upstage timer disabled, or set to maximum (1 hr minimum).
Indoor Blower Speeds
1 - When the thermostat is set to "FAN ON," the indoor
blower will run continuously at a percentage of the second-stage cooling speed when there is no cooling or
heating demand. The percentage is set using DIP
switches 6 and 7,
2 - When the G71MPP is running in the heating mode, the
integrated control will automatically adjust the blower
speed to match the furnace firing rate. This speed can
be adjusted up or down by 7,5% or 15% using DIP
switches 14 through 16 for the low heat speed and 17
through 19 for the high heat speed.
3 - When there is a cooling demand, the indoor blower will
run on the cooling speed designated by the positions
of DIP switches 8 through 11,

ferentials and adjustable stage timers.
Lennox recommends the following two-stage thermostat
set-up for optimal variable rate capacity mode:
First heat stage differential set to 1/2 to 1 degree F; second
heat stage differential set to 1/2 or 1 degree F; second heat

TYPICAL G71MPP FIELD WIRING DIAGRAM
$102(2)
120V ACC

COMBUSTION AIR

G
SWITCH

LIMIT

BACKUP

GAS

SECONDARY

VALVE

PREGGURE GAG

GlIB
LIMIT

BURNERS

HIGH HEAT
PRESSURE

USE COPPER
I

CONDUCTORS

FIELD INSTALLED
FIELD INSTALLED

LI -_--ili

ONLY.

LOW

s51
E

I@@@®©@@I
j

SUPPLIED

AND

ARE

WIRE
HARNESS

HARNESS
T8

FURNACE

TASLE

SENSOR

3159

ROLLOUT
SWITCH

FLAME

_P159

E)-3156

A92
INTEGRATED

CONTROL

NOT

USED

MATCH

Ii
i

_--_

SWITCH
$128(1)

/k_

LOW

RDLLDUT
SWITCH

HEAT

PRESSURE
SWITCH
SOl(If
SECONDARY
LIMIT

TRANSFORMER
3246

®
821(2)
SECONDARY

LIMIT

BF n
23456

[]

P46

183456
CB8
CIRCUIT
BREAKER

L .......

I
_GEE

FLAME

IGNITOR L_

i
i

ACC WIRE

TERHINALS

_FLAME

t3c_

',
i
,,
,,
FIELD

HEAT

PRESSURE
SWITCH

CLASS 0 24V
LINE VOLTAGE

$1
ROOM THERMOSTAT

@
$1£8(G)

-i

L_-_77

SIZE

_),_)SENSOR
TO78

POWER
CHOKE
L1B

I--4--L-:___
I
I

....

I
I
I

II Z_ _
INDOOR

DDISCHAROE'
TERHINAL

OUTDOOR
UNIT

BOARD

C
_24_

INPUT

FIGURE 40

Page 28

..........

I
I 11 Ill

'I--

90DQ
t
I

I
i

BLOWER
MOTOR

F _)

TABLE 10
Field Wiring Applications

Thermostat

DIP Switch Settings and On-Board Links (figure 42)
W914
W915
(Y1 to Y2)
(DS to R)
W951
DehumidifiDIP Switch 1
(O
to R)
Two-Stage
cation or
Heat
Pumps
Cooling
Harmony

Wiring Connections

III
'"
1Heat / 1 Cool

Intact

NOTE- Use DIP
switch 3 to set
second-stage
heat QN delay.
QFF-7 minutes.
0N-12 minutes.

1 Heat / 2 Cool

CONTROL
TERM. STRIP

OUTDOOR
UNIT

@
®

Cut

Intact

NOTE- Use DiP
switch 3 to set
second-stage
heat ON delay.
QFF- 7 minutes,
0N-12 minutes.

1 Heat / 2 Cool
with t'stat with
dehumidification
mode

S1
T'STAT

®
®

®
®
@

_,------Q
®

S1
T'STAT

CONTROL
TERM. STRIP

OUTDOOR
UNIT

Cut

NOTE- Use DIP
switch 3 to set
second-stage
heat ON delay.
QFF- 7 minutes,
0N-12 minutes.

Intact

®
@
@.

®
@@
@

$1
T'STAT

®
@
@

CONTROL
TERM. STRIP

OUTDOOR
UNIT

* "R" required on some units.

Page 29

@
@
(_

@---@
4_---@
@---@

TABLE 10
Field Wiring Applications

Thermostat

2 Heat / 2 Cool

(Continued)

DIP Switch Settings and On-Board Links (figure 42)
W914
W915
(DSto R)
W951
(Y1 to Y2)
DehumidifiDIP Switch 1
Two-Stage
(O
to R)
cation or
Cooling
Heat Pumps
Harmony
III"
OFF

Cut

Intact

Wiring Connections

$1
T'STAT

CONTROL
TERM. STRIP

OUTDOOR
UNIT

2 Heat / 2 Cool
with t'stat with
dehumidification mode

OFF

Cut

Intact

®
®
®
@

®®

@
@

$1
T'STAT

®
@
@

CONTROL
TERM. STRIP

OUTDOOR
UNIT

®
®.
®
®.

®
0----_

.@----@
@
2 Heat/1

Cool

OFF

Intact

$1
T'STAT

_----_
CONTROL
TERM. STRIP

OUTDOOR
UNIT

¢-

®.

®____.__
,:2)®
@
O@
@
* "R" required on some units.

Page 30

®
@

TABLE 10
Field Wiring Applications

Thermostat

Dual Fuel
Single Stage
Heat Pump

(Continued)

DIP Switch Settings and On-Board Link (figure 42)
W914
W915
(DS to R)
W951
Dehumidifi(Y1 to Y2)
DIP Switch
(o
to R)
cation or
Two-Stage
Heat Pumps
Cooling
Harmony
III ,r_
DIP Switch 1
OFF

Intact

Cut

Wiring Connections

L7724U
T'STAT

®
®

ComfortSense
7000 L7724U
thermostat w/
dual fuel capabilities
Capable of 2
stage gas heat
control

CONTROL
TERM. STRIP

HEAT PUMP

_)-

_.
@
® .....
®
@
®.

_.-o_
@
...,
®

67M41"

@
@
®

®
®

Flou,doo,

®
Dual Fuel
Two Stage
Heat Pump

DIP Switch 1
OFF

Cut

Intact

Cut

L7724U
T'STAT

®
®

ComfortSense
7000 L7724U
thermostat w/
dual fuel capabilities
Capable of 2
stage gas heat
control

defrost tempering kit 67M41

Page 31

CONTROL TERM.
STRIP

@
(:i:)
@
@

@
_
@

®.

.®

®
@

_).
4b

Sellso,

HEAT PUMP

Q
* Connect W1 to W1 QNLYifusing

®
67M41"

®
@
®
@
o.,b,.e
®
se"s°'U

TYPICAL G71MPP WIRING DIAGRAM

BLOWER

_7_ ........
F --- _ (_7

P_4
¸ i\J

.....

SPEE_

CHARI

WIRING

i0i551
PART
i_::

i36C-OS_
.......
60c:1!_o
NOTE,
SPECIFIC

S12_(2)

......

$47

B,--

F_A_E

IGNIT3R

IR331

$41

St28

INSTALLATION
SET

CORRECT

BLOWER

TONNAGE

BEING

tEMPERATURE

IYP!CAL
SYSTEM
SHOWN
WITH
A CONVENTIONAl

SECONDARY
LIMIT

A92

ROOM

COOLING

HEARING

INSTRUCTIONS

RISE

FOR
SPEED

FOR

LI3

FACTORY

APPLIED,
_
/_us£

FOR
2 NEAT/2
COOL
THERMOSTAT,
SEE

FIELD

CONTROL
INTEGRATED

T_ERNQSTAT

IaP

DEFAUI

ONLY
T IS

A 2

THEROOSTAT
SUPPLIED
COPPER

ACC

WIRE

,J_46

_RANSFDRNER
TI

INSTAl{AT[ON
10 DINER

INSTRUCTIONS
EQUIPNEN]
AN9

CONDUCTORS

A T_O
STAGE
THIS
FURNACE

THERMOSTAT
IN VARIABLE

SI13 IS USED
ON
135 UNITS
ONLY

FOR
CONNECTIONS
ACCESSORIES

ONLY

RUST
BE
CAPACITY

USED
_ITH
MODE

REFER
rB INSFALLATION
INSFRUCIIBNS
_OR
MORE
INFgRMAF[ON
ON RECaNMENDED
TYPES
THERMOSTATS
AND
SETTINGS
FOR
OPTIMA{

_D[SCHARGE
rERMINALS
_N_y
_24V

PO_ER

AN_
ARE

ii0, AND

090,

OUTDOOR
AIR
FOR
FUTURE
USE

PROVIDED

OPTIONAL
HUMI_IFIER
HEAT
DE_ANB

FOR
DURING

WARNING
ELECTRIC S_CK HAZARD,CAN CAUSE INJURY
_R DEAT_UNIr NUSF BE GROUNDED IN ACCORDANCE
WIT_ NATIONAL AN_ LOCAL CODES¸
....

_DENOTES

LINE
CLASS

VOLfAGE
FELD
INSTALLED
II VOLTAGE
FZEID
WIRING

OPTIONAL

IilO,ObO[lO%
135_000
1GO

USED

STAG{

DESIRED

fABLE

7O,O0O
24O
_TU_
RES_T
_70¸@¸¸¸¸¸5_

A
............................................................................................................................
iiii.........................................
i
siii il

$51

AND

HARNESS

PURPLE
COLOR
_A_

[iOiSGi-03
101551
_.LUE YELLOW
SE E

PROCEDURE
li

Oi
NO

NOIEIF ANY WIRE IN T_[S APPLIANCE ;S R_PLACED,IT
MUST BE REPLACED W!TH WIRE BF L_KE SIZE,
RAIING, INSULATION THICKNESS, AND TERMINATION¸

COMPONENTS

FIGURE 41

Page 32

INTEGRATED CONTROL

NEUTRAL
TERMINALS

COMBUSTION
AIR INDUCER
CONNECTOR

IGNITOR
CONNECTOR

DIAGNOSTIC
LINE VOLTAGE
TERMINALS

PUSH BUTTON_

DIP SWITCHES

OUTDOOR AIR_
SENSOR
_..
TERMINALS
(Future Use)

INDOOR
BLOWER
CONNECTOR

7-SEGMENT
DIAGNOSTIC LED

DISCHARGE AIR _
SENSOR
TERMINALS
(Future Use)

ON-BOARD
LINKS

FACTORY TEST
HEADER PINS.
FACTORY USE ONLY.

THERMOSTAT

1/4"QUICK

CONNECT

DS:
W2=
Wl=
R=
G=
C=

CONNECTIONS

(TB1)

DEHUMIDIFICATION SIGNAL
HEAT DEMANDFROM 2ND STAGE T'STAT
HEAT DEMANDFROM IST STAGE T'STAT
CLASS 2 VOLTAGE TO THERMOSTAT
MANUAL FAN FROM T'STAT
THERMOSTATSIGNAL GROUNDCONNECTEDTO TRANSFORMER
GROUND (TR) & CHASIS GROUND (GRD)
YI: THERMOSTAT Ist STAGE COOL SIGNAL
Y2: THERMOSTAT 2rid STAGE COOL SIGNAL
O: THERMOSTAT SIGNAL TO HEAT PUMP REVERSING VALVE
H= 24V HUMIDIFIER OUTPUT
L= LENNOX SYSTEM OPERATION MONITOR

TERMINALS

HUM : 120 VAC OUTPUT TO HUMIDIFIER
XMFR = 120 VAC OUTPUT TO TRANSFORMER
LI
= 120 VAC INPUT TO CONTROL
CIRC = 120 VAC OUTPUT TO CIRCULATING BLOWER
EAC = 120 VAC OUTPUT TO ELECTRONIC AIR CLEANER
NEUTRALS=120
VAC NEUTRAL

FIGURE 42

Page 33

TABLE 11
Thermostat Selection Switch Settings
Operation

Thermostat

Switch 1

Switch 2

Switch 3

Variable Capacity Heat
(40% to 100%)

Two-Stage

Off

Three-Stage Heat
(40%, 70%, 100%)

Single-Stage

Off

2nd stage delay
OFF = 7 minutes
ON = 12 minutes
3rd stage delay
10 minutes fixed

Two-Stage Heat (W1 70%, W2 100%)

