Nordyne G6 Series User manual

G6 Series
80+ Mid Efficiency
Upflow Horizontal/
Downflow Models
Service Manual

G6RA, G6RK Service Manual 1
1. Introduction .............................................................. 2
ModelIdentificationCode ......................................... 5
SerialNumberIdentificationCode............................. 5
FurnaceSpecifications ......................................... 5, 6
ClearancestoCombustibles..................................... 6
2. CirculatingAir Supply ............................................... 7
ReturnAir ................................................................. 7
AirflowData.............................................................. 8
3. VentingandCombustionAirRequirements............... 9
Installation In An Unconfined Space......................... 9
Installation in a Confined Space ............................... 9
Air From Inside....................................................... 10
Outdoor Air Using Vertical Ducts ............................ 10
Air Directly Through An Exterior Wall ..................... 11
OutdoorAirUsing HorizontalDucts ........................ 11
4. Category I Common Venting ................................ 12
Category III Horizontal Venting............................. 13
For G6RA.......................................................... 13
For G6RK.......................................................... 14
Vent Kit Bleed Tube Chart...................................... 40
Through-The-WallPowerVenting............................ 15
LocationofOutdoorTermination............................. 16
Horizontal Installation........................................ 16
Flexible Vent Systems ........................................... 17
LeakCheck ............................................................ 17
5. ElectricalWiring ..................................................... 17
6. SystemOperationInformation ................................ 17
SequenceofOperation ........................................... 17
HeatingMode ......................................................... 17
CoolingMode ......................................................... 18
FanMode ............................................................... 18
FurnaceFailsToOperate ....................................... 18
Twinning ................................................................. 18
TABLE OF CONTENTS
7. ComponentParts ................................................... 19
LineVoltage ........................................................... 19
SupplyVoltage ....................................................... 20
TroubleShootingSequence.................................... 21
UTECControlBoardSequence .............................. 22
WiringDiagram-G6RAUpflow............................... 23
WiringDiagram-G6RKDownflow........................... 24
PolarityandGround................................................ 25
BlowerDoorSwitch ................................................ 25
Transformer............................................................ 25
LowVoltageWiring................................................. 26
ControlBoard ....................................................26,27
HighLimitControls ................................................. 28
Main Air Limit Control ............................................. 29
VentLimit Control................................................... 29
RollOutLimitControl ............................................. 30
DraftInducerMotor................................................. 30
PressureSwitch ..................................................... 30
HotSurfaceIgnitor ................................................. 33
Gas Valve .............................................................. 34
FlameSensor......................................................... 35
HeatExchangerandIts Components ..................... 35
8. BlowerPerformance ............................................... 36
9. FlueGasTemperature............................................ 36
10. Gas ConversionandHighAltitude .......................... 37
HighAltitudeDerate ............................................... 37
Conversion ............................................................. 37
Verifyingand AdjustingFiring Rate......................... 37
11. Accessories ........................................................... 39
Dual Fuel Kit .......................................................... 39
NaturalGas toPropaneConversion Kits ................ 39
ElectronicAirCleaner............................................. 39

2 G6RA, G6RK Service Manual
INTRODUCTION
This service manual is designed to be used in conjunction with the installation manual provided with
each furnace.
Thisfurnacerepresentstheverylatestinmidefficiencygasfurnacetechnology.Consequently,certain
controls within the furnace consist of highly sophisticated electronic components which are not user
serviceable. Therefore, it is essential that only competent, qualified service personnel attempt to
install, service, or maintain this product.
This service manual was written to assist the professional HVAC service technician to quickly and
accurately diagnose and repair any malfunctions of this product.
This service manual covers both upflow/horizontal models and downflow models installed as
CategoryIandCategoryIIIapplications.Theoveralloperationofallthesemodelsisbasicallythesame
with the exception of certain controls that are unique to a particular model.
This manual, therefore, will deal with all subjects in a general nature (I.E. all text will pertain to all
models) unless that subject is unique to a particular model or family, in which case it will be so
indicated.
Itwillbenecessarythenfor youto accuratelyidentifytheunityouareservicing,soyoumaybecertain
of the approved diagnosis and repair. (See Unit Identification on Page 4. )
This manual was prepared by the senior Technical Service and Communication Departments.
