Goodman GMH80453AN Series User manual

CUS
®
RT6621014Rev.2
June2009
Copyright ©2006 - 2009 Goodman Manufacturing Company, L.P.
This manual is to be used by qualified, professionally trained HVAC technicians only.
Goodman does not assume any responsibility for property damage or personal
injury due to improper service procedures or services performed by an unqualified
person.
•RefertoServiceManualRS6610004forinstallation,operation,andtroubleshootinginformation.
•Allsafetyinformation must be followedasprovided in the ServiceManual.
•RefertotheappropriatePartsCatalog for part number information.
•Modelnumbers listed on page 3.
GMH8 39" 80% Gas Furnace
80% AFUE, 2-Stage (Convertible),
Multi-Speed, Upflow/Horizontal
TECHNICAL MANUTECHNICAL MANU
TECHNICAL MANUTECHNICAL MANU
TECHNICAL MANUALAL
ALAL
AL

PRODUCT IDENTIFICATION
2
The model and manufacturing number are used for positive identification of component parts used in manufacturing.
Pleaseusethese numbers when requesting serviceorparts information.
Major
Furnace Type
H:Two-Stage/Multi-Speed
Product Type
G:Goodman
Supply Type
Nominal Input
AFUE
8: 80%
G M H 8 070 3 B X A A
Additional Features
N: Natural Gas
X: Low NOx
Airflow Capability
Cabinet Width
M:Upflow/Horizontal
045: 45,000Btuh
070: 70,000Btuh
090: 90,000Btuh
115: 115,000Btuh
140: 140,000Btuh
Revision
A: Initial
Release
Minor
Revision
A: Initial
Release
A: 14"
B: 171/2"
3: 1200
4: 1600
5: 2000
C: 21"
D: 24 1/2"
WARNING
WARNING HIGH VOLTAGE!
Disconnect ALL power before servicing or installing this unit. Multiple power
sources may be present. Failure to do so may cause property damage, personal
injury or death.
Installation and repair of this unit
should be performed ONLY by
individuals meeting the requirements of an "entry level
technician"asspecifiedbytheAir-Conditioning,Heating,
andRefrigerationInstitute(AHRI). Attemptingtoinstallor
repair this unit without such background may result in
product damage, personal injury or death.
Goodman will not be responsible
for any injury or property damage
arising from improper service or service procedures. If
you install or perform service on this unit, you assume
responsibility for any personal injury or property damage
which may result. Many jurisdictions require a license to
install or service heating and air conditioning equipment.
WARNING
WARNING WARNING
WARNING

PRODUCT IDENTIFICATION
3
The model and manufacturing number are used for positive identification of component parts used in manufacturing.
Pleaseusethese numbers when requesting serviceorparts information.
1GMH80453AN*
1GMH80703AN*
1GMH80704BN**
GMH80903BN**
1GMH80904BN**
1GMH80905CN**
1GMH81155CN**
1GMH81405DN**
1 Units with low NOx models available.
The United States Environmental Protection Agency (“EPA”) has issued various regulations re-
garding the introduction and disposal of refrigerants introduced into this unit. Failure to follow
these regulations may harm the environment and can lead to the imposition of substantial fines.
These regulations may vary by jurisdiction. Should questions arise, contact your local EPA office.
WARNING
WARNING
Do not connect or use any device
that is not design certified by
Goodman for use with this unit.
Serious property damage, personal injury, reduced unit
performance and/or hazardous conditions may result
from the use of such non-approved devices.
WARNING
WARNING To prevent the risk of property
damage, personal injury, or death,
do not store combustible materials or use gasoline or
other flammable liquids or vapors in the vicinity of this
appliance.
WARNING
WARNING