Two-Stage

Off

off delay affects comfort and is adjustable to satisfy individ-

G71MPP units are equipped with a variable-capacity, vanable-speed integrated control. This control manages ignition timing, combustion air inducer speed, heating mode
fan off delays and indoor blower speeds based on selections made using the control DIP switches and on-board
links. The control includes an internal watchguard feature
which automatically resets the ignition control when it has
been locked out,
Heating Operation DIP Switch Settings -- Figure 42
Switch 1 -- Thermostat Selection -- This unit may be
used with either a single-stage or two-stage thermostat.
The thermostat selection is made using a DIP switch which
must be properly positioned for the particular application.
The DIP switch is factory-positioned for use with a twostage thermostat, If a single-stage thermostat is to be used,
the DIP switch must be repositioned, See table 11,

ual applications. Adjust the blower off delay to achieve a
supply air temperature between 90 ° and 110°F at the exact
moment that the blower is de-energized, Longer off delay
settings provide lower supply air temperatures; shorter settings provide higher supply air temperatures, Table 12 provides the blower off timings that will result from different
switch settings,
TABLE 12
Blower Off Delay Switch Settings
Blower Off Delay
(Seconds)
60
90

Switch 4

Switch 5

Off
Off

On
Off

120
180

On
On

Off
On

Switch 2 -- Operating Mode with Two-Stage Thermostat -- If a two-stage thermostat is used, the furnace can
operate in either variable-capacity or conventional twostage mode, When variable-capacity mode is selected, the
firing rate of the unit is varied to maximize comfort, Conventional two-stage mode is the factory default setting, See
table 11,

Indoor Blower Operation DIP Switch Settings
Switches 6 and 7 -- Continuous Indoor Fan OperationBlower Speed -- Switches 6 and 7 are used to select blower motor speeds during continuous indoor blower operation, The unit is shipped from the factory with the DIP
switches positioned for medium low (2) speed during continuous indoor blower operation, The table below provides

Switch 3 -- Second-Stage Heat On Delay -- If a singlestage thermostat is used, the integrated control can be
used to energize second-stage heat after either 7 minutes
or 12 minutes of first-stage heat operation, See table 11.

the continuous blower speeds that will result from different
switch settings, Refer to tables 21 through 31 for corresponding cfm values,
TABLE 13
Continuous Indoor Blower Operation -- Blower Speeds

Switches 4 and 5 -- Blower-Off Delay -- The blower-on
delay of 45 seconds is not adjustable. The blower-off delay
(time that the blower operates after the heating demand
has been satisfied) can be adjusted by moving switches 4
and 5 on the integrated control, The unit is shipped from the
factory with a blower-off delay of 90 seconds, The blower

Page 34

Speed
1 - Low
2 - Medium Low
(Factory)
3 - Medium High
4 - High

Switch 6
Off

Switch 7
On

Off

On
On

Off
On

Switches8

and 9 -- Cooling Mode Blower Speed -Switches 8 and 9 are used to select cooling blower motor
speed The unit is shipped from the factory with the DIP
switches positioned for high speed (4) indoor blower motor
operation during the cooling mode The table below pro-

Cooling

Ramping Option
A (Factory)
B
C
D

vides the cooling mode blower speeds that will result from
different switch settings Refer to tables 21 through 31 for
corresponding cfm values
TABLE 14
Cooling Mode Blower Speeds
Speed
1 - Low
2 - Medium Low

Switch
On
Off

3 - Medium High
4- High (Factory)

On
Off

With switches 10 and 11 set to ON, motor will bypass ramping profiles and all delays and will immediately run at selected COOLING speed upon a call for cool LED will continue to operate as normal This mode is used to check

Cooling

OFF

82% CFM
__
50%
CFM
1/2 MIN
i_

•

Switch 11
Off
Off

-10% (approx)
MOTOR TEST

Off
On

On
On

100%

--D,._

DEMAND

Once demand is met, motor ramps down to stop

(
OFF

82%CFM /
7 1/2 MIN
_
COOLING

TABLE 15
Mode Blower Speed Adjustment
Switch 10
On
Off

.__

Ramping Option B
Motor runs at 82% for approximately 7-1/2 minutes If
demand has not been satisfied after 7-1/2 minutes,
motor runs at 100% until demand is satisfied

•

,_p

Adjustment
+10% (approx)
NORMAL (Factory)

OFF

CFM

7 1/2 MIN
COOLING

OFF

motor operation

Switch 13
Off
Off
On
On

Ramping Option A (Factory Selection)
Motor runs at 50% for 30 seconds
Motor then runs at 82% for approximately 7-1/2 minutes
• If demand has not been satisfied after 7-1/2 minutes,
motor runs at 100% until demand is satisfied
• Once demand is met, motor runs at 50% for 30 seconds then ramps down to stop

Off
Off

plication Table 15 provides blower speed adjustments that
will result from different switch settings Refer to tables 21
through 31 for corresponding cfm values

Switch 12
Off
On
Off
On

•
•

Switch 9
On
On

Switches 10 and 11 -- Cooling Mode Blower Speed Adjustment -- Switches 10 and 11 are used to select blower
speed adjustment settings The unit is shipped from the
factory with the DIP switches positioned for NORMAL (no)
adjustment The DIP switches may be positioned to adjust
the blower speed by +10% or -10% to better suit the ap-

TABLE 16
Mode Blower Speed Ramping

DEMAND

100% CFM
--"IP"

•

Ramping Option C
Motor runs at 100% until demand is satisfied

•

Once demand is met, motor runs at 100% for 45 seconds then ramps down to stop

Switches 12 and 13 -- Cooling Mode Blower Speed
Ramping -- Switches 12 and 13 are used to select cooling
mode blower speed ramping options Blower speed ramping may be used to enhance dehumidification performance The switches are factory set at option A which has
the greatest effect on blower motor performance Table 16
provides the cooling mode blower speed ramping options
that will result from different switch settings The cooling

OFF

OFF
_._p--

lOO% CFM -DEMAND

Ramping Option D
• Motor runs at 100% until demand is satisfied
•

Once demand is met, motor ramps down to stop

mode blower speed ramping options are detailed below
NOTE - The off portion of the selected ramp profile only applies during heat pump operation in dual fuel applications

Page 35

COOLING
100% CFM
DEMAND

_OFF

Switches 14 through 19 -- Heating Mode Blower Speed
-- Switches 14 through 19 are used to select heating mode
blower motor speeds. These switches are factory set at the
OFF position which provides 100 % of normal speed during
HIGH HEAT demand, 70% of normal speed during MIDRANGE HEAT demand and 40% of normal speed during
LOW HEAT demand. Switches 14, 15 and 16 are used to
adjust the LOW HEAT blower motor speed, Switches 17,
18 and 19 are used to adjust the HIGH HEAT blower motor
speed, Table 17 provides the heating mode blower speeds
that will result from different switch settings. Refer to tables
21 through 31 for corresponding cfm values,
TABLE 17
Low Heat Blower Speeds
Thermostat
Demand

Low Heat
(Rto Wl)

Blower
Speed
Adjustments
+15%
+7.5%
Normal
-7.5%
-15%

DIP SWITCH SETTINGS
14

On
On

Off
Off

On
Off

Off
On

Off
Off

Blower
Speed
Adjustments

High Heat
(R to

+7.5%
Normal

w1 & w2)

-7.5%

+15%

-15%

Use the diagnostic push button to scroll through the menu
as described above. Release the button when the LED
flashes "-" to select the Field Test mode.
While in the Field Test mode the technician can:

DIP SWITCH SETTINGS
17

On
On

Off
Off

On
Off

Off
On
On

Off
Off
On

Diagnostic Push Button -- Figure 42
The diagnostic push button is located adjacent to the
seven-segment diagnostic LED. This button is used to enable the Error Code Recall mode and the Field Test mode.
Press the button and hold it to cycle through a menu of options, Every five seconds a new menu item will be displayed. When the button is released, the displayed item will
be selected. Once all items in the menu have been displayed, the menu resumes from the beginning until the button is released,
Error Code Recall Mode
Select "E" from the menu to access the most recent 10 error
codes. Select "c" from the Error Code Recall menu to clear
all error codes, Button must be pressed a second time
while "c" is flashing to confirm command to delete codes.
Press the button until a solid "---"is displayed to exit the Error
Code Recall mode,
Field Test Mode

TABLE 18
High Heat Blower Speeds
Thermostat
Demand

On-Board Link W915 -- Figure 42
On-board link W915 is a clippable connection between terminals Y1 and Y2 on the integrated control. W915 must be
cut if two-stage cooling will be used. If the link is not cut the
outdoor unit will operate in second-stage cooling only,
Diagnostic LED -- Figure 42
The seven-segment diagnostic LED displays operating
status, target airflow, error codes and other information,
The table on page 58 lists diagnostic LED codes,

• Initiate furnace ignition and move to and hold low-fire
rate by applying a R to W1 jumper.
• Initiate furnace ignition sequence and move to and
hold high-fire rate by applying a jumper from R to W1
and W2.

On-Board Link W914 -- Figure 42
On-board link W914, is a clippable connection between terminals DS and R on the integrated control. W914 must be
cut when the furnace is installed with either the Harmony
111
'" zone control or a thermostat which features humidity
control. If the link is left intact the PMW signal from the Harmony Iti control will be blocked and also lead to control
damage. Refer to table 19 for operation sequence in applications including G71MPP, a thermostat which features
humidity control and a single-speed outdoor unit. Table 20
gives the operation sequence in applications with a twospeed outdoor unit,
On-Board Link W951 -- Figure 42
On-board link W951 is a clippable connection between terminals R and O on the integrated control. W951 must be cut
when the furnace is installed in applications which include a
heat pump unit and a thermostat which features dual fuel
use, If the link is left intact, terminal "O" will remain energized eliminating the HEAT MODE in the heat pump,

• Initiate furnace ignition sequence and move to and
hold mid-fire rate by applying a jumper to R and W2.
• Apply then remove the jumper from R to W1 and W2 to
change the firing rate from low fire to mid fire and high
fire.
• A vent calibration sequence can be initiated even if a
thermostat signal is not present. Press and hold the
push button until a solid "C" is displayed. Release the
button and calibration will begin. The furnace will perform the high-fire and low-fire pressure switch calibrations and display "CAL". After calibration, the LED will
return to the flashing "-" display.
During Field Test mode operation, all safety switches are
still in the circuit (they are not by-passed) and indoor blower
performance and timings will match DIP switch selections.
Current furnace firing rate, indoor blower CFM and flame
signal will be displayed. To exit the Field Test mode, press
and hold the button. The menu will resume from the beginning. Also, cycle the main power to exit the Field Test
mode. The integrated control will automatically exit the
Field Test mode after 45 minutes of operation.

Page 36

G71MPP INTEGRATED

CONTROL CONFIGURATION

2NO STAGEHEAT ON DELAY
BIAGE 3 UPSTAGE
BEIAY ! MIN FIXED

SINGLE
SAGE ONIY
(TIME STA ING>
(S_ _ BN
ONLY)
407
7_% I087

GUIDE

CONTINUOUS
FAN MODEBLOWERSPEED

COOLING MODE BLOWER

SPEED

las4

HIGH
SPEED
MEDIUMoLOVsPEED(38X)
1

NFDIUMIIIGN
SPFED

LOW
SPEED
] NIN
UPSTAGE
DELAY

(28X)

MEDIUM HIGH

i a 3 ¢

_ m

MEDIUNLOV
SPEED

(70X>
SPEED

UPSTAGE
DEAY
_2
MN

LOW
SPEED
HIGH
(IOOX.)