The information contained in this manual is intended for use by a qualified service technician who is
familiar with the safety procedures required in installation and repair and who is equipped with the
proper tools and testing instruments.
Installationsandrepairsmadebyunqualifiedpersonscanresultinhazardssubjectingtheunqualified
person making such repairs to the risk of injury or electrical shock which can be serious or even fatal
not only to them, but also to persons being served by the equipment.
If you install or perform service on equipment, you must assume responsibility for any bodily injury or
propertydamagewhichmayresulttoyouorothers.Wewillnotberesponsibleforanyinjuryorproperty
damage arising from improper installation, service, and/or service procedures.
WARNING
!

G6RA, G6RK Service Manual 3
Furnace Dimensions Shipping
Input A B C Flue Outlet Weight D
Model (Btuh) (in.) (in.) (in.) (in.) (lbs) (IN.)
G6RA045(*)-08 45,000 14 1/4 12 3/4 3 1/4 3 108 11 3/4
G6RA060(*)-12 60,000 14 1/4 12 3/4 3 3/4 4 120 11 3/4
G6RA072(*)-12 72,000 14 1/4 12 3/4 3 3/4 4 120 11 3/4
G6RA072(*)-16 72,000 19 3/4 18 1/4 3 3/4 4 125 17 1/4
G6RA096(*)-12 96,000 19 3/4 18 1/4 3 3/4 4 157 17 1/4
G6RA096(*)-16 96,000 19 3/4 18 1/4 3 3/4 4 158 17 1/4
G6RA096(*)-20 96,000 22 1/2 21 3 3/4 4 165 20
G6RA120(*)-16 120,000 19 3/4 18 1/4 3 3/4 4 172 17 1/4
G6RA120(*)-20 120,000 22 1/2 21 3 3/4 4 174 20
G6RA144(*)-20 144,000 22 1/2 21 4 1/4 5 183 20
FURNACE DIMENSIONS AND
SHIPPING WEIGHTS
Unit Shown in Upflow Position
Rotate 90 Clockwise or Counter Clockwise
for Horizontal Application
23
3/4
19
3/4
3/4
43
25
1/8
25
1
/ 4 25
5/8
23
27
5
/ 8
15 20
1/2
25
1/4
33 30
1/4
A
B
C
FLUE
OUTLET
1
1/2
X 3
1/2
Cut-out for
Gas Connection
3/4 3/4
1
1/4
3/4
7/8
Cut-out for Electric
Connection
1
1/2
X 3
1/2
Cut-out for
Gas Connection
7/8
Cut-out for
Electric Connection
Return
Air Opening
(Side)
1 1/4 1 1/4D 23
Return Air Opening
(Bottom)
7/8
FURNACE SPECIFICATIONS - Upflow G6RA Models
Figure 1. G6RA Unit Dimensions
Table 1A. G6RA Furnace Dimensions and Shipping Weights

4 G6RA, G6RK Service Manual
FURNACE SPECIFICATIONS - Downflow G6RK Models
Figure 1A. G6RK Unit Dimensions
Cut-out for Electric
Connection
Both sides
Cut-out for Gas Connection
1-1/2 x 3-1/2 (both sides)
27 7/8"
3/4" 19 3/4"
23 5/8"
19 3/4" 3/4"
C
C
L
3/4"
3/4"
43"
4" Dia. Vent
Cut - out for
Gas Connection
A
B
B
24 1/2"
25"
15 1/2"
27 1/8"
25"
3/4"
C
L
(Bottom Opening)
(Bottom Opening)
10 1/4"
Table 1B. G6RK Furnace Dimensions and Shipping Weights
Furnace Shipping
Model Input A B C Weights
Number (Btuh) inches inches inches (lbs)
G6RK060C-12 60,000 14 1/4 12 3/4 5 1/2 105
G6RK072C-12 72,000 14 1/4 12 3/4 5 1/2 115
G6RK072C-16 72,000 19 3/4 18 1/4 11 130
G6RK096C-12 96,000 19 3/4 18 1/4 11 150
G6RK096C-16 96,000 19 3/4 18 1/4 11 158
G6RK120C-20 120,000 19 3/4 18 1/4 11 170
FURNACE DIMENSIONS AND
SHIPPING WEIGHTS
Dimensions

G6RA, G6RK Service Manual 5
MODEL IDENTIFICATION CODE
SERIAL NUMBER IDENTIFICATION CODE
NominalCFMAirflow
@ 0.5" WC
08 = 800 16 = 1600
12 = 1200 20 = 2000
G6 R 040 C16A
C = U.S. / Canada
N = NOx U.S.