4
PRODUCT DESIGN
WARNING
TO PREVENT POSSIBLE PERSONAL INJURY OR DEATH DUE TO ASPHYXIATION,
THIS FURNACE MUST BE CATEGORY IVENTED. DO NOT VENT USING
CATEGORY III VENTING.
1. CategoryIVentingisventingatanon-positivepressure.
A furnace vented as Category I is considered a fan-as-
sisted appliance and the vent system does not have to
be “gas tight.” NOTE: Single stage gas furnaces with
induced draft blowers draw products of combustion
through a heat exchanger allowing, in some instances,
commonventingwithnaturaldraftappliances(i.e.water
heaters).Allinstallationsmust be vented in accordance
with National Fuel Gas Code NFPA 54/ANSI Z223.1 -
latestedition.InCanada,thefurnaces must be ventedin
accordancewiththeNational StandardofCanada,CAN/
CSAB149.1andCAN/CSAB149.2 - latest editions and
amendments.
NOTE: Theverticalheightof the Category I ventingsystem
must be at least as great as the horizontal length of the
ventingsystem.
2. Linevoltagewiringcanenterthroughthe rightorleftside
ofthefurnace.Lowvoltagewiring can enter through the
rightor left side offurnace.
3. Conversionkitsforpropanegasand highaltitudenatural
andpropanegasoperationare available. See High Alti-
tudeDerate chart for details.
4. Installer must supply the following gas line fittings, de-
pendingon which entrance isused:
Left -- Two 90° Elbows, one close nipple, straight pipe
Right --Straightpipe to reach gasvalve.
GeneralOperation
TheGMH8furnacesareequipped with anelectronicignition
deviceusedtolighttheburnersandaninduceddraftblower
to exhaust combustion products.
Aninterlockswitchprevents furnace operation if theblower
door is not in place. Keep the blower access door in place
exceptforinspection and maintenance.
This furnace is also equipped with a self-diagnosing elec-
tronic control module. In the event a furnace component is
notoperatingproperly,thecontrolmoduleLED will flash on
and off in a factory-programmed sequence, depending on
theproblemencountered. This light canbeviewed through
theobservationwindowin the blower access door.Referto
theTroubleshootingChartforfurtherexplanationoftheLED
codesandAbnormalOperation-IntegratedIgnitionControl
section in the Service Instructions for an explanation of the
possibleproblem.
Theratedheatingcapacityof the furnace should be greater
thanor equal to thetotal heat lossof the area tobe heated.
The total heat loss should be calculated by an approved
methodorinaccordance with “ASHRAE Guide” or “Manual
J-LoadCalculations”publishedbytheAir Conditioning Con-
tractors of America.
*Obtain from: American National Standards Institute 1430
BroadwayNewYork,NY10018
LocationConsiderations
• The furnace should be as centralized as is practical
with respect to the air distribution system.
• Donotinstallthefurnacedirectly on carpeting, tile, or
combustiblematerialotherthanwood flooring.
• When suspending the furnace from rafters or joists,
use 3/8" threaded rod and 2” x 2” x 3/8” angle as
shownintheInstallation andServiceInstructions.The
length of the rod will depend on the application and
clearancenecessary.
• When installed in a residential garage, the furnace
mustbepositionedsotheburnersand ignition source
are located not less than 18 inches (457 mm) above
the floor and protected from physical damage by ve-
hicles.

5
PRODUCT DESIGN
Accessibility Clearances (Minimum)
Unobstructed front clearance of 24" for servicing is rec-
ommended.
SW B
1036 11
* 24" clearance for serviceability recommended.
MINIMUM CLEARANCE TO COMBUSTIBLE MATERIALS - INCHES
** Single Wall Vent (SW) to be used only as a conncetor.
Refer to the venting tables outlined in the Installation Manual for
additional venting requirements.
Vent
Sides TopRear Front*
Note: Inallcases accessibility clearance shall takeprece-
dence over clearances from the enclosure where accessi-
bility clearances are greater. All dimensions are given in
inches.
High Altitude Derate
Whenthis furnace is installedat high altitude, theappropri-
ate High Altitude orifice kit must be installed. This is re-
quiredduetothenatural reduction in the density of boththe
gas fuel and combustion air as altitude increases. The kit
will provide the proper design certified input rate within the
specifiedaltituderange.
2000 3000 4000 4500 5000 6000 7000 8000
US BURNER
ORIFICE 44/55 44/55 45/56 45/56 46/57 47/58 47/58
CANADA BURNER
ORIFICE 44/55 47/57
HA-02 HIGH ALTITUDE CONVERSION KIT REQUIRED
Tabled data is based upon the furnace input being reduced for altitudes above sea level. U.S. 4% per 1,000 feet.
Canada 10% derate for 2,000-4,000 feet.
ELEVATION ABOVE SEA-LEVEL (FEET)
INPUT PER BURNER - 22,500 BTUH NATURAL GAS / 20,000 BTUH L.P.
High altitude kits are purchased according to the installa-
tionaltitudeandusageofeithernaturalorpropanegas.Refer
tothechartaboveforatabular listing of appropriate altitude
rangesandcorrespondingmanufacturer’shighaltitudeNatu-
ralGasandPropaneGaskits.For a tabular listing of appro-
priatealtituderangesandcorrespondingmanufacturer'sHigh
Altitude Pressure Switch kits, refer to either the Pressure
Switch Trip Points & Usage Chart in this manual or the Ac-
cessoryCharts in Service Instructions.