ERROR
CODERECALL(SEECOL LIST FOR3 DIGITC_ES)
•
CYCLES
THROUGH
LASTi0 ERROR
CODES
(EXXXqIX_<)
•
TO CLEAR VH[LE IN ERROR
RECALL_
HOLDBUTTON
UNTIL SOLED
'E' IS _[SPLAYE_II{N RELEASE¸PRESSBUTTON
DURINGBLINKING'c" TO CONFIRM
_EETE ERRORCOL&
•
TO EXIT RECALL HOLDBUTTON
UNI_L ' E' [S DISPLAYED

2-STAGE EAT
(SV #1 O_

HOLD BUTTONUNTIL SOLID ' ' IS DISPLAYED
TEN RELEAS!
LOV FIRE JUMPERR TO VI J
HIGH FIRE JUMPERR TO WI & V2
MID FIRE JUMPERR TO V2 ONLY
(HT Z)
AXXX(CFN) FXXX (_A)
FLAME SIGNAL

70_,

SPEED ADJUSIMENI

NORMA

MODE

ONLY>

+ 107,

CONVENTIONAL
2STG
HEATING
MODE

_[AGNOSTICLED QUICKREFERENCE
[_LE' _LINKING 'O'
WARMUP:BLINKING"H"
hXX (INPUT%) P_

OOX

VARIABLE GAPAC
HEATING MODE

FELB TEST MOE CONTS
VENT CALIBRATION
HOL_ UNTIL SOL[_ "C" [S DISPLAYED
THENRELEASE
CAL VENT CALIBRATIONIN
TO

_ II
s

6 •

fox

(STG) #_U£EAXXXX
FAN=AXXX(CFM)

_
_

PREFERRED
MODE
(WB]]ULATION)
4OX TO
10% BASED UPQ
DMAND

VENT CALIBRATION:
CAL
(CFN)
SEE MANUALFOR COMPLETE
LEST

COOLING MODE BLOWER RAMPING

HEALING _LOWEN-OFF

DELAY
OPTION A

90 SECOND

2 s

OFF-SO%-8R%!0OX-5OX-OFF

OFF DEIAY
HID BLOWER
w i

60 SECOND
MIG DIOVER
OFF DFLAY

/ MODIFIED

NORMAL

HIGH

HEAl

SPEED

NORMAL
/ MODIFIED LOW HEAT SPEED
HEAT

CFM

HEAT SPEED
G Y2 YI C
NIGH

MODEIED

MODIFIEDLOW
HEAl SPEED
SEESV15,16
INCREASE/DECREASE
INCREASE/DECREASE

IOV

HEAT

SPEED

INCREASE LOW
HEAT SPEED
([OVER
OAT)
SE SV

I-STG COMPRESSOR

ND HARMONY
ZONING
OR

AIC UNIT

2 STAGE
COMPR
O0

HEAT SPEED
(!NCREASE
DAD
DECREASE H1Gil
SEE SV 19

i4
2-STO

CHANGE lOW

COMPRESSOR

HEAT

PUMP

UNIT

HEAT SPEED
R STAGE

CUT

CHANGEIOV
HEAT SPEEDBY
15X

CUT LINK

LINK

DEHUN
or
HARMONY
2°STAGE

CHANGE

HIGH

MEAT STPy.EED
BY
CHANGE HIGH

COMPRESSOR
LINK
(JUNFERS Y1 to YO)
WS_B
SEE IN EGRATED CONTROL _EIAILE9 SETUP IN BRMATON
£8R COMPLETE S_TUP & CONFIGURATIONPETAILS

HARMONY ZONING
OR

HEAT

SPEED

SIGNATURESTAT V/
DS CONNECTION

_CHANGE IoOV
HEAT SPEED BY
7Z

HEAT SPEE_

NOT CUT

]]ECREASF LOW
HEAl SPEED
( NCREAS ] !}AT)
SEE SW 16

HIGH

INCREASE HIGH
NEAT SPEED
(LOVER DAD
SEE sw 19

HEAT

PUMP

LINK

(JUMPERS R to 0)
v951

PRO £CI!VE PLASIIC[LM Q_,DIP S_ITCHES MAY BE
REMOVER FOR EASE IN SETTING BF DIP SV

FIGURE 43
Page 37

IEAT

(JUMPERS R to
W914

SPEED

CHANG]

DENUMIDIIICAFION
HARMONY lINK

NGN

DR)
CUI ON I_AR
INK (SBL_R IRACE)COMPLEE y IRU611
BgT lAYERS QN THE CONTRO BARD
LINKS CUT IN ERRUR INSIALL A JUMPER ON IHE AP_ROPRIAYE
IER_ NALS #N THE TERMI_,ALS{RIP

G71MPP,
OPERATING
SEQUENCE
System
Condition

TABLE 19
OPERATING
SEQUENCE
7000 Thermostat
and Single-Stage

ComfortSense"

Outdoor

Unit

s¥s T EM DEMAND

•
.
Thermostat
Step

Demand

I°1

Relative

Humidity
Compressor

Status

I
I

Blower
CFM
(COOL)

Comments

NO CALL FOR DEHUMIDIFICATION

Normal

Operation

Acceptable

24
VAC

High

100%

Compressor and indoor
blower follow thermostat
demand

BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation

Acceptable

24
VAC

High

Dehumidification
Call

Demand

0
VAC

High

7o%

1oo%

ComfortSense T`'7000
thermostat energizes Y1
and de-energizes D on a
call for de-humidification

PRECISION MODE (operates ind_ oendent of a Y1 thermostat demand)
Normal Operation

Acceptable

24
VAC

High

100%

Dehumidification
call

Demand

0
VAC

High

70%

Dehumidification
call ONLY

Demand

0
VAC

High

70%

On-board links at indoor unit with a single-stage outdoor unit:
With Condensing unit - Cut W914 (R to DS) on SureLight ® integrated control;
With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight ® integrated
control,

Page 38

Dehumidification mode
begins when humidity is
greater than set point
ComfortSense T`'7000
thermostat will keep outdoor unit energized after
cooling temperature setpoint has been reached in
order to maintain room
humidity setpoint.

TABLE 20
OPERATING SEQUENCE
G71MPP, ComfortSense '" 7000 Thermostat and Two-Stage Outdoor Unit
OPERATING
SEQUENCE

T
SXS EM DEMAND
Thermostat Demand

s s,e ste0ii

Condition

iii

On
On

W
1

"SYS'EM RESPONSE

Relative Humidity
W
2

Blower

Co 0 esso

Status

Acceptable

24
VAC

Low

70%

Acceptable

24
VAC

High

100%

Comments

(COOL)

NO CALL FOR DEHUMIDIFICATION
Normal Operation Y1

Normal Operation Y2

ROOM THERMOSTAT

Compressor and indoor
blower follow thermostat
demand

CALLS FOR FIRST STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation

Dehumidification
Call

Acceptable

24
VAC

Low

70%

Demand

0
VAC

High

70%

PRECISION MODE (operates independent
Normal Operation

Dehumidification
call

ComfortSense T_7000
thermostat energizes Y2
and de-energizes D on a
call for de-humidification

of a Y1 thermostat demand)

Acceptable

24
VAC

Low

70%

Demand

0
VAC

High

70%

Dehumidification mode
begins when humidity is
greater than set point
ComfortSense
thermostat

Dehumidification
call ONLY

Demand

0
VAC

High

70%

door unit energized
after
cooling temperature
set_oint has been reached
in order to maintain room
humidity

ROOM THERMOSTAT

T'_7000

will keep out-

setpoint.*

CALLS FOR FIRST AND SECOND STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation

Acceptable

Dehumidification
Call

Demand

PRECISION

MODE

(operates

Normal Operation

Dehumidification
call

Dehumidification
call ONLY

independent
On

of a Y1 thermostat

24
VAC

High

100%

0
VAC

High

70%

ComfortSense T_7000
thermostat energizes Y2
and de-energizes D on a
call for de-humidification

demand)

Acceptable

24
VAC

Low

70%

Demand

0
VAC

High

70%

Demand

0
VAC

High

70%

On-board links at indoor unit with a two-stage outdoor unit:
Cut factory link from Y1 to Y2 or cut W915 (Y1 to Y2) on SureLight ® integrated
control,
With Condensing unit - Cut W914 (R to DS) on SureLight ® integrated control;
With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight ®
integrated control,

Page 39

Dehumidification mode
begins when humidity is
greater than set point

ComfortSense T" 7000
thermostat will keep outdoor unit energized after
cooling temperature set3oint has been reached
in order to maintain room
humidity setpoint.

TABLE 21
G71MPP-36B-070 BLOWER PERFORMANCE (less filter)
0 through 0.80 in. w.g. External Static Pressure Range
HEATING BLOWER PERFORMANCE
Heating Input Ran e and Blower Volume - CFM
50%
60%
80%
9O%

Heating Adjust CFM Selections
Increase (+15%) Heat CFM

610

690

87O

975

Increase (+7.5%) Heat CFM

575

645

810

9O5

Default Heat CFM

545

610

76O

845

Decrease (-7.5%)

Heat CFM

Decrease (-15%)

Heat CFM

52o
iiiiiiiiiiiiiiiiiiiiiiiiiiiiii
490

58o
715
79O
!54o
! !ii! i! i! i! i! i! i!655i! i! i! i! 715
i! i! i! i! i! i! !i

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM

First Stage Cool Speed - cfm

Selections
Increase

(+10%) Cool CFM

Second Stage Cool Speed - cfm

Low

MediumLow

Medium
High

High
(Default)

Low

I MediumLow

I Medium
High

I (Default)
High

730

815

865

935

1015

1190

1280

1395

Default Cool CFM

880

755

795

855

930

1065

1155

1270

Decrease (-10%) Cool CFM

625

695

730

775

830

950

1010

1105

The effect of static pressure is included in air volumes shown.
Lennox Harmony Ill _ Zone Control Applications - Minimum blower speed is 250 cfm.
The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns).
With two-stage thermostat there are two modes available.
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 250 cfm,

G71MPP-36B-070
Blower Speed
Options I

BLOWER MOTOR WATTS - COOLING

First Stage
Motor Watts @ Various External 0Static
Pressures-in.
wg.
10.1010.2010.3010.4010.5010.6010.7010.80
[0.1010.2010.30ondS/ao.5010.6010.7010.8
osec
[ 0.40 tge

Increase (+10%) Cool CFM
Low

110

130

145

160

175

190

135

155

175

200

220

245

270

295

320

110

130

150

170

190

205

220

185

215

250

285

315

345

370

395

420

100
125

120
150

145
170

165
190

185
210

205
235

225
255

250
280

235
315

265
340

300
370

335
395

370
440

400
480

425
510

455
540

480
570

115

130

145

160

175

100

120

140

165

190

215

235

255

275

Medium-Low

110

130

145

165

180

200

140

165

190

220

245

265

290

315

340

Medium-High

Medium-Low

Medium-High
85
High 105
Default Cool CFM
Low

105

125

140

155

175

195

215

175

200

230

260

285

310

340

365

390

High
85
100
Decrease (-10%) Cool CFM

120

140

160

180

200

220

240

230

260

295

325

360

390

410

435

455

Low

100

120

130

145

160

110

125

150

175

190

210

225

Medium-Low

115

135

145

160

175

120

150

175

200

220

240

260

285

Medium-High
High

50
60

65
75

85
95

105
115

125
135

145
150

160
170

175
190

190
215

125
165

150
190

175
215

195
245

220
265

240
485

265
315

290
340

320
370

Page 40

TABLE 22
G71MPP-36C-090 BLOWER PERFORMANCE (less filter)
0 through 0.80 in. w.g. External Static Pressure Range
HEATING BLOWER PERFORMANCE
Heating Input Range and Blower Volume - CFM
50%
60%
80%
90%

Heating Adjust CFM Selections

740

1005

1100

Increase (+7.5%) Heat CFM

695

825

Default Heat CFM

655

725

870

950

Decrease (-7.5%)

Heat CFM

615

680

815

890

Decrease (-15%)

Heat CFM

Increase (+15%) Heat CFM

COOLING BLOWER

775

94o 1025

iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
575
630 i! !i!!i!!i!!i!!i!!i!!i!!i!!i!!i!!i!!i!!i!!i!!i!!i!i;
745
805

PERFORMANCE
Blower Speed Selections

Cooling Adjust
Selections

CFM
Low

Increase

(+10%) Cool CFM

First Stage Cool Speed - cfm
MediumMedium
High
Low
High
(Default)

Second Stage Cool Speed - cfm
MediumMedium
High
Low
Low
High
(Default)

705

790

845

920

1020

1185

1275

1395

Default Cool CFM

650

730

770

830

905

1060

1145

1270

Decrease (-10%) Cool CFM

600

670

705

750

800

925

1010

1100

The effect of static pressure is included in air volumes shown,
Lennox Harmony Ill " Zone Control Applications - Minimum blower speed is 250 cfm.
The following control configurations are available, See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns),
With two-stage thermostat there are two modes available.
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 250 cfm.

G71MPP-36C-090

BLOWER MOTOR WATTS - COOLING
Motor Watts @ Various External Static Pressures - in. wg.