DesignSeries
A=80+AFUEUpflow/
Horizontal
K=80+AFUEDownflow
Residential
Gas
HeatingInput-Btuh
040 = 40,000 080 = 80,000 120 = 120,000*
060 = 60,000 100 = 100,000 (*Available in upflow only)
ProductionCode
G6 R 97 10 01234
Month
DesignSeries
Residential
Gas
Year
FURNACE SPECIFICATIONS
G6RA MODEL NUMBERS: -045( )08 -060( )12 -072( )12 -072( )16 -096( )12 -096( )16 -096( )20 -120( )16 -120( )20 -144( )20
Input-Btuh (a) 45,000 60,000 72,000 72,000 96,000 96,000 96,000 120,000 120,000 144,000
Heating Capacity - Btuh 36,000 48,000 58,000 58,000 77,000 77,000 77,000 96,000 96,000 115,000
AFUE 80+ 80+ 80+ 80+ 80+ 80+ 80+ 80+ 80+ 80+
Max. Htg. Ext. St. Press. In W.C. .5 .5 .5 .5 .5 .5 .5 .5 .5 .5
Blower D x W 10 x 6 10 x 6 10 x 6 10 x 10 10 x 10 10 x 10 11 x 10 10 x 10 11 x 10 11 x 10
Motor H.P. -Speed -Type 1/5 - 3 - PSC 1/3 - 3 - PSC 1/3 - 3 -PSC 1/2 - 4 -PSC 1/3 - 3 - PSC 1/2 - 4 -PSC 3/4 - 4 -PSC 1/2 - 4 -PSC 3/4 - 4 -PSC 3/4 - 4 -PSC
Motor FLA 2.8 6.0 6.0 7.9 6.0 7.9 11.1 7.9 11.1 11.1
Temperature Rise Range - °F 45 - 75 45 - 75 45 - 75 40 - 70 50 - 80 50 - 80 40 - 70 50 - 80 45 - 75 45 - 75
Approximate Shipping Wt. - lbs. 108 120 120 125 157 158 165 172 174 183
All models are 115 V, 60 HZ. Gas connections are 1/2" N.P.T
AFUE= Annual Fuel Utilization Efficiency
Input-Btuh (a) 60,000 72,000 72,000 96,000 96000 120,000
Heating Capacity - Btuh 48,000 58,000 58,000 77,000 77,000 96,000
AFUE 80+ 80+ 80+ 80+ 80+ 80+
Blower D x W 10 x 6 10 x 6 10 x 10 10 x 8 10 x 10 11 x 10
Motor H.P. -Speed -Type 1/3 - 3 - PSC 1/3 - 3 - PSC 1/2 - 4 -PSC 1/3 - 3 -PSC 1/2 - 4 -PSC 3/4 - 4 -PSC
Motor FLA 6.0 6.0 7.9 6.0 7.9 11.1
Maximum Ext. SP - In. W.C. 0.5 0.5 0.5 0.5 0.5 0.5
Temperature Rise Range - °F 35 - 65 45 - 75 35 - 65 45 - 75 40 - 70 40 - 70
Approx. Shipping Wt. lbs. 105 115 130 150 158 170
G6RK MODEL NUMBERS
-060C-12 -072C-12 -072C-16 -096C-12 -096C-16 -120C-20

6 G6RA, G6RK Service Manual
DownflowWarning(G6RKModels):
Thedesignofthedownflowfurnaceiscertifiedfornaturalor
propanegasandforinstallationonnon-combustibleflooring.
A special combustible floor sub-base is required when
installing on a combustible floor. Failure to install the sub-
basemayresultinfire,propertydamageandpersonalinjury.
The special downflow sub-bases are factory supplied
accessories, part numbers 902677 and 902974. When the
furnace is installed on a factory or site-built cased air
conditioning coil, the sub-base is not necessary. However,
theplenumattachedtothecoilcasingmustbeinstalledsuch
thatitssurfacesareatleast1"fromcombustibleconstruction.
Agas-firedfurnaceinstalledinaresidentialgaragemustbe
installed so the burners and the ignitor are located not less
than 18 inches (457 mm) above the floor, and the furnace
must be located or protected to avoid physical damage by
vehicles.