COMPONENT IDENTIFICATION
6
Upflow/Horizontal
1 GasValve
2 GasLineEntrance(Alternate)
3 PressureSwitch(es)
4 GasManifold
5 RolloutLimit
7 Primary Limit
8 GasLineEntrance
9 FluePipeConnection(Alternate)
10 InducedDraftBlower
11 BlowerDoorInterlockSwitch
12 IntegratedControlModule
(withfuseand diagnostic LED)
13 Transformer(40VA)
14 CirculatorBlower
15 JunctionBox
Pressure Switch
Flue Pipe Connection
Circulator
Blower
Gas Line
Entrance
Gas Line Entrance
(Alternate)
Inshot Burner
Induced Draft Blower
Gas Manifold
Rollout Limit
Primary Limit
Integrated Control Module
Junction
Box Transformer
Blower Door Interlock Switch

PRODUCT DIMENSIONS
7
GMH8
UNITS A B
GMH80453AN**
GMH80703AN** 14 12.5
GMH80704BN**
GMH80903BN**
GMH80904BN** 17.5 16
GMH80905CN**
GMH81155CN** 21 19.5
GMH81405DN** 24.5 23
All dimensions are in inches.

8
PRODUCT DESIGN
For installaions in Canada, the GMH8 furnace is certified only to 4,500 ft.
* Negative pressure readings are in inches of water column (*w.c.)
MODEL
TRIP POINT
ID BLOWER
PRESSURE
SWITCH
ID BLOWER
PRESSURE
SWITCH
PART #
MODEL
TRIP POINT
ID BLOWER
PRESSURE
SWITCH
ID BLOWER
PRESSURE
SWITCH
PART #
GMH80453AN** -0.60 B1370142 GMH80453AN** -0.60 B1370142
GMH80703AN** -0.60 B1370142 GMH80703AN** -0.60 B1370142
GMH80704BN** -0.60 B1370142 GMH80704BN** -0.47 B1370176
GMH80903BN** -0.60 B1370142 GMH80903BN** -0.75 B1370179
GMH80904BN** -0.60 B1370142 GMH80904BN** -0.75 B1370179
GMH80905CN** -0.70 B1370158 GMH80905CN** -0.60 B1370142
GMH81155CN** -0.70 B1370158 GMH81155CN** -0.70 B1370158
GMH81405DN** -0.75 013070159 GMH81405DN** -0.60 013070142
PRESSURE SWITCH TRIP POINTS
AND USAGE CHART
SQUARE NOSE ROUND NOSE
PRESSURE SWITCH TRIP POINTS
AND USAGE CHART
Part Number B1370145
Open Setting (°F) 300
GMH80453AN** 2
GMH80703AN** 2
GMH80704BN** 2
GMH80903BN** 2
GMH80904BN** 2
GMH80905CN** 2
GMH81155CN** 2
GMH81405DN** 2
ROLLOUT LIMIT SWITCHES
Part Number B1370155
Open Setting (°F) 120
GMH80453AN** 1
GMH80703AN** 1
GMH80704BN** 1
GMH80903BN** 1
GMH80904BN** 1
GMH80905CN** 1
GMH81155CN** 1
GMH81405DN** 1
AUXILIARY LIMIT SWITCHES
Part Number B1370190 B1370187 B1370188 B1370198 B1370189
Open Setting (°F) 210 160 170 150 200
GMH80453AN** 1 --- --- --- ---
GMH80703AN** --- 1 --- --- ---
GMH80704BN** --- --- 1 --- ---
GMH80903BN** --- --- --- 1 ---
GMH80904BN** --- --- 1 --- ---
GMH80905CN** --- --- --- --- 1
GMH81155CN** --- --- --- 1 ---
GMH81405DN** --- --- --- 1 ---
T.O.D. PRIMARY LIMIT