Blower Speed

First Stage

Second Stage

Options
0 10.10
10.20
10.30
10.40
10.50
10.60
10.70
10.80
0 10.10
10.20
10.30
10.40
10.50
10.60
10.70
10.80

Increase (+10%) Cool CFM
Low

105

125

140

160

175

110

135

160

185

205

235

265

295

Medium-Low

100

125

150

170

185

205

125

155

185

220

245

275

305

330

360

Medium-High

110

135

160

180

200

220

165

195

230

265

300

330

355

380

410

High
65
Default Cool CFM

110

135

160

180

205

225

245

210

245

285

325

360

390

425

460

495

115

130

145

160

110

135

155

175

195

215

235

Medium-Low

110

130

150

165

185

105

125

145

170

200

225

250

270

295

Medium-High

Low

115

135

155

175

195

115

140

175

205

235

265

290

315

335

High
50
65
Decrease (-10%) Cool CFM

105

130

155

180

200

220

155

185

220

255

285

315

345

380

415

Low

105

120

135

150

105

125

150

170

190

210

Medium-Low

100

120

130

145

160

120

145

165

185

205

225

250

Medium-High
High

40
45

55
60

70
75

90
90

105
115

125
135

140
155

160
170

180
190

85
105

105
125

135
150

165
175

185
210

210
240

235
275

260
305

285
335

Page 41

Bottom

TABLE 23
G71MPP-60C-090 BLOWER PERFORMANCE (less filter)
Return Air, Return Air from Both Sides or Return Air from Bottom
0 through 0.80 in. w.g. External Static Pressure Range

and One Side

HEATING BLOWER PERFORMANCE
Heating

Heating Adjust CFM Selections

Input

50%

e and Blower Volume - CFM

Ran

80%

60%

90%

iiiiiiiiiiiiiii_i_;!i;ii:ii:i_:i_!_i!_!i!i_i_i_i_i_i_i_i_i_i_!_!_i_i_f_ii_
800
935
1205

Increase (+15%) Heat CFM

1335

Increase (+7.5%) Heat CFM

730

860

1110

1235

Default Heat CFM

715

820

1035

1150

Decrease (-7.5%)
Decrease (-15%)
COOLING

iiiiiiiiiiiiiiiiiiiii i i!iii ii!i!! ! !ii i

Heat CFM
Heat CFM

BLOWER

630

740

565

665

Adjust

CFM

First

Selections
Increase
Default
Decrease

(+10%)
Cool

Cool

CFM

CFM
Cool

CFM

Stage

Cool

MediumLow

Low

(-10%)

87O

97O

PERFORMANCE
Blower

Cooling

i i i i 96O
i i i ii i 1070
! ii!i !ii!ii! iii iiii i

Speed

Selections

- cfm

Medium
High

Second
High
(Default)

Low

Stage

I MediumLow

Cool
I

Speed

Medium
High

- cfm
I (Default)
High

1105

1185

1355

1545

1605

1710

1925

2165

995

1080

1205

1345

1440

1560

1755

1960

890

960

1090

1215

1275

1380

1590

1755

The effect of static pressure is included in air volumes shown.
Lennox Harmony Ill " Zone Control Applications - Minimum blower speed is 450 cfm,
The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns),
With two-stage thermostat there are two modes available,
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm.

G71MPP-60C-090 BLOWER MOTOR WATTS - COOLING
Bottom Return Air, Return Air from Both Sides or Return Air from Bottom and One Side
Blower Speed
Options I
Increase

First Stage
Motor Watts @ Various
10.1010.2010.3010.4010.5010.6010.7010.80

0
(+10%) Cool CFM
Low

External 0 Static
Pressures-in.
wg.
10.1010.2010.3oOndSa0.5010.6010.7010.80Sectge
10.40

115

135

160

185

205

230

255

275

300

305

340

375

410

440

475

505

535

565

Medium-Low

145

165

190

215

240

265

285

305

325

355

390

430

470

510

550

580

610

635

Medium-High

170

200

240

275

305

335

370

400

430

510

555

600

645

690

730

765

795

830

100

1031065

450

485

High

265295330365400435465500535725780835895935975

Default Cool CFM
Low

110

130

155

175

195

215

235

255

220

250

Medium-Low

110

130

Medium-High

145

165

285

320

350

385

415

155

180

200

220

245

265

285

270

190

215

245

270

295

320

340

390

305

345

385

420

455

485

515

545

425

465

500

540

580

610

640

High 180 205
Decrease (-10%) Cool CFM

240

270

300

330

365

395

430

670

540

580

625

670

710

755

795

830

870

Low

145

165

185

205

225

160

190

220

255

275

300

330

360

390

105

125

Medium-Low

100

120

140

165

190

210

225

245

195

225

260

295

325

350

385

415

450

Medium-High
High

110
155

130
175

160
195

185
220

205
245

225
270

250
295

275
315

300
340

295
400

330
435

365
470

400
510

430
545

460
585

495
610

535
640

570
665

Page 42

TABLE 24
G71MPP-60C-090 BLOWER PERFORMANCE (less filter) -- Single Side Return Air
(Air volumes in bold require field fabricated transition to accommodate 20 x 25 x 1 in. cleanable air filter
in order to maintain proper air velocity across the filter.)
0 through 0.80 in. w.g. External Static Pressure Range
HEATING BLOWER PERFORMANCE
Heating

Heating Adjust CFM Selections
Increase (+15%) Heat CFM

Input

50%

60%

790

920

Range

and Blower

Volume
80%

- CFM
90%

iiiiiiiiiiiiiiiiiiiil;!;i;!;;!_iii_!i_!!!!;!i!!i!!i!!i!i!i!i!i!i!i!i!i
1180
1310

Increase (+7.5%) Heat CFM
Default Heat CFM

725
850
1090
1205
iiiiiiii'ii'ii
¸!I
¸!I !i !ii!iiiiili!
!i !i675
!i !!
!i !i!! ii!i!ii790
i! i! i!iiiiii?!!i!
i!ii!iiiiiiiiiii!iiii
iii,i i 1015
!!i!i!!!iiiii!i!ii!iiiilililililililil
1125

Decrease (-7.5%)

Heat CFM

Decrease (-15%)

Heat CFM

625

730

iiiiiiiiiiiiiiiiiiiii__i_!i!__i__i_i_ii_i!i!__!!i!!i!!i!iii__i__i__i__i__i__i__i__i__i__i__
940
1045

565

665

iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii_______!!!!_!!_!!_!!_!!_!!_!!_!!_!!_!!_!!_!!_!!_!!_!!_!!_!__!
860
960

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM

First Stage Cool Speed - cfm

Selections

Second Stage Cool Speed - cfm

Low

MediumLow

Medium
High

High
(Default)

Low

MediumLow

Medium
High

High
(Default)

Increase (+10%) Cool CFM
Default Cool CFM

1080
985

1160
1060

1315
1185

1490
1330

1575
1405

1690
1530

1895
1735

2135
1935

Decrease (-10%) Cool CFM

865

930

1065

1185

1250

1355

1560

1735

The effect of static pressure is included in air volumes shown,
Lennox Harmony Ill " Zone Control Applications - Minimum blower speed is 450 cfm.
The following control configurations are available, See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns),
With two-stage thermostat there are two modes available.
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm.

G71MPP-60C-090

BLOWER

MOTOR

WATTS

- COOLING

Motor
Blower

Speed
Options

First
0

Watts

@ Various

External

Static

Pressures

- in. wg.

Stage

10.1010.2010.3010.4010.5010.6010.7010.800

Increase (+10%) Cool CFM
Low

{0.1010.2010.SoC°ndSlag_o{0.6010.7010.8010.40

565

Medium-Low

645

Medium-High

84O
105
0

High
Default Cool CFM
Low

46O

Medium-Low

53O

Medium-High

67O
865

High
Decrease (-10%) Cool CFM
Low

445

Medium-Low

510

Medium-High

635
765

High

Page 43

TABLE
G71MPP-60C-090

HEATING

BLOWER

Increase
Default
Decrease
Decrease

(+15%)

Heat

(+7.5%)
Heat

Heat

CFM
CFM

Heat CFM

(-15%)

Air Base

Heat

Input Ran e and Blower Volume - CFM
60%
80%
90%

Heating
50%

CFM

(-7.5%)

RAB Return

PERFORMANCE

Heating Adjust CFM Selections
Increase

PERFORMANCE
(less filter) -- Side Return Air with Optional
0 through
0.80 in. w.g. External
Static Pressure
Range

CFM

770

895

1155

1290

710

825

1070

1195

660

775

1005

1115

605

710

92O

1030

555

650

845

945

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM

First Stage Cool Speed - cfm

Selections
Increase

(+10%) Cool CFM

Second Stage Cool Speed - cfm

Low

MediumLow

Medium
High

High
(Default)

Low

I MediumLow

I Medium
High

I (Default)
High

1060

1135

1285

1455

1525

1655

1860

2100

Default Cool CFM

960

1035

1165

1310

1385

1500

1695

1905

Decrease (-10%) Cool CFM

865

920

1050

1165

1240

1320

1510

1695

The effect of static pressure is included in air volumes shown,
Lennox Harmony Ill _ Zone Control Applications - Minimum blower speed is 450 cfm,
The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns),
With two-stage thermostat there are two modes available,
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm.

G71MPP-60C-090 BLOWER MOTOR WATTS - COOLING
Side Return Air with Optional RAB Return Air Base
Blower Speed
Options I

First Stage
Motor Watts @ Various External 0 Static
Pressures-in.
wg.
10.1010.2010.3010.4010.5010.6010.7010.80
10.1010.2010.3oOndSa0.5010.6010.7010.80Sectge
I 0.40

0
Increase (+10%) Cool CFM
Low

110

130

150

175

195

215

240

265

290

275

305

340

380

410

440

470

505

540

Medium-Low

130

155

175

200

220

245

265

290

315

360

390

420

455

485

515

550

590

625

Medium-High

160

190

220

255

280

305

335

360

390

490

530

570

610

645

680

715

750

785

220

255

295

330

365

400

430

460

490

695

750

805

855

895

935

965

995

1025

High

Default Cool CFM
80

120

140

165

190

210

235

255

190

225

265

305

330

355

390

420

455

Medium-Low

Low

100

120

140

165

190

215

235

255

275

265

295

325

355

390

420

455

495

530

Medium-High

140

160

185

205

235

260

285

305

325

375

410

440

475

500

530

570

610

650

High 180 205
Decrease (-10%) Cool CFM

240

270

300

325

350

380

405

520

560

605

645

685

720

760

805

845

Low

105

125

140

160

180

200

220

155

175

200

225

255

290

315

340

365

Medium-Low

115

135

155

175

200

220

245

185

210

235

260

295

325

355

385

415

Medium-High
High

105
135

125
160

150
185

175
215

200
235

220
260

240
285

265
305

290
330

255
370

290
400

330
440

365
475

400
505

430
530

460
565

490
600

520
635

Page 44

Bottom

TABLE 26
G71 MPP-60C-110 BLOWER PERFORMAN CE (less filter)
Return Air, Return Air from Both Sides or Return Air from Bottom
0 through 0.80 in. w.g. External Static Pressure Range

and One Side

HEATING BLOWER PERFORMANCE
Heating Input Range and Blower Volume - CFM
50%
60%
80%
90%

Heating Adjust CFM Selections
Increase (+15%) Heat CFM

1050

1215

1535

1695

Increase (+7.5%) Heat CFM

975

1125

1430

1585

Default Heat CFM

96O

1075

1335

1480

Decrease (-7.5%)

Heat CFM

86O

99O

1250

1380

Decrease (-15%)

Heat CFM

79O

910

1145

1260

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM

First Stage Cool Speed - cfm

Selections
Increase

(+10%) Cool CFM

Second Stage Cool Speed - cfm

Low

MediumLow

Medium
High

High
(Default)

Low

MediumLow

Medium
High

High
(Default)

945

1020

1160

1300

1625

1745

1990

2210

Default Cool CFM

840

910

1055

1180

1465

1580

1790

1995

Decrease (-10%) Cool CFM

740

800

920

1045

1290

1405

1605

1790

The effect of static pressure is included in air volumes shown,
Lennox Harmony Ill _ Zone Control Applications - Minimum blower speed is 450 cfm,
The following control configurations are available, See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns),
With two-stage thermostat there are two modes available.
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only),
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DiP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm

G71MPP-60C-110 BLOWER MOTOR WATTS -COOLING
Bottom Return Air, Return Air from Both Sides or Return Air from Bottom
Motor Watts @ Various
First Stage

Blower Speed
Options

External

0 10.1010.2010.3010.4010.5010.6010.7010.80
Increase (+10%) Cool CFM
Low

and One Side
Static Pressures

- in. wg.