Clearances to Combustibles
ThisfurnaceisDesignCertifiedbyA.G.A.Laboratories,and
approvedbyCanadianGasAssociation(CGA)fortheminimum
clearancestocombustiblemateriallistedinTable2.Seethe
furnace name plate, located inside the furnace cabinet, for
specificmodelnumberandclearanceinformation.
TheG6RAfurnaceiscertifiedforuseonwoodflooring.This
furnacemustnotbeinstalleddirectlyoncarpeting,tile,orany
combustiblematerialotherthanwoodflooring.
CAUTION:
!
The Downflow Sub-base must not be installed
directly on carpeting, tile, or any combustible
material other than wood flooring.
RIGHT
SIDE
DOWNFLOW APPLICATION
Do not place combustible material on or
againstthe furnacecabinet orwithin6 inches
of the vent pipe. Do not place combustible
materials, including gasoline and any other
flammable vapors and liquids, in the vicinity
of the furnace.
WARNING:
!
Table 2. Minimum Clearances to Combustible Material
LEFT
SIDE RIGHT
SIDE
G6RA Furnaces
BOTTOM
TOP
LEFT
SIDE
HORIZONTAL APPLICATION
UPFLOW APPLICATION
TOP
LEFT
SIDE
BOTTOM
TOP
RIGHT
SIDE
G6RK Furnace
BOTTOM
Vent
Connector
T
y
pe Standard Single Wall Metal Vent Type B Double Wall Metal Vent
LEFT SIDE 1" 1"
RIGHT SIDE 0" 0"
VENT 6" 1"
BACK 0" 0"
BOTTOM 0" 0"
TOP 5" 0"
* FRONT 4" 4"
* Allow 36" minimum clearance for service.
HORIZONTAL INSTALLATION CLEARANCES
Vent
Connector
Type Standard Single Wall Metal Vent Type B-1 Double Wall Metal Vent
LEFT SIDE 0" 0"
RIGHTSIDE 5" 0"
VENT
6" 1"
BACK
0" 0"
BOTTOM 0" 0"
TOP 1" 1"
* FRONT 4" 4"
* Allow 36" minimum clearance for service.
UPFLOW/DOWNFLOW INSTALLATION CLEARANCES

G6RA, G6RK Service Manual 7
Ifacoolingsystem is installed in parallel with the furnace, a
dampermustbeinstalledtopreventchilledairfromentering
the furnace and condensing on the heat exchanger. If a
manuallyoperated damper is installed, itmust be designed
sothatoperationofthefurnaceispreventedwhenthedamper
isinthecoolingpositionandoperationofthecoolingsystem
is prevented when the damper is in the heating position.
Return Air
In applications where the supply ducts carry heated air to
areasoutsidethespaceinwhichthefurnaceisinstalled,the
returnairmustbedeliveredtothefurnacebyduct(s)sealed
tothefurnacecasing,runningfullsizeandwithoutinterruption
betweentheoutsidespaceandtheoneinwhichthefurnace
is installed.
WARNING
!
The solid base of the furnace must be in place
when the furnace is installed with side return air
ducts. Removal of all or part of the base could
cause products of combustion to be circulated
into the living space and create potentially
hazardous conditions, including carbon
monoxidepoisoningthatcouldresultinpersonal
injury or death.
Products of combustion must not be allowed to
enter the return air ductwork or the circulating
air supply. Failure to prevent products of
combustionfrombeing circulated into the living
space can result in personal injury or death.
All return ductwork must be adequately sealed,
all joints must be taped, and the ductwork must
be secured to the furnace with sheet metal
screws. When return air is provided through the
bottom of the furnace, the joint between the
furnaceandthereturnairplenummustbesealed.
The floor or platform on which the furnace is
mounted must provide sound physical support
of the furnace with no gaps, cracks, or sagging
between the furnace and the floor or platform.
Return air and circulating air ductwork must not
beconnectedtoanyotherheatproducingdevice
such as fireplace insert, stove, etc.
WARNING
!
Aclearanceofatleast36inchesfromthefrontofthefurnace
is recommended to allow for servicing and maintenance.
Where accessibility clearances are greater than the
minimumclearances,accessibilityclearancesmusttake
precedence.