9
PRODUCT DESIGN
Coil Matches:
Alarge array of Goodman®brand coilsareavailable for use withtheGDH8 furnaces, in dedicateddownflowapplications.
These coils are available in both cased and uncased models (with the option of a field installed TXV expansion device).
These 80% furnaces match up with the existing Goodman®brand coils as shown in the chart below.
Coil Matches (Goodman®units using R22 and R-410A):
• All CAPF coils in B, C, & D widths have insulated blank off plates for use with one size smaller furnaces.
• All CAPF coils have a CAUF equivalent.
• All CHPF coils in B, C & D heights have an insulated Z bracket for use with one size smaller furnace.
• All proper coil combinations are subject to being AHRI rated with a matched outdoor unit.
C A P F 1824 A 6 A
PRODUCT
TYPE:
C: Indoor Coil
CABINET FINISH:
U:Unpainted
P: Painted
N:Unpainted Case
EXPANSION
DEVICE:
F: Flowrate
r
NOMINAL CAPACITY RANGE
@ 13 SEER
1824: 1 1/2 to 2 Tons
3030: 2 1/2 Tons
3636: 3 Tons
3642: 3 to 3 1/2 Tons
3743: 3 to 3 1/2 Tons
4860: 4 & 5 Tons
4961: 4 & 5 Tons
REVISION
A: Revision
NOMINAL WIDTH FOR GAS FURNACE
A:Fits14" Furnace Cabinet
B: Fits 17 1/2" Furnace Cabinet
C: Fits 21" Furnace Cabinet
D: Fits 24 1/2" Furnace Cabinet
N: Does Not Apply (Horizontal SlabCoils)
APPLICATION
A: Upflow/Downflow Coil
H: Horizontal A Coil
S: Horizontal Slab Coil
REFRIGERANT
CHARGE:
6: R-410A or R-22
2: R-22
4: R-410a

10
PRODUCT DESIGN
Filters:
Filters are required with this furnace and must be provided by the installer. The filters used must comply with UL900 or
CAN/ULCS111standards.Installing this furnace withoutfilterswill void the unit warranty.
This furnace has provisions for the installation of return air filters at the side and/or bottom return. The furnace will
accommodatethe following filter sizes depending on cabinet size:
RefertoMinimumFilterAreatablestodeterminefilterarearequirement.NOTE:Filterscanalsobeinstalledelsewherein
the duct system such as a central return.
Upflow Filters
FURNACE INPUT FILTER SIZE TYPE
45M 160 in2permanent
70M 241 in2permanent
90M 320 in2permanent
115M 400 in2permanent
140M 370 in2permanent
45M 320 in2disposable
70M 483 in2disposable
90M 640 in2disposable
115M 800 in2disposable
140M 738 in2disposable
PERMANENT NOMINAL 600 F.M. FACE VELOCITY
DISPOSABLE NOMINAL 300 F.M. FACE VELOCITY
MINIMUM FILTER SIZES
Cabinet
Width
(in.)
Nominal
Filter Size
(in.)
Approx.
Flow Area
(in2)
Cabinet
Width
(in.)
Nominal
Filter Size
(in.)
Approx.
Flow Area
(in2)
All 16 x 25 x 1 400 14 12 x 25 x 1 300
17-1/2 14 x 25 x 1 350
21 16 x 25 x 1 400
24-1/2 20 x 25 x 1 500
Side Return(s) Bottom Return
Thermostats:
NOTE: Complete lineup of thermostats can be found in the Thermostat Specification Sheets.

11
PRODUCT DESIGN
Dual $aver Configuration & Operation
Dual$aver
This furnace is capable of the following heating modes:
Single Stage (Factory Setting)
Modified Two-Stage
Fixed 5-Min Low Stage
Auto Time (1-12 Min) Low Stage
To change from the factory single-stage operation, adjust the
dipswitches on the ignition control as follows:
Off On
Mode
5 Min Fixed
Auto
Mode Dipswitch
2
nd
Stage Delay Dipswitch
Note: This furnace is designed to be used with a single-stage room
thermostat.
Start Start
Call for Heat Call for Heat
Safety Circuit Check Safety Circuit Check
Start Furnace
in Low Stage
Start Furnace
in Low Stage
Low-Heat Blower Low-Heat Blower
Delay Time (5 Min) Delay Time (1-12 Min)
Gas Valve Switch Gas Valve Switch
to 2nd Stage to 2nd Stage
Blower Switch to Blower Switch to
Hi Heat Operation Hi Heat Operation
T-Stat Satisfied T-Stat Satisfied
•
•
»
»