10.1010.2010.3oOndS/a0.5010.6010.7010.80sectge
10.40

115

135

160

180

200

220

240

280

315

350

390

430

475

510

550

585

Medium-Low

105

130

150

175

200

220

245

270

340

380

425

465

505

545

575

610

645

Medium-High

120

140

170

195

225

250

275

300

330

510

545

585

620

675

735

770

805

840

160

185

210

235

265

290

325

360

395

710

755

805

855

905

950

980

101

1035

110

135

155

175

195

215

205

235

275

310

345

380

415

450

485

105

125

150

170

190

215

235

250

285

325

360

400

440

470

505

540

Medium-High
95
115
High 125
150
Decrease (-10%) Cool CFM

135
175

160
200

190
225

220
255

240
280

265
305

285
335

375
510

410
550

445
595

485
640

530
685

575
725

605
770

635
815

670
860

Low

100

115

125

145

160

180

155

180

210

240

270

295

325

355

385

High
Default Cool CFM
Low
Medium-Low

Medium-Low

105

125

150

165

185

200

185

215

245

280

315

345

380

415

450

Medium-High
High

70
95

85
110

105
135

125
160

150
190

170
220

195
240

215
260

235
280

265
375

300
415

345
455

385
495

425
535

465
575

500
615

535
650

570
690

Page 45

TABLE 27
G71MPP-60C-110 BLOWER PERFORMANCE (less filter) -- Single Side Return Air
(Air volumes in bold require field fabricated transition to accommodate 20 x 25 x 1 in. cleanable air filter
in order to maintain proper air velocity across the filter.)
0 through 0.80 in. w.g. External Static Pressure Range
HEATING BLOWER PERFORMANCE
Heating Input Ran e and Blower Volume - CFM
50%
60%
80%
90%

Heating Adjust CFM Selections

1030

Increase (+15%) Heat CFM

Decrease (-7.5%)

1185

iiiiiiiiiiiiiiiiiiiiii;_i!_i_i_!i_!i_!i_!i_!i_!i_!_!_!_!_!_!_!_!_!_i
I
1490
1630

i!ijjjj !!i!i!i iiiii!i955
i!!i!!i!ii lO95
!ii iiiii i!i ililililililililiiiiiiiiiiill
1380

Increase (+7.5%) Heat CFM
Default Heat CFM

1525

iiiiiiii'ii
¸!i!i!i i!i i!iiiiiii!
i i i i !!i!!i!!i!!i!!i!!i!!i!!i!!i!!ii!i!ii!!ii!iiiiliiiii
!! !! !i
¸!I
¸!tiiii i!iiiiiiiili!
ii ! iiii!ii!ii
!!
1305
1435 iill iiiiiiiii'ii
iiiiiiiiiiiiiiiiiii i i! i!

Heat CFM

ii!

i!i!i!i!i!i!i!i!i!i!i!i!i!i!iiii
840
765

Decrease (-15%) Heat CFM

965
880

!i i

!i!i!i!i!i!i!i!i!i!i!iiiiiii!i i!

1210
1330
iiiiiiiiiiiiiiiiiiiiiiiii_:iii_19_5_!i_!i_!i_!i_!i_!i_!i_!i_!i_!i_!i_!_!i!!!_!_
1110
1225
......................................................

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM

First Stage Cool Speed - cfm

Second Stage Cool Speed - cfm

Selections

Low

MediumLow

Medium
High

High
(Default)

Low

I MediumLow

I Medium
High

I (Default)
High

Increase (+10%) Cool CFM
Default Cool CFM

935
840

1025
915

1155
1050

1285
1175

1585
1435

1700
1535

1905
1740

2135
1930

Decrease (-10%) Cool CFM

750

800

925

1050

1280

1385

1570

1755

The effect of static pressure is included in air volumes shown,
Lennox Harmony Ill" Zone Control Applications - Minimum blower speed is 450 cfm,
The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns).
With two-stage thermostat there are two modes available.
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm.

G71 MPP-60C-110

BLOWER

MOTOR WATTS - COOLING

Blower Speed

First Stage
Second Stage
Motor Watts @ Various External Static Pressures - in. wg.

o tions0 I0.10
I0.20
I0.30
I0. I00.50
I0.80
I0.70
I0.800 I0.10
I0.20
I0.30
I0. I00.50
I0.80
I0.70
I0.80
I

Increase (+10%) Cool CFM
Low
Medium-Low

110

130

105

125

150

135
175

160
195

185
220

Medium-High
115
High 155
Default Cool CFM
Low
Medium-Low

150

165

185

210

230

255

295

345

390

430

470

510

545

585

170

190

215

235

255

340

375

415

455

490

525

570

615

660

210
250

230
285

255
310

285
335

310
360

455
650

500
710

555
770

610
835

655
880

695
920

750
960

800
995

850
1035

110

125

145

165

185

205

195

230

270

305

345

380

415

455

490

105

125

140

160

180

200

220

225

265

315

360

400

440

475

515

555

130
165

150
190

175
215

200
235

225
260

245
285

265
310

365
495

400
535

445
580

485
625

525
675

565
725

610
770

650
815

690
860

Medium-High
95
110
High 115 135
Decrease (-10%) Cool CFM
Low

4OO

Medium-Low

455

Medium-High

57O
69O

High

Page 46

G71MPP-60C-110
HEATING

BLOWER

TABLE 28
BLOWER PERFORMANCE (less filter) -- Side Return Air with Optional RAB Return Air Base
0 through 0.80 in. w.g. External Static Pressure Range

PERFORMANCE

Heating Input Range and Blower Volume - CFM
60%
80%
90%

Heating Adjust CFM Selections

50%

Increase (+15%) Heat CFM

1020

1175

1485

1635

Increase (+7.5%) Heat CFM

950

1095

1385

1535

Default Heat CFM

895

1030

1300

1435

Decrease (-7.5%)

Heat CFM

835

96O

1210

1335

Decrease (-15%)

Heat CFM

765

88O

1110

1220

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM
Selections
Low
Increase

(+10%) Cool CFM

First Stage Cool Speed - cfm
MediumMedium
High
Low
High
(Default)

Second Stage Cool Speed - cfm
MediumMedium
High
Low
Low
High
(Default)

1085

1155

1310

1475

1555

1685

1895

2130

Default Cool CFM

955

1050

1185

1335

1415

1540

1735

1930

Decrease (-10%) Cool CFM

850

920

1070

1195

1245

1350

1545

1725

The effect of static pressure is included in air volumes shown,
Lennox Harmony Ill _' Zone Control Applications - Minimum blower speed is 450 cfm.
The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns).
With two-stage thermostat there are two modes available.
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm.

G71MPP-60C-110

BLOWER MOTOR WATTS - COOLING

- Side Return Air with Optional RAB Return Air Base

Motor Watts @ Various External Static Pressures - in. wg.
First Stage
Second Stage

Blower Speed

Options
0 10.1010.2010.3010.4010.5010.8010.7010.80
0 1010102010301040105010801

Increase (+10%) Cool CFM
Low

105

125

150

175

200

220

245

265

290

250

285

320

360

395

435

470

500

535

Medium-Low

130

150

175

200

220

240

270

295

320

335

365

405

445

480

515

550

590

630

Medium-High

165

190

220

250

275

305

335

370

400

470

505

545

585

630

670

710

755

800

High 205
Default Cool CFM

240

285

330

360

390

420

450

485

655

695

745

790

840

885

925

965

1005

115

135

160

185

205

225

250

190

220

255

290

325

360

395

430

460

Medium-Low

100

120

145

165

185

205

230

255

280

250

285

325

360

390

420

455

485

520

Medium-High

135

Low

155

175

200

230

260

280

305

330

355

395

435

475

510

545

580

620

660

High 170 195
Decrease (-10%) Cool CFM

225

255

290

320

350

375

405

475

515

565

610

655

705

745

785

825

Low

110

135

155

175

195

220

150

170

200

225

255

285

315

340

370

Medium-Low

105

130

150

170

195

215

240

165

195

230

265

300

330

360

390

420

Medium-High
High

100
140

125
160

150
180

180
200

200
230

220
260

240
285

260
305

280
330

240
350

280
385

320
420

360
455

400
500

435
540

470
575

505
610

540
645

Page 47

Bottom

TABLE 29
G71MPP-60D-135 BLOWER PERFORMANCE (less filter)
Return Air, Return Air from Both Sides or Return Air from Bottom
0 through 0.80 in. w.g. External Static Pressure Range

and One Side

HEATING BLOWER PERFORMANCE
Input Ran e and Blower Volume - CFM
60%
80%
90%

Heating
50%

Heating Adjust CFM Selections
Increase (+15%) Heat CFM

1220

1390

1725

1885

Increase (+7.5%) Heat CFM

1130

1290

1600

1750

Default Heat CFM

1045

1195

1495

1650

Decrease (-7.5%)

Heat CFM

975

1110

1390

1535

Decrease (-15%)

Heat CFM

890

1020

1275

1405

COOLING

BLOWER

PERFORMANCE
Blower

Cooling

Adjust

CFM

First Stage

Selections
Increase

Cool

Decrease

Cool

CFM

(-10%)

Cool

CFM

Speed

MediumLow

Low

(+10%)

Default

Cool

Speed

Selections

- cfm

Medium
High

Second
High
(Default)

Low

Stage

I MediumLow
i
1730

Cool Speed
I
i

Medium
High
1945

- cfm
I
High
(Default)
i
2190

1135

1205

1365

1540

1615

1025

1105

1235

1390

1455

1580

1780

1985

915

985

1115

1235

1305

1400

1600

1780

The effect of static pressure is included in air volumes shown.
Lennox Harmony Ill _ Zone Control Applications - Minimum blower speed is 450 cfm.
The following control configurations are available. See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns),
With two-stage thermostat there are two modes available,
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only).
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm.

G71 MPP-60D-135
Bottom

Blower

Return

BLOWER
Air, Return

Speed

MOTOR
Air from

WATTS
Both

- COOLING

Sides

or Return

First Stage
Motor Watts

Air from

Bottom

and

One Side

Second
Stage
Pressures-in.
wg.

Options
0 10.10
10.20
10.30
10.40
10.50
10.60
10.70
10.80
0 10.1010.2010.3010.4010.5010.6
I

Increase

(+10%)

Cool

@ Various

External

Static

CFM

515

Low
Medium-Low

6O5

Medium-High

75O
98O

High
Default

Cool

CFM

43O

Low
Medium-Low

5OO

Medium-High

625
775

High
Decrease

(-10%)

Cool

CFM

355

Low
Medium-Low

415

Medium-High

515
610

High

Page 48

TABLE 30
G71MPP-60D-135 BLOWER PERFORMANCE (less filter) -- Single Side Return Air
(Air volumes in bold require field fabricated transition to accommodate 20 x 25 x 1 in. cleanable air filter
in order to maintain proper air velocity across the filter.)
0 through 0.80 in. w.g. External Static Pressure Range
HEATING BLOWER PERFORMANCE
Heating Input Range and Blower Volume - CFM
50%
60%
80%
90%

Heating Adjust CFM Selections
Increase (+15%) Heat CFM

1160

1325

1640

1790

Increase (+7.5%) Heat CFM
Default Heat CFM

1075

1225

1520

1670

1005

1145

1425

1570

Decrease (-7.5%)

Heat CFM

93O

1060

1325

1470

Decrease (-15%)

Heat CFM

85O

970

1215

1345

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM

First Stage Cool Speed - cfm

Selections

Second Stage Cool Speed - cfm

Low

MediumLow

Medium
High

High
(Default)

Low

MediumLow

Medium
High

High
(Default)

Increase (+10%) Cool CFM
Default Cool CFM

1105
990

1180
1075

1330
1210

1500
1355

1585
1430

1705
1545

1905
1765

2130
1975

Decrease (-10%) Cool CFM

890

950

1085

1210

1275

1370

1565

1755

G71MPP-60D-135

BLOWER MOTOR WATTS - COOLING
Motor Watts @ Various External Static Pressures - in. wg.
First Stage

Blower Speed
Options

0 10.1010.2010.3010.4010.5010.6010.7010.80
Increase (+10%) Cool CFM
Low

10.1010.2010.3oOndS/a0.5010.6010.7010.80Sectge
I 0.40

110

140

170

195

220

240

265

290

230

265

310

355

390

425

460

490

525

105

130

165

195

215

235

260

290

315

285

330

380

430

455

485

525

565

605

Medium-High
150
High 195
Default Cool CFM

175
230

205
270

235
305

270
340

300
375

330
410

360
445

385
480

425
605

465
650

515
695

560
740

605
800

645
855

685
900

730
945

770
985

Medium-Low

455

Low

Medium-Low

5O5

Medium-High

645
810

High
Decrease (-10%) Cool CFM
Low

36O

Medium-Low

42O

Medium-High

510
635

High

Page 49

G71MPP-60D-135

TABLE 31
BLOWER PERFORMANCE (less filter) -- Side Return Air with Optional RAB Return Air Base
0 through 0.80 in. w.g. External Static Pressure Range

HEATING BLOWER PERFORMANCE
Heating Input Ran e and Blower Volume - CFM
50%
60%
8O%
90%

Heating Adjust CFM Selections
Increase (+15%) Heat CFM

1180

1340

1650

1800

Increase (+7.5%) Heat CFM

1095

1245

1535

1680

Default Heat CFM

1020

1160

1435

1575

iii i ; iii i!!!!!!!!!i!i!