CIRCULATING AIR SUPPLY
General
Plenumsandairductsmustbeinstalled inaccordance with
the Standard for the Installation of Air Conditioning and
VentilatingSystems(NFPANo.90A)ortheStandardforthe
InstallationofWarmAirHeatingandAirConditioningSystems
(NFPANo. 90B).
If outside air is utilized as return air to the furnace for
ventilation or to improve indoor air quality, the system must
be designed so that the return air to the furnace is not less
than50°F(10°C)duringheatingoperation.Ifacombinationof
indoorandoutdoorairisused,theductsanddampersystem
mustbedesignedsothatthereturnairsupplytothefurnace
isequaltothereturnairsupplyundernormal,indoorreturnair
applications.
When a cooling system is installed which uses the furnace
blowertoprovideairflowovertheindoorcoil,thecoilmustbe
installeddownstream(ontheoutletside)orinparallelwiththe
furnace. Thereturnairductworkmaybeconnectedtoanyorallofthe
following:leftside return,rightside return,orbottomreturn.
Table 3 shows the airflow data for each furnace model.
Where maximum airflow is 1800 CFM or more, two
openings must be used.

8 G6RA, G6RK Service Manual
Table 4. Furnace Airflow Data
CAPACITIES—FurnaceAirflowData
** Factory wired cooling speed tap
** Factory wired heating speed tap
- Not Recommended
NOTE: Airflow rates of 1800 CFM or more require two
return air connections. Data is for operation with filter(s).
Downflow Furnace Airflow Data
G6RK
Furnace Motor Motor
Model No. Speed HP CFM Rise CFM Rise CFM Rise CFM Rise CFM Rise
High * 1380 - 1345 - 1330 - 1260 - 1230 -
060C-12 Medium 1/3 1180 39 1145 40 1130 41 1110 42 1080 43
Low ** 830 56 810 57 805 58 795 58 780 59
High * 1380 - 1345 - 1330 - 1260 - 1230 -
072C-12 Medium 1/3 1180 47 1145 49 1130 49 1110 50 1080 52
Low ** 830 67 810 69 805 69 795 70 780 71
High * 1850 - 1790 - 1775 - 1755 - 1735 -
072C-16 Med-High 1/2 1460 - 1435 - 1420 - 1400 - 1380 -
Med-Low 1210 46 1195 47 1180 47 1160 48 1140 49
Low ** 1020 55 1010 55 995 56 975 57 955 58
High * 1475 50 1460 51 1445 51 1430 52 1410 53
096C-12 Medium ** 1/3 1200 62 1195 62 1180 63 1165 64 1145 65
Low 795 - 785 - 770 - 755 - 735 -
High * 1950 - 1890 - 1865 - 1835 - 1805 -
096C-16 Med-High 1/2 1600 46 1580 47 1555 48 1525 49 1495 50
Med-Low ** 1375 54 1360 55 1335 56 1305 57 1275 58
Low 1180 63 1165 64 1440 65 1110 67 1080 69
High * 2440 - 2395 - 2385 - 2375 - 2360 -
120C-20 Med-High 3/4 1920 48 1910 48 1900 49 1890 49 1875 49
Med-Low** 1630 57 1620 57 1610 58 1600 58 1585 59
Low 1430 65 1425 65 1415 66 1405 66 1390 67
External Static Pressure (inches Water Column)
0.1 0.2 0.3 0.4 0.5
Upflow Furnace Airflow Data
G6RA External Static Pressure (Inches Water Column)
Furnace Motor Motor 0.1 0.2 0.3 0.4 0.5
Model No. HP Speed CFM Rise CFM Rise CFM Rise CFM Rise CFM Rise
High * 1000 - 970 - 950 - 920 - 870 -
045C-08 1/5 Medium 760 46 740 47 730 47 720 48 690 50
Low ** 630 55 620 56 610 57 600 58 570 61
High * 1380 - 1350 - 1310 - 1260 - 1210 -
060C-12 1/3 Medium 1220 - 1190 - 1160 - 1120 - 1070 -
Low ** 820 57 800 58 780 59 760 61 730 63
High * 1380 - 1350 - 1310 - 1260 - 1210 -
072C-12 1/3 Medium 1220 46 1190 47 1160 48 1120 49 1070 52
Low ** 820 68 800 69 780 71 760 73 730 76
High * 1980 - 1910 - 1830 - 1760 - 1660 -
072C-16 1/2 Med-High 1710 - 1660 - 1610 - 1540 - 1470 -