FURNACE SPECIFICATIONS
12
NOTES:
1. For elevations above 2000 feet the rating should be reduced by 4% for each 1000 feet above sea level. The furnace must not be derated,
orifice changes should only be made if necessary for altitude.
2. The total heat loss from the structure as expressed in TOTAL BTU/HR must be calculated by the manufacturers method or in accordance with
the"A.S.H.R.A.E.GUIDE"or "MANUAL J-LOAD CALCULATIONS"publishedbytheAIRCONDITIONINGCONTRACTORS OF AMERICA. Thetotal
heat loss calculated should be equal to or less than the heating capacity. Output based on D.O.E. test procedures, steady state efficiency times
output.
* Low NOx model available
1. These furnaces are manufactured for natural gas operation. Optional kits are available for conversion to propane operation.
2. Minimum Circuit Ampacity calculated as: (1.25 x Circulator Blower Amps) + I.D. Blower Amps. Wire sizes should be determined in accordance
with National Electrical Codes.Extensive wire runs will require larger wire sizes.
3 Maximum Overcurrent protections Device refers to maximumrecommended fuse or circult breaker size. May use time delay fuses or HACR-
type circuit breakers of the same sizes as noted.
MODEL
GMH80453AN* GMH80703AN*
GMH80704BN*
GMH80903BA
GMH80904BN* GMH80905CN* GMH81155CN* GMH81405DN*
Input, Natural Gas (BTUH) 45,000 70,000 70,000 90,000 90,000 90,000 115,000 140,000
Output, Natural Gas (BTUH) 136,000 56,000 56,000 72,000 72,000 72,000 92,000 112,000
Output, LP (BTUH) 32,000 48,000 48,000 64,000 64,000 64,000 80,000 96,000
A.F.U.E. 80.0% 80.0% 80.0% 80.0% 80.0% 80.0% 80.0% 80.0%
Rated External Static (" w.c.) 0.20 - 0.50 0.20 - 0.50 0.20 - 0.50 0.20 - 0.50 0.20 - 0.50 0.20 - 0.50 0.20 - 0.50 0.20 - 0.50
Temperature Rise (°F) 25 - 55 25 -55 20 - 50 30 - 60 35 - 65 35 - 65 35 - 65 40 - 70
Pressure Switch Trip Point (" w.c.) -0.60 -0.60 -0.60 -0.60 -0.60 -0.70 -0.70 -1.35
Blower Wheel (D" x W") 10x6 10x6 10x8 10x8 10x8 10x10 10x10 10x10
Blower Horsepower 1/3 1/3 1/2 1/3 1/2 1/2 1/2 3/4
Blower Speeds 4 4 4 4 4 4 4 4
Max CFM @ 0.5 E.S.P. 1344 1273 1897 1493 1895 2051 2076 2152
Power Supply (Volts/Hz/Ph) 115/60/1 115/60/1 115/60/1 115/60/1 115/60/1 115/60/1 115/60/1 115/60/1
Minimum Circuit Ampacity (MCA) 28.1 8.1 12.5 8.1 12.5 12.5 12.5 14.7
Maximum Overcurrent Device 315 15 15 15 15 15 15 15
Transformer (VA) 40 40 40 40 40 40 40 40
ID Blower Pressure Switch
Trip Point (" w.c.)
S
q
uare Nose Blowers -.60 -.60 -.60 -.60 -.60 -.70 -.70 -.75
ID Blower Pressure Switch
Trip Point (" w.c.)
Round Nose Blowers -.60 -.60 -.47 -.75 -.75 -.60 -.70 -.60
Primary Limit Setting (°F) 210 160 170 150 170 200 150 150
Auxiliary Limit Setting (°F) 120 120 120 120 120 120 120 120
Rollout Limit Setting (°F) 300 300 300 300 300 300 300 300
Fan Delay On Heating 30 30 30 30 30 30 30 30
Off Heating * 150 150 150 150 150 150 150 150
FanDelayOnCooling 55555555
Off Cooling 45 45 45 45 45 45 45 45
FanDelayOn-FanOnly 55555555
Gas Supply Pressure
(Natural/Propane) (" w.c.) 7 / 11 7 / 11 7 / 11 7 / 11 7 / 11 7 / 11 7 / 11 7 / 11
Manifold Pressure
(Natural/Propane) (" w.c.) 3.5 / 10 3.5 / 10 3.5 / 10 3.5 / 10 3.5 / 10 3.5 / 10 3.5 / 10 3.5 / 10
Orifice Size (Natural/Propane) 43 / 55 43 / 55 43 / 55 43 / 55 43 / 55 43 / 55 43 / 55 43 / 55
Number of Burners 23344456
Vent Connector Diameter (inches) 4 4 4 4 4 4 4 4
Shipping Weight (lbs.) 120 130 143 153 153 163 163 183