Decrease (-7.5%)

Heat CFM

945

1075

1335

1475

Decrease (-15%)

Heat CFM

870

990

1230

1350

COOLING BLOWER PERFORMANCE
Blower Speed Selections
Cooling Adjust CFM

First Stage Cool Speed - cfm

Selections

Second Stage Cool Speed - cfm

Low

MediumLow

Medium
High

High
(Default)

Low

1080

1155

1310

1480

1550

1660

1875

2105

Default Cool CFM

985

1055

1190

1325

1400

1510

1720

1920

Decrease (-10%) Cool CFM

875

945

1060

1190

1250

1345

1530

1715

Increase

(+10%) Cool CFM

I MediumLow

I Medium
High

I (Default)
High

The effect of static pressure is included in air volumes shown,
Lennox Harmony Ill _' Zone Control Applications - Minimum blower speed is 450 cfm,
The following control configurations are available, See Installation Instructions for details and DIP switch settings.
Heat Mode (Heating Blower Performance Table):
With a single-stage thermostat, furnace will operate at three, staged rates (40/70/100%) with a time delay between each stage (values in grey-shaded
columns),
With two-stage thermostat there are two modes available,
Traditional two-stage mode - W1 demand results in 70% firing rate. W2 results in 100% firing rate. No delay between stages. (values shown in 70%
and 100% grey-shaded columns only),
Variable Rate Capacity Mode - furnace automatically adjusts firing rate based on first- and second-stage cycle times. (all columns)
Cool Mode (Cooling Blower Perfomance table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28%, 38%, 70% and 100% (DIP switch selectable) of the same second-stage COOL speed position
minimum 450 cfm.

G71MPP-60D-135

BLOWER MOTOR WATTS - COOLING - Side Return Air with Optional RAB Return Air Base

Blower Speed
Options I

First Stage
Motor Watts @ Various External 0Static
Pressures-in.
wg. tge
10.1010.2010.30ond
osec
0 10.1010.2010.3010.4010.5010.6010.7010.80
10.40S/ao.5010.6010.7010.8
Increase (+10%) Cool CFM
Low

110

140

165

190

210

235

260

285

235

265

305

340

380

415

450

480

515

Medium-Low

105

130

160

190

210

230

255

285

310

290

325

370

410

450

490

515

545

575

Medium-High

145

170

205

235

265

290

325

355

390

420

460

510

555

595

640

680

715

755

High 200
Default Cool CFM

230

270

305

345

385

415

445

480

580

630

690

745

800

850

895

935

975

115

140

165

190

210

230

250

170

200

235

270

305

335

370

400

430

Medium-Low

105

125

150

175

200

225

250

270

200

230

270

310

355

400

435

465

495

Medium-High

115

Low

140

170

195

225

250

275

300

325

330

365

400

440

485

525

555

585

615

High 145
175
Decrease (-10%) Cool CFM

205

240

270

295

330

365

395

435

480

530

580

625

675

715

750

790

Low

115

135

155

175

195

215

135

155

180

205

240

280

305

330

355

Medium-Low

110

130

150

170

195

215

235

160

185

215

240

275

310

345

375

410

Medium-High
High

85
120

105
140

130
170

155
195

180
220

205
240

230
270

250
295

270
325

220
330

255
365

295
400

335
440

370
480

410
525

440
555

475
585

510
615

Page 50

FORYOURSAFETYREADBEFOREOPERATING

,&,WARNING

BEFORE BEFORE PLACING THE UNIT INTO OPERATION, smell all around the furnace 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 G71MPP is equipped with a gas control switch. Use only your hand to move the control switch,
Never use tools. If the switch will not move by hand, do not
try to repair it, Call a licensed professional service technician (or equivalent), Force or attempted repair may result in
a fire or explosion,
Placing the furnace into operation:
G71MPP units are equipped with an automatic ignition system. Do not attempt to manually light burners on this furnace. 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 this ignition system,

,AWARNING

-&WARNING

Gas Valve Operation (Figure 44)
1 - STOP! Read the safety information at the beginning of
this section.

A, CAUTION

2 - Set the thermostat to the lowest setting,
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,
5 - Remove the upper access panel.

-&WARNING

6 - Move the gas valve switch to the OFF position, See figure 44,

Priming

Condensate

Trap

The condensate trap should be primed with water prior to
start-up to ensure proper condensate drainage. Either pour
10 fl, oz. (300 ml) of water into the trap, or follow these steps
to prime the trap:
1 - Follow the lighting instructions to place the unit into operation,

7 - Wait five minutes to clear out any gas. tf 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.
8 - Move gas valve switch to the ON position, See figure
44, Do not force,
GAS VALVE
NEGATIVE AIR
PRESSURE PORT

POSITIVE AIR
PRESSURE PORT

MANIFOLD
PRESSURE TAP

2 - Set the thermostat to initiate a heating demand,
3 - Allow the burners to fire for approximately 3 minutes,
4-

Adjust the thermostat
mand,

to deactivate the heating de-

5 - Wait for the combustion air inducer to stop, Set the
thermostat to initiate a heating demand and again allow the burners to fire for approximately 3 minutes.
6-

Adjust the thermostat to deactivate the heating demand and again wait for the combustion air inducer to
stop. At this point, the trap should be primed with sufficient water to ensure proper condensate drain operation,

Page 51

INLET

SUPPLY
PRESSURE

OUTLET

_
TAP

GAS VALVE

SHOWN IN OFF POSITION

FIGURE 44

9 - Replace
theupperaccesspanel,
10- Turnonallelectricalpowertototheunit,
11- Setthethermostat
to desiredsetting,

1 - Operate unit at least 15 minutes before checking gas
flow. Determine the time in seconds for one revolutions of gas through the meter,

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.
Turning Off Gas to Unit
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 - Move the gas valve switch to the OFF position.
5 - Replace the upper access panel,

2 - Compare the number of seconds and the gas meter
size in table 32 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,

Gas Flow (Approximate)
TABLE 32
Gas Flow Rate (Ft._/Hr.)
Gas Meter Size
Seconds for 1
Revolution
1/2 cu ft Dial
1 cu ft Dial
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
30
60
120
32
56
113
34
53
106
36
50
100
38
47
95
40
45
90
42
43
86
44
41
82
46
39
78
48
38
75
50
36
72
52
35
69
54
33
67
56
32
64
58
31
62
60
30
60

3 - Remove temporary gas meter if installed,
NOTE - To obtain accurate reading, shut off all other gas
appliances connected to meter.
Manifold Pressure Measurement
To correctly measure
pressure between the
tive burner box must
adapter kit (available
measurement.

manifold pressure, the differential
positive gas manifold and the negabe considered, Use pressure test
as Lennox part 10L34) to assist in

1 - Connect test gauge "+" connection to manifold pressure tap on gas valve,
2 - Tee into the gas valve regulator vent hose and connect test gauge "-" connection,
3 - Start unit on low heat (40% rate) and allow 5 minutes
for unit to reach steady state,
4 - While waiting for the unit to stabilize, notice the flame.
Flame should be stable and should not lift from burner,
Natural gas should burn blue,
5- After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in table
33.
6 - Repeat steps 3, 4 and 5 on high heat,
NOTE- Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to replace
oressure tap plug.

A, CAUTION

Page 52

sure switch requirements and manifold pressures at all altitudes.
NOTE - In Canada, certification for installations at elevations over 4500 feet (1372 m) is the jurisdiction of local authorities.
G71MPP units require no manifold pressure adjustments
for operation at altitudes up to 10,000 feet (3048m) above
sea level. Units installed at altitude of 7,501 to 10,000 feet
(2287 to 3048m) require a pressure switch change per
table 33. Table 33 lists conversion kit requirements pres-

Conversion

Model
Input
Size

LP/Propane
Kit
0 - 10,000
(0 - 3048 m)

-O7O

-135

NOTE - A natural to L.P. propane gas changeover kit is
necessary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.

7,501 - 10,000
(2287 3048rn)

Manifold Pressure at All Altitudes
Low Fire
(40% rate)
Natural Gas

(in. w.g.)
High Fire
(100% rate)

LP/Propane

Natural

Gas

LP/Propane

36W77

-090
-110

The combustion air pressure switch is factory-set and requires no adjustment,

TABLE 33
Kit Requirements and Manifold Test Pressures

High Altitude Pressure
Switch Kit
0 - 7,500
(0 - 2286 m)

NOTE- The values given in table are measurements only.
The gas valve should not be adjusted.

40W05
33W41

Not required

40W06

0.7

2.0

3.5

10.0

40W07

NOTE - Pressure switch is factory set. No adjustment necessary.
NOTE - See previous page for manifold pressure measurement

All models use the factory installed pressure switch from 0-7,500 feet (0- 2286m).
procedure.

Page 53

2 - Check for the correct voltage at the furnace (furnace
operating).
Primary and Secondary

3 - Check amp-draw on the blower motor.
Motor Nameplate
Actual

Limits

The primary limit is located on the heating compartment
vestibule panel, The secondary limits 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

NOTE - Do not secure the electrical conduit directly to the
air ducts or structure,
Electronic

The 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. This type of lockout is usually due to low gas line
pressure, 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,
Exhaust and Air Intake Pipe
1 - Check exhaust and air intake connections for tightness
and to make sure there is no blockage,

(Two)

These manually reset switches are located on the burner
box, If tripped, check for adequate combustion air before
resetting,
Pressure Switches

(Three)

The pressure switches are located in the heating compartment on the combustion air inducer, These switches check
for proper combustion air inducer operation before allowing ignition trial, The switches are factory-set and require
no adjustment,
Back-Up Secondary

Limit (090, 110 and 135)

The back-up secondary limit is located on the combustion
air inducer. This switch protects the plastic components
from overheating due to indoor blower motor failure, If
tripped, check for proper blower operation before resetting,
Temperature

After the furnace has been started and supply and return
air temperatures have been allowed to stabilize, check the
temperature rise with the unit operating at 100 percent firing rate. 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 adjust the temperature rise
may cause erratic limit operation.

1 - Is the thermostat calling for heat?
2 - Are access panels securely in place?
3 - Is the main disconnect switch closed?
4 - Is there a blown fuse?
5 - Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6 - Is gas turned on at the meter?
7 - Is the manual main shut-off valve open?

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.

1 - Check all wiring for loose connections,

2- Are pressure switches closed? Obstructed exhaust
pipe will cause unit to shut off at pressure switches,
Check termination for blockages,
3- Reset manual flame rollout switches on burner box
cover.
Failure To Operate
If the unit fails to operate, check the following:

Rise

Electrical

Ignition

8 - Is the internal manual shut-off valve open?
9 - Is the unit ignition system in lock out? If the unit locks
out again, call the service technician to inspect the unit
for blockages.
10 - Is blower harness connected to ignition control? Furnace will not operate unless harness is connected.

Page 54

Theintegratedcontrolinitiatesa pressureswitchcalibrationattheinitialunitstart-upona callforheat.Theignition
controlwillalsoinitiatea calibration
anytimemainpoweris
turnedoffandbackonanda heatingdemandis present.
Additionalcalibrations
maybeinitiatedbytheservicetechnicianduringfieldtestsequence.
Thefollowingheatingsequenceof operation
assumescompletion
ofa successful
calibration.
NOTE - The thermostat selection DIP switch on the integrated control is factory-set in the "TWO-S TAGE" position.
Applications
Using a Two-Stage Thermostat
A - Heating Sequence -- Control Thermostat Selection
DIP switch in "Two-Stage"
Position (Factory Setting)
1 - On a call for heat, thermostat first-stage contacts close
sending a signal to the integrated control. The integrated control runs a self-diagnostic program and
checks high temperature limit switches for normally
closed contacts and pressure switches for normally
open contacts.The combustion air inducer is energized at ignition speed, which is approximately the
same as the inducer speed at 70 percent firing rate.
2-

Once the control receives a signal that the low-fire
pressure switch has closed, the combustion air inducer begins a 15-second pre-purge in the ignition speed.
3 - After the pre-purge is complete, a 20-second initial ignitor warm-up period begins. The combustion air inducer continues to operate at the ignition speed.