Med-Low 1490 - 1470 - 1420 - 1380 - 1320 -
Low ** 1270 44 1250 45 1230 45 1190 47 1140 49
High * 1530 - 1450 - 1390 - 1300 - 1220 -
096C-12 1/3 Medium** 1380 64 1320 67 1250 71 1190 75 1100 81
Low 930 - 900 - 870 - 820 - 750 -
High * 1980 - 1910 - 1840 - 1760 - 1680 -
096C-16 1/2 Med-High 1720 - 1670 - 1610 - 1560 - 1480 -
Med-Low ** 1470 50 1440 52 1410 53 1370 54 1320 56
Low 1270 58 1240 60 1220 61 1190 62 1140 65
High * 2340 - 2290 - 2280 - 2180 - 2150 -
096C-20 3/4 Med-High 1910 - 1880 - 1860 - 1830 - 1810 -
Med-Low 1520 49 1510 49 1490 50 1480 50 1460 51
Low ** 1370 54 1350 55 1340 55 1320 56 1300 57
High * 1900 - 1830 - 1750 - 1630 - 1580 -
120C-16 1/2 Med-High ** 1720 54 1670 56 1610 58 1560 59 1480 63
Med-Low 1450 64 1420 65 1380 67 1340 69 1280 72
Low 1260 - 1230 - 1200 - 1170 - 1120 -
High * 2300 - 2250 - 2190 - 2130 - 2090 -
120C-20 3/4 Med-High 1910 49 1880 49 1860 50 1830 51 1800 52
Med-Low** 1540 60 1530 61 1520 61 1500 62 1480 63
Low 1320 - 1310 - 1300 - 1280 - 1260 -
High * 2240 - 2190 - 2130 - 1070 - 2020 -
144C-20 3/4 Med-High** 1900 49 1860 50 1820 51 1780 52 1740 53
Med-Low 1520 61 1510 61 1490 62 1480 63 1450 64
Low 1330 - 1310 - 1290 - 1280 - 1250 -

G6RA, G6RK Service Manual 9
Figure 1. G6RA Horizontal Installation
Suspended in Attic or Crawl Space
Combustion air must not be drawn from a
corrosive atmosphere.
CAUTION:
!
WARNING:
Furnace installation using methods other
than those described in the following
sectionsmustcomplywiththeNationalFuel
Gas Code and all applicable local codes to
provide sufficient combustion air for the
furnace.
!
VENTING AND COMBUSTION
AIR REQUIREMENTS
General
Provisionsmustbemadeintheinstallationofthisfurnaceto
provideanadequate supply of air for combustion. Detailed
instructions for determining the adequacy of an installation
canbefoundinthecurrentrevisionoftheNationalFuelGas
Code(ANSIZ223.1/NFPA54)orinapplicablelocalbuilding
codes. Consultlocalcodesforspecialrequirements.For
CanadianinstallationsconsultCanadianInstallationsCodes
and(CAN/CGAB149.1or .2).
Ifthefurnaceisoperatedwithinadequateairforcombustion
one of the flame roll-out switches located in the burner
compartmentortheventswitchwillopen,turningoffthegas
supply to the burners. These safety devices are manually
reset switches. DO NOT install jumper wires across these
switches to defeat their function. DO NOT reset a switch
without identifying and correcting the fault condition. If a
switchmustbe replaced,use onlythecorrect partspecified
in the Replacement Parts List.
Air openings in the furnace door, warm air registers, and
return air grilles must not be restricted.
Tomaximizeheatexchangerlife,thecombustionairmustbe
freeofchemicalswhichformcorrosiveacidiccompoundsin
thecombustiongases. Someexamplesofthesechemicals
arechlorine,fluorine, andsulphur. Somecommon sources
ofthesechemicalsaredetergents,bleaches,aerosolsprays,
cleaning solvents, and a wide variety of commercial and
householdproducts.
When installing a furnace in a commercial building or in a
laundryroomorworkshopofaresidence,itmaybenecessary
to provide outside air to the furnace for combustion.
InstallationIn An UnconfinedSpace
An unconfined space is an area including all rooms not
separatedbydoorswithavolumegreaterthan50cubicfeet