BLOWER PERFORMANCE SPECIFICATIONS
13
1. CFM in chart is without filters(s). Filters do not ship with this furnace, but must be provided by the installer.
2. All furnaces ship as high speed cooling. Installer must adjust blower cooling speed as needed.
3. For most jobs, about 400 CFM per ton when cooling is desirable.
4. INSTALLATION IS TO BE ADJUSTED TO OBTAIN TEMPERATURE RISE WITHIN THE RANGE SPECIFIED ON THE RATING PLATE.
5. The chart is for information only. For satisfactory operation, external static pressure must not exceed value shown on rating plate. The shaded area indicates
ranges in excess of maximum external static pressure allowed when heating. The data for 0.6" w.c. to 0.8" w.c. is shown for air conditioning purposes only.
6 The dashed (---) areas indicate a temperature rise not recommended for this model.
7. The above chart is for U.S. furnaces installed at 0-4000 feet. At higher altitudes, a properly derated unit will have approximately the same temperature rise at a
particular CFM, while the ESP at that CFM will be lower.
Tons AC
at 0.5" 0.6 0.7 0.8
ESP CFM RISE CFM RISE CFM RISE CFM RISE CFM RISE CFM CFM CFM
HIGH 3.0 1555 --- 1511 --- 1459 --- 1392 --- 1344 25 1279 1201 1120
GMH80453AN** MED 2.5 1165 28 1123 30 1100 30 1090 30 1048 32 1017 970 903
(MEDIUM) MED-LO 2.0 927 36 907 37 889 37 863 38 853 39 822 800 746
LOW 1.5 699 47 694 48 668 50 645 51 636 52 592 566 524
HIGH 3.0 1437 36 1310 39 1295 40 1310 39 1273 41 1202 1129 1039
GMH80703AN** MED 2.5 1127 46 1100 47 1095 47 1075 48 1050 49 1018 967 904
(MEDIUM) MED-LO 2.0 895 --- 917 --- 878 --- 867 --- 853 --- 830 786 743
LOW 1.5 694 --- 681 --- 663 --- 640 --- 625 --- 591 562 522
HIGH 4.0 2234 23 2151 24 2076 25 1990 26 1897 27 1803 1710 1569
GMH80704BN** MED 3.5 1676 31 1653 31 1648 31 1581 33 1555 33 1492 1414 1.35
(MEDIUM) MED-LO 3.0 1342 38 1335 39 1321 39 1313 39 1291 40 1261 1215 1149
LOW 2.5 1089 47 1085 48 1078 48 1071 48 1057 49 1040 986 932
HIGH 3.0 1593 42 1561 43 1567 42 1543 43 1493 44 1420 1343 1230
GMH80903BN** MED 2.5 118/6 56 1160 57 1160 57 1135 58 1118 59 1089 1045 983
(MEDIUM) MED-LO 2.0 957 --- 940 --- 937 --- 921 --- 895 --- 861 826 778
LOW 1.5 742 --- 710 --- 684 --- 663 --- 635 --- 611 578 476
HIGH 4.0 2182 --- 2127 31 2056 32 1974 33 1895 35 1809 1715 1588
GMH80904BN** MED 3.5 1645 40 1628 40 1615 40 1597 41 1541 43 1491 1440 1350
(MEDIUM) MED-LO 3.0 1320 49 1305 49 1310 49 1310 50 1295 51 1267 1217 1139
LOW 2.5 1063 60 1061 60 1057 61 1056 61 1039 61 1025 1005 948
HIGH 5.0 2334 --- 2334 --- 2284 --- 2135 --- 2051 35 1910 1748 1605
GMH80905CN** MED 4.0 1754 39 1735 39 1728 40 1685 40 1628 42 1551 1469 1346
(MEDIUM) MED-LO 3.5 1367 47 1380 47 1371 47 1374 48 1335 50 1293 1246 1165
LOW 3.0 1098 58 1109 59 1109 59 1088 60 1066 62 1050 998 916
HIGH 5.0 2481 --- 2395 35 2288 37 2217 38 2076 41 1999 1858 1732
GMH81155CN** MED 4.0 1738 49 1732 49 1709 50 1686 50 1639 52 1585 1492 1385
(MEDIUM) MED-LO 3.5 1364 62 1378 62 1372 62 1372 62 1350 63 1313 1261 1128
LOW 3.0 1137 --- 1142 --- 1140 --- 1114 --- 1090 --- 1056 954 860
HIGH 5.0 2554 41 2435 43 2375 44 2240 47 2152 49 2002 1883 1744
GMH81405DN** MED 4.0 1846 57 1773 59 1762 60 1712 61 1672 63 1583 1526 1442
(MEDIUM) MED-LO 3.5 1520 69 1500 70 1483 --- 1470 --- 1435 --- 1373 1308 1245
LOW 3.0 1301 --- 1274 --- 1260 --- 1231 --- 1207 --- 1177 1093 931
BLOWER PERFORMANCE
0.1 0.2 0.3 0.4 0.5
(CFM & Temperature Rise vs. External Static Pressure)
Model
Heating Speed
As Shipped
Motor
Speed
EXTERNAL STATIC PRESSURE (Inches Water Column)
()