4 - After the 20-second warm-up period has ended, the
gas valve is energized and ignition occurs. At the
same time, the control module sends a signal to begin
an indoor blower 45-second ON-delay. When the
delay ends, the indoor blower motor is energized at a
speed that matches the firing rate. After the 10-second
ignition stabilization delay expires, the inducer speed
is adjusted to the appropriate target rate. The inducer
will remain at the 70 percent speed as long as the thermostat has a first-stage heating demand.
5 - If second-stage heat is required, the thermostat second-stage heat contacts close and send a signal to the
integrated control. The integrated control initiates a
30-second second-stage recognition delay.
6 - At the end of the recognition delay and on all subsequent calls for heat in the same heating cycle, the integrated control energizes the combustion air inducer at
high speed. The control also checks the high-fire pressure switch to make sure it is closed. As the inducer
speed is increased to high, the indoor blower motor is
adjusted to a speed which is appropriate for the target
rate.
7 - When the demand for high-fire (second stage) heat is
satisfied, the gas valve is de-energized and the fieldselected indoor blower off delay begins. The combustion air inducer begins a 20-second post-purge period.

Page 55

8 - When the combustion air post-purge period is complete, the inducer is de-energized. The indoor blower
is de-energized at the end of the off delay.
Applications

Using a Two-Stage

Thermostat

B - Heating Sequence -- Control Thermostat
DIP switch in "Variable Capacity" Position

Selection

1 - On a call for heat, thermostat first-stage contacts close
sending a signal to the integrated control. The integrated control runs a self-diagnostic program and
checks high temperature limit switches for normally
closed contacts and pressure switches for normally
open contacts.The combustion air inducer is energized at ignition speed, which is approximately the
same as the inducer speed at 70 percent firing rate.
2 - Once the control receives a signal that the low-fire
pressure switch has closed, the combustion air inducer begins a 15-second pre-purge in low speed.
3 - After the pre-purge is complete, a 20-second initial ignitor warm-up period begins. The combustion air inducer continues to operate at the ignition speed.
4 - After the 20-second warm-up period has ended, the
gas valve is energized and ignition occurs. At the
same time, the control module begins an indoor blower 45-second ON-delay. When the delay ends, the indoor blower motor is energized at a speed that
matches the firing rate. After the 10-second ignition
stabilization delay expires, the inducer speed is adjusted to the appropriate target rate. If the furnace is
operating in the initial heating cycle after power-up,
the initial firing rate will be approximately 40 percent.
The firing rate on subsequent cycles will be automatically adjusted by the integrated control based on thermostat cycles. The firing rate will vary and will range
from 40 percent to 90 percent. The furnace will continue this operation as long as the thermostat has a firststage heating demand.
5 - If second-stage heat is required, the thermostat second-stage heat contacts close and send a signal to the
integrated control. The integrated control either increases the firing rate to 70 percent (if the current rate
is at or below 60 percent) or increases the firing rate
by 10 percent (if the current rate is above 60 percent).
If the call for heat continues 5 minutes beyond this initial upstage, the rate will be increased by 10 percent
every 5 minutes until the call for heat is satisfied or the
furnace reaches 100 percent rate. As the firing rate increases, the indoor blower motor is adjusted to a
speed which is appropriate for the target rate.
6-

If second-stage heat demand is satisfied, but first
stage is still present, the furnace will continue to operate at the present firing rate until the heat cycle ends.

7 - When the demand for first- and second-stage heat is
satisfied, the gas valve is de-energized and the fieldselected indoor blower off delay begins. The combustion air inducer begins a 20-second post-purge period.

8 - Whenthecombustion
air post-purge
periodis complete,theinduceris de-energized.
Theindoorblower
is de-energized
attheendoftheoffdelay.
ApplicationsUsingA Single-StageThermostat
C - HeatingSequence-- ControlThermostatSelection
DIPswitchin "Single-Stage"Position
1 - Ona callforheat,thermostat
first-stage
contactsclose
sendinga signalto theintegratedcontrol.Theintegratedcontrolrunsa self-diagnostic
programand
checkshightemperature
limitswitchesfor normally
closedcontactsandpressureswitchesfor normally
opencontacts.The
combustionair induceris energizedattheignition
speed,whichisapproximately
the
sameastheinducerspeedat70percentfiringrate.
2- Oncethe controlreceivesa signalthatthe low-fire
pressureswitchhasclosed,thecombustion
airinducer beginsa 15-second
pre-purge
attheignitionspeed.
3 - Afterthepre-purge
is complete,
a 20-second
initialignitorwarm-upperiodbegins,Thecombustion
air inducercontinues
tooperateattheignitionspeed,
4 - Afterthe20-second
warm-upperiodhasended,the
gasvalveisenergized
andignitionoccurs,whichinitiatesa 10-second
ignitionstabilization
delay.At the
sametime,thecontrolmodulesendsa signaltobegin

an indoorblower45-secondON-delay.Whenthe
delayends,theindoorblowermotoris energized
ata
speedwhichisappropriate
forthefiringrate.Afterthe
10-second
ignitionstabilization
delayexpires,theinducerspeedisadjustedto40percentspeed.The
integratedcontrolalsoinitiatesa second-stage
ondelay
(factory-set
at7 minutes;adjustable
to 12minutes).
5 - Iftheheatingdemandcontinuesbeyondthesecondstageon delay,the integrated
controlenergizesthe
combustion
airinducerat 70percentspeed.Theindoor blowermotor is adjustedto a speedwhich
matchesthetargetrate.Afixed,10-minute
third-stage
ondelayis initiated.
6 - If the heatingdemandcontrinuesbeyondthe thirdstageondelay,theintegrated
controlenergizes
theinducerat highspeed.Theindoorblowermotoris adjustedto a speedwhichis appropriate
forthe target
rate.
7 -Whenthethermostat
heatingdemandis satisfied,the
gasvalveisde-energized
andthecombustion
airinducerbeginsa 20-second
post-purge.Thefield-selectedindoorbloweroffdelaybegins.
8 - Whenthe combustion
air post-purge
periodis complete,theinduceris de-energized.
Theindoorblower
is de-energized
attheendoftheoffdelay.

Page56

Cleaning Heat Exchanger
If cleaning the heat exchanger becomes necessary, follow
the below procedures and refer to figure 1 when disassembling unit. Use papers or protective covering in front of furnace while removing heat exchanger assembly.

AWARNING

1 - Turn off electrical and gas supplies to the furnace.
2 - Remove the upper and lower furnace access panels,
3 - Disconnect the 2-pin plug from the gas valve,

At the beginning of each heating season, system should be
checked as follows by a qualified service technician:
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,

AWARNING

4 - Remove gas supply line connected to gas valve, Remove gas valve/manifold assembly,
5 - Remove sensor wire from sensor, Disconnect 2-pin
plug from the ignitor.
6 - Disconnect wires from flame roll-out switches.
7 - Remove burner box cover and remove four burner box
screws at the vestibule panel and remove burner box,
Set burner box assembly aside.
NOTE - G71MPP-135 units are secured to the vestibule panel by two additional screws. These screws
must be removed for servicing; however it is not necessary to replace the screws.
NOTE- If necessary, clean burners at this time. Follow
procedures outlined in Burner Cleaning section.
8 - Loosen three clamps and remove flexible exhaust tee.
9 - Remove 3/8 inch rubber cap from condensate drain
plug and drain. Replace cap after draining.
10 - Disconnect condensate drain line from the condensate trap, Remove condensate trap (it may be necessary to cut drain pipe), Remove screws that secure
condensate collars to either side of the furnace and remove collars. Remove drain tubes from cold end
header collector box.
11 - Disconnect condensate drain tubing from flue collar,
Remove screws that secure both flue collars into
place. Remove flue collars, It may be necessary to cut
the exiting exhaust pipe for removal of the fittings,

Filters
All G71MPP filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure proper furnace operation. Table
3 lists recommended filter sizes.
Exhaust and air intake pipes
Check the exhaust and air intake pipes 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
Winterizing

and Condensate

12 - Mark and disconnect all combustion air pressure tubing from cold end header collector box.
13 - Mark and remove wires from pressure switches. Remove pressure switches, Keep tubing attached to
pressure switches,
14 - Disconnect the 4-pin plug from the combustion air inducer, Disconnect the two wires to the backup secondary limit, if applicable. Remove four screws which secure combustion air inducer to collector box, Remove
combustion air inducer assembly, Remove ground
wire from vest panel.
15 - Remove electrical junction box from the side of the furnace.
16 - Mark and disconnect any remaining wiring to heating
compartment components. Disengage strain relief
bushing and pull wiring and bushing through the hole
in the blower deck.

Trap Care

1 - Turn off power to the unit,
2 - Have a shallow pan ready to empty condensate water.
3 - Remove the drain plug from the condensate trap and
empty water. Inspect the trap then reinstall the drain
plug and refill trap with water,
Page 57

17 - Remove the primary limit from the vestibule panel.
18 - Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger.

19- Removescrewsalongvestibulesidesand bottom
whichsecurevestibulepanelandheatexchanger
assemblyto cabinet.Removetwoscrewsfromblower
railwhichsecurebottomheatexchanger
flange,Removeheatexchanger
fromfurnacecabinet,
20- Backwashheatexchanger
withsoapywatersolution
or steam,If steamis usedit mustbe below275°F
(135°C).

22 - Reinstall heat exchanger into cabinet making sure that
the clamshells of the heat exchanger assembly are
resting on the support located at the rear of the cabinet. Remove the indoor blower to view this area
through the blower opening,
23 - Re-secure the supporting screws along the vestibule
sides and bottom to the cabinet,

25 - Reinstall the primary limit on the vestibule panel.
26 - Route heating component wiring through hole in blower deck and reinsert strain relief bushing,
27 - Reinstall electrical junction box.
28 - Reinstall the combustion air inducer. Reconnect the
4-pin plug to the wire harness. Reconnect the two
wires to the backup secondary limit, if applicable,
29 - Reinstall pressure switches and reconnect pressure
switch wiring.
30 - Carefully connect combustion air pressure switch hosing from pressure switches to proper stubs on cold end
header collector box,

32 - Reinstall condensate trap on same side as exhaust
pipe. Reconnect condensate drain line to the condensate trap.
33 - Use securing screws to reinstall flue collars to either
side of the furnace. Reconnect exhaust piping and exhaust drain tubing,
34 - Replace flexible exhaust tee on combustion air inducer and flue collars, Secure using three existing hose
clamps,
35 - Reinstall burner box assembly in vestibule area,
36 - Reconnect flame roll-out switch wires.
37 - Reconnect sensor wire and reconnect 2-pin plug from
ignitor,

44 - Follow lighting instructions to light and operate furnace for 5 minutes to ensure that heat exchanger is
clean and dry and that furnace is operating properly.
45 - Replace heating compartment access panel,
Cleaning the Burner Assembly
1 - Turn off electrical and gas power supplies to furnace,
Remove upper and lower furnace access panels,
2 - Disconnect the 2-pin plug from the gas valve,
3 - Disconnect the gas supply line from the gas valve, Remove gas valve/manifold assembly.
4 - Mark and disconnect sensor wire from the sensor. Disconnect 2-pin plug from the ignitor at the burner box.
5 - Remove burner box cover and remove four screws
which secure burner box assembly to vest panel, Remove burner box from the unit.
NOTE - G71MPP-135 units are secured to the vesti-

cabinet screws on front flange at blower

31 - Reinstall condensate collars on each side of the furnace. Reconnect drain tubing to collector box,

41 - Reconnect 2-pin plug to gas valve,
42 - Replace the blower compartment access panel.
43 - Refer to instruction on verifying gas and electrical connections when re-establishing supplies.

21 - Thoroughly rinse and drain the heat exchanger. Soap
solutions can be corrosive, Take care to rinse entire
assembly.

24-Reinstall
deck.

38 - Secure burner box assembly to vestibule panel using
four existing screws. Make sure burners line up in
center of burner ports.
39- Reinstall gas valve manifold assembly, Reconnect
gas supply line to gas valve,
40 - Reinstall burner box cover,

bule panel by two additional screws. These screws
must be removed for servicing, however it is not necessary to replace the screws.
6 - Use the soft brush attachment on a vacuum cleaner to
gently clean the face of the burners, Visually inspect
the inside of the burners and crossovers for any blockage caused by foreign matter, Remove any blockage.
7 - Reconnect the sensor wire and reconnect the 2-pin
plug to the ignitor wiring harness.
8 - Reinstall the burner box assembly using the existing
four screws. Make sure that the burners line up in the
center of the burner ports.
9 - Reinstall the gas valve manifold assembly, Reconnect
the gas supply line to the gas valve, Reinstall the burner box cover.
10 - Reconnect 2-pin plug to gas valve,
11 - Replace the blower compartment access panel.
12 - Refer to instruction on verifying gas and electrical connections when re-establishing supplies.
13- Follow lighting instructions to light and operate furnace for 5 minutes to ensure that heat exchanger is
clean and dry and that furnace is operating properly.
14 - Replace heating compartment access panel,

Page 58

Press the diagnostic push button and hold it to cycle through a menu of options. Every five seconds a new menu item will be
displayed. Release the button when the desired mode is displayed.
When the solid "E" is displayed, the control enters the Error Code Recall mode. Error Code Recall mode menu options: No change (displaying error history) remains in Error Code Recall mode; solid "-="exits Error Code Recall mode; and solid "c" clears the error history. Must
press button while flashing "c" is displayed to clear error codes.
When the solid "-" is displayed, the control enters the Field Test mode. Field Test mode menu options: Solid "C" starts pressure switch
calibration; blinking "-" exits Field Test mode.