BLOWER PERFORMANCE SPECIFICATIONS
14
30 40 50 60 70 80 90 110 120
100 130 140 150
100
90 80
70 60 50
40 30 20
10
OUTPUT BTU/HR x 1000
BTU OUTPUT vs TEMPERATURE RISE CHART
TE
M
PE
R
ATU
R
E
R
ISE
600 CFM
700
900
1000
1100
1200
1400
1600
1800
2000
2200
2400 CFM
FORMULAS
BTU OUTPUT = CFM x 1.08 x RISE
RISE = BTU OUTPUT
1.08 ÷ CFM
800

15
WIRING DIAGRAMS
Wiring is subject to change. Always refer to the wiring diagram on the unit for the most up-to-date wiring.
HIGH VOLTAGE! DISCONNECT ALL POWER BEFORE SERVICING OR INSTALLING THIS UNIT. MULTIPLE POWER SOURCES MAY BE PRESENT. FAILURE TO DO SO MAY CAUSE PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
GMH8
CAP
BK (HI)
A
UXILIARY
PROPERLY POLARIZED AND GROUNDED.
SERVICING.WIRINGTO UNIT MUST BE
WARNING:DISCONNECT POWER BEFORE
XFMR
BK
115V
24V
BR
LIMITS
WH (N)
RD (LOW)
OR(MED LOW)
BL (MED)
BLOWER
CICULATOR
24V THERMOSTAT CONNECTIONS
RO2 (11)
GND (8)
HUMIDIFIER
XFMR (6) GND
G
C
W
YTO
MICRO
R
MVL (2)
MVC (9)
PS (10)
PSO (4)
HLI (7)
HLO (1)
CONTROL MODULE
INTEGRATED
NO
SWITCH
PRESSURE
ID BLOWER
VALVE
M1
GAS
C2
C
115 VAC
FLAME SENSOR
FP
XFMR-H
XFMR (3)
RO1 (5)
24 VAC
HOT SURFACE
IGNITER
INTEGRATED CONTROL MODULE
BR
BR
IGN
IND
ID
BLWR
CIRCULATOR
BLWR
TRANSFORMER
40VA
XFMR-N
INTEGRATED CONTROL MODULE
CIR-N
5. UNIT MUST BE PERMANENTLY GROUNDED AND CONFORMTO N.E.C. AND LOCAL CODES.
ON SOME MODELS
HUMIDIFIER
24 VAC
INDUCED DRAFT
°C. USE COPPER CONDUCTORS ONLY.
BLOWER COMPARTMENT
BURNER COMPARTMENT
REPLACED, IT MUST BE REPLACED WITH WIRING MATERIAL HAVINGA TEMPERATURE
3. IF ANYOF THE ORIGINALWIRE AS SUPPLIED WITH THE FURNACE MUST BE
CORRECT COOLING CFM. (SEE SPEC SHEET FORAIR FLOW CHART)
REQUIREMENTS SO AS TO PROVIDE THE CORRECT HEATING TEMPERATURE RISE AND THE
4. BLOWER SPEEDS SHOULD BEADJUSTED BY INSTALLERTO MATCHTHE INSTALLATION
INTEGRATED CONTROL
INTERNAL TO
2. MANUFACTURER'S SPECIFIED REPLACEMENT PARTS MUST BE USED WHEN SERVICING.
1. SET HEAT ANTICIPATOR ON ROOM THERMOSTAT AT 0.7 AMPS.
BLOWER
PRIMARY LIMIT
WH
GR
BK
IGNITER
SURFACE
HOT
PU
RD
15 PIN PLUG
C
NO
SWITCH
PRESSURE
BR
SENSOR
FLAME
BK
WH
ROLLOUT LIMITS
RAPID FLASHES = REVERSED 115 VAC POLARITY/VERIFY GND
SYSTEM LOCKOUT (RETRIES/RECYCLES EXCEEDED)
7 FLASHES = LOW FLAME SIGNAL
5 FLASHES = FLAME SENSE WITHOUT GAS VALVE
4 FLASHES = OPEN HIGH LIMIT
3 FLASHES= PRESSURE SWITCH STUCK OPEN
2 FLASHES = PRESSURE SWITCH STUCK CLOSED
STEADY ON = NORMAL OPERATION
OFF = CONTROL FAILURE
5
1 FLASH =
0
1
2
3
4
PU
6 FLASHES = OPEN ROLLOUT OR OPEN FUSE
COLOR CODES:
PU PURPLE
OR ORANGE
YL YELLOW
6
7
C
BK BLACK
GR GREEN
BR BROWN
PK PINK
RD RED
GY GRAY
BLBLUE
WH WHITE
PU
RATING OF AT LEAST 105
NOTES:
TO 115VAC/ 1Ø/60HZPOWERSUPPLYWITH
OVERCURRENT
PROTECTIONDEVICE
JUNCTION BOX
SWITCH
LINE-H
DOOR
LGND
LINE-N
DISCONNECT
N
SWITCH(TEMP.)
FIELDSPLICE
SWITCH(PRESS.)
PROT.DEVICE
OVERCURRENT
EQUIPMENTGND
TERMINAL
JUNCTION
HI
VOLTAGE FIELD
HI
VOLTAGE (115V)
LOW
VOLTAGE FIELD
LOW
VOLTAGE (24V)
PLUGCONNECTION
IGNITER
FIELDGND
IND-N
IGN-N
JUNCTION
BOX
OVERCURRENT PROTECTION
POWER SUPPLY WITH
TO 115 VAC/ 1/60HZ
GND
LINE-N
LINE H
DEVICE
DOOR SWITCH
WH
BK
SWITCH LOCATED IN BLOWER
COMPARTMENT ON SOME MODELS
RD
RD
BL
PU
YL
OR
BR
(SINGLECONTROLON SOME MODELS)
PARK
78
654
CGRWY
5 MIN
2 STG MODE
2
1
321
CONTROL MODULE
INTEGRATED
PM
1HIC32
2 STAGE
GAS VALVE
WH
24 VAC
HUMIDIFIER
RD
HI
MVH (12)
A
IR CLEANER
ELECTRONIC EAC-N
EAC-H
6.TORECALLTHELAST5FAULTS,MOSTRECENTTOLEASTRECENT,DEPRESSSWITCH
FORMORETHAN2SECONDSWHILEINSTANDBY(NOTHERMOSTATINPUTS).
BR BL
BR
BR
BL
BK
BK
YL
YL
RD
YL YL
PU
OR
BR
WH
WH
WH
YL
BL
RD
8
8 FLASHES = CHECK IGNITER OR IMPROPER GROUND

16
SCHEMATICS
HIGH VOLTAGE!
DISCONNECT ALL POWER BEFORE SERVICING OR INSTALLING THIS
UNIT. MULTIPLE POWER SOURCES MAY BE PRESENT. FAILURE TO
DO SO MAY CAUSE PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
TYPICALSCHEMATIC
GMH8____**MODEL FURNACES
WR50M56-289INTEGRATEDIGNITION CONTROL
.0005
3M K4
K2
HI
HEAT
COOL PARK CIR
NEU
K5
GAS VALVE
HIGH
LIMIT AUX
LIMIT
PRESSURE
SWITCH
FLAME
SENSOR
PROBE
IGNITOR
FP IGN GND MV MLV PS HLO HLI
CIRCULATOR
BLOWER
XFMR
HOT
XFMR
NEU
24 VAC
TH
RO1
RO2
R
TR
C
Y
G
W
COMPRESSOR
CONTACTOR
COIL
THERMOSTAT
R
Y
G
W
INDUCER
IND
ELECTRONIC
AIR CLEANER
EAC EAC
NEU
K6 ROLLOUT
SWITCH
K1
FACTORY
JUMPER
FACTORY
JUMPER
PSO
K2
K3
K3
LO
HEAT
COM
PM
HI
2-STAGE
K7
This schematic is for reference only. Not all wiring is as shown above. Always refer to the appropriate wiring diagram for the unit being serviced.