Flash Code

Diagnostic Code / Status of Furnace

•

Idle mode (Decimal blinks at 1 Hz 1/2 sec. On and 1/2 sec. Off

CFM Display (1 sec. On 1/2 sec Off, CFM value)

Staged Cooling (1 sec. On 1/2 sec. Off or 2 Stage 1 sec. pause CFM pause, Repeat codes)

Dehumidification

Variable Capacity Heat (1 sec On 1/2 sec Off % of input rate Pause CFM Pause Repeat Codes)

Mode (1 sec. On 1 sec Off, CFM, Pause Repeat Codes)

Staged Heat (1 sec On 1/2 sec Off or2 Stage 1 sec, CFM Pause Repeat Codes)

110

Low Line Voltage

113

High Line Voltage

115

Low 24V (control will restart if the error recovers)

125

Control failed self check, internal error, failed hardware. Control will restart if error recovers

180

Outdoor Air Sensor Failure - no error if just disconnected, only show if shorted or out of range

200

Rollout circuit open or previously opened

201

Circulator / COM failure _ unable to communicate w / circulating motor (blower)

202

Circulating motor / resistor mis-match or resistor missing

204

Gas Valve Miswired _ Resume normal operation after error corrected

223
224

Low Pressure Switch Failed Open
Low Pressure Switch Failed Closed

225

High Pressure Switch Failed Open

226

High Pressure Switch Failed Closed

227

Low Pressure Switch Opened during TFI or Run mode

228
240

Unable to perform successful pressure switch calibration mode
Low Flame Mode - Run Mode

241

Flame sense out of sequence _ flame still present

250

Limit switch circuit open

270

Watchguard - Exceed maximum number of retries. No flame current sensed

271

273

Watchguard - Exceed maximum number ignition retries where the last retry was due to pressure switch
openin 9
Watchguard - Exceed maximum number of recycles where the last recycle was due to pressure switch
opening
Watchguard - Exceed maximum number of recycles where the last retry was due to flame failure

274

Watchguard - The limit remained open longer than 3 minutes

275

Watchguard - Flame sensed out of sequence; flame signal gone

290

Ignitor circuit Fault - failed ignitor or triggering circuitry

291

Restricted airflow - available CFM below min. firing rate

292

Circulator motor unable to start (seized bearings, stuck wheel, etc)

294

Inducer motor amp draw too high

310

Discharge air sensor failure - no error if just disconnected, only show if shorted or out of range

311

Restricted airflow heating mode - target input rate reduced to match available circulator CFM

312

Restricted airflow cooling or continuous fan mode - information only

272

Page 59

IGNITION AND CALL FOR LOW FIRE WITH TWO-STAGE
THERMOSTAT
_

[

Safety
Check

Is No Main Burner
Verify There
Flame

]
Indoor blower OFF
Heat OFF Delay

Inducer

After
YES

GaoVa,ve
j, {100°,orate
YES

O._100°,o_
r_:::_:_

L s_eed/

L
I
G
H
T

NO--I_-

rate speed)

Indoor

r soft Lockout:

[De-Energ,ze
Gas Valve

_o_,o_

Air Inducer
On (100%
Circuit

YES

L Error
Code
Flashes

Blower

ON (7O%)

i
YES

0
F
F

Error Code Flashes
After 5Seconds

Indoor Blower OFF After
Heat OFF Delay
I

J
Switch Opens

Error Code
Flashes

YES

Combustion Air
Inducer ON at 70%
Rate Speed

[
YES

NO_

YES
Soft Lockout:
Error Code
Flashes

No-[Pre_GtSo_,r
YES

I
__

t
-- I

Heat

i
NO

Pre-Purge
15
Seconds

,
i

-I ,onitorON
I"

L (15Interpurge
Seconds)

20 Second_

Gas Valve
Energized

L
F

I Ignition

Trial

(Ignit/r

Begin_

Indoor

ON)

Btower

Timer

Delay I

Started

1
s

, osecond

Gas Valve
NO

De-energized

YES

Post-Purge

_'1

Air Inducer
Combustion
OFF

Error Code
I_[Soft Flashes
Lockout: ]

YES

÷
A
T

Ignitor

OFF

I stW;ii',i
zF°tri°_
%tiei_Y
I

i
.....

-Z_ SOFT LOCKOUT

IS RESETAUTOMATICALLYAFTER

ACALL

FOR HEAT ACTIVE,_

Call For 2nd Stage Heat

ONE HOUR WITH

Set Target Firing Rate
Based on Thermostat
Signals Present

Call For Heat Satisfied

Page 60

CALL FOR HIGH FIRE WITH TWO-STAGE

THERMOSTAT

Thermostat
2 Stage

YES

Combustion Air Inducer ON
(100% Rate Speed)

Increase

NO---_

Combustior

Air Inducer Speed
if Not at 100%
Rate Speed

YES

Adjust Indoor
B}ower to
Appropiate speed

1
Wait for Catl for Heat Satisfied

System
,_

will always

light at 70% even if 2nd stage

call for heat is in place

If the high pressure switch does not close within 5 attempts, the system
will operate at low fire for the remainder of the call for heat at request

Page 61

CALLFOR

HEAT SATISFIED

RUN MODE (TWO-STAGE THERMOSTAT)
FIRST OR SECOND-STAGE CALL FOR HEAT
ALL INPUTS MONITORED (LIMIT, PRESSURE,
CALL FOR HEAT/COOL, FLAME LEVEL).

RUN INPUTS
MODE (SINGLE-STAGE
THERMOSTAT)
ALL
MONITORED (LIMIT,
PRESSURE,
CALL FOR HEAT/COOL, FLAME LEVEL).

2nd Stage Heat
I._NO

L. Call for Heat_

YES

I sw Combustion
Inducer
tched to 70%Airrate
speed

I_0i_s_'_0oo_'owe_
I
to appropiate

speed

---/
YES

Gas valve
De-Energized

Combustion Air Inducer OFF I
after 20-Second Post Purge

l
after OFF Delay

Wait for Call
Two-Stage
Thermostat

Wait for Call
Single-Stage
Thermostat

Page 62

IGNITION AND CALL FOR HEAT WITH SINGLE-STAGE

---

[

Safety
Check

THERMOSTAT

Is No Main Burner
Verify There
Flame

Indoor

Blower

OFF After

Heat OFF Delay
(Low Heat Speed)

De-Energize
Gas Valve

LJcombustion
Inducer

YES

Air_
ON

Indoor Blower
(100% ONSpeed)

_
NO_
J

YES

Indoor Btower
After Heat OFF

OFF
Delay

H gh HeaiSpeed

L
I
G
H
T
O
F
F

YES

v
ac I°gr
_libtiUoS_
iO_ 7A0r°/lo
nrda
t c erp e%Nd

YES

N°" I

Calibration

YES

15Sec°nds I

I 20'g°it°r
Seconds

GasVaive
Energized

(15
Interpurge
Seconds)

Begins

Indoor

Ignit/rON

Delay

]

÷
IgnitionTdal
I

YES

]
NO

Pre-Purge

--I

L
L

Soft Lockout:
Error Code
Flashes

YES

IA/nedr_
H;aE_oWF_F
OF,
F

NO
Blower

Timer

Started

I
I

D eG-aSle
rVaIgiVzee
d _Stches

_NO_

s_fu

Y E S _-[
(20
Post-Purge
Seconds)

A
T

Combustion
Inducer OFFAir]_

Soft Lockout:
Error Code
Flashes

YES

IgnitorOFF

÷
:SOFT
I Stabilization
Wait For Ignition
Delay

....

to Rate
Low Set
Firing

Move to Mid Firing
I

on DIP Switch

HC:R:

IS RESETAUTOMATICALLYAFTER

LCoYcE:
IobG IqH: ECsAErL
::

Rate

and High Firing Rate after
2nd and 3rd Stage Delays

I (based

LOCKOUT

ONE

HOUR

WITFACALL

FOR

selections)

/ qR
\_J

_,Call For Heat Satisfied

Page 63

:yHcL

i%:

:O_W:

:C:l

:HGEPcOoV_ETRRToO
L:HE CONTROL.

HEAT ACTIVE

CALLFOR

1st Stage
Request

COOLING

Cooling
Received

Energize

1st Stage

Cooling

Contactor

Compressor

& Fan

A_tned
°2°-rs
eE
_c°W_r
dO
'na
YI
Energize
Indoor Blower
Per Ramp ng Prof e

A_
z_\

_'_YES--

Energize
Cooling Contactor
2nd Stage
(Compressor
& Fan)

YES

--YES'_

I,[Energize
(High Cooling
Indoor mode)
Blower

_ES_
_%n:%_,dn;':&%er
1
NO

÷
De-Energize
2nd
Stage Cooling
Contactor
(Compressor

I
I

& Fan)l

Energ,zeand
,

MaLnt:nclonodiOlCgr
B_oOdVr
atJ
NO

l'
De-Energize

1st

Stage Cooling
Contactor
(Compressor

I
I

Fan)I

IDe-Energize'nd°°r
Bl°wer
Per Ramping

Profile

2nd stage cooling operation
requires
a 2-stage thermostat,
a 2-stage cooling system and
on-board
link W915 must be be cut. The control will not respond to a 2nd stage cooling
request unless a 1st stage cooling request is active
Indoor blower cooling mode and high cooling mode have a specific ON, OFF and speed
ramping
profiles. The specific profile is selected using the DIP switches on the control.

Page 64

CONTINUOUS
LOW

SPEED INDOOR BLOWER SEQUENCE OF OPERATION

Call for
Continuous Blower

Indoor Blower On |
(Speed Determined b_
Dip Sw tch set ings)|

YES,-I_

Blower at set speed
Maintain Indoor

_(_

Go to Call for Cooling

|"'_0

Go to Call for Heat -- Two-Stage

NO
'_"

Thermostat

for Heat

_)-YES._

Maintain indoor
|

Blower at set speed
,,,,l_l 4

)

Go to Call for Heat -- Single-Stage

Maintain Indoor
NO,,--Ip. Blower at set speed

YES

indoor Blower Per
De-Energize
Ramping
Profile

indoor blower low cooling mode and high cooling mode, have specific ON - OFF and speed
ramping profiles. The specific profile is selected using the dip switches on the control.

Page 65

Thermostat

ThefollowingrepairpartsareavailablethroughLennoxdealers.Whenorderingparts,includethecomplete
furnacemodel
numberlistedontheCSAnameplate
-- Example:G71MPP-36B-070-7,
All servicemustbe performedby a licensed
professional installer

(or equivalent), service agency, or gas supplier.

Cabinet Parts

Heating Parts

Upper access panel
Blower access panel
Top cap

Flame sensor
Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orifices
Pressure switches

Control Panel Parts
Transformer
Integrated control
Door interlock switch
Circuit breaker
Blower Parts
Blower wheel
Motor

Ignitor
Primary limit control
Secondary limit control
Flame rollout switches

Motor mounting frame
Power choke (1 hp only)
Blower housing cut-off plate

Combustion air inducer auxiliary limit
H-fitting pressure switch assembly

Job Name

Job No,

Job Location

City

State

Installer
Unit Model No.
Serial No.

City
Technician

State

Heating

Date

Section

[]

Electrical Connections Tight?
Supply Voltage
Blower Motor Amps

Blower Motor H,P.

Gas Piping Connections
Tight & Leak-Tested?

[]

Fuel Type: Natural Gas?

[]

LP/Propane Gas?

[]

Furnace Btu Input
Line Pressure
Regulator Pressure
__
w,c, - Nat,:
Flue Connections Tight?
[]
Condensate Connections Tight? []
Combustion Gas Tested?
Fan Control Setting
(45 Seconds Fixed On)
Fan Control Off Setting
Filter Clean & Secure?

[]

CO2

w,c, - LP/Propane
Proper Draft?
[]

[]

Temperature
Vent Clear?

[]

Rise
[]

Thermostat
Calibrated?

[]

Heat Anticipator Properly Set?

[]

Page 66

Level?

[]

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LENNOX Furnace/Heater, Gas Manual L0806234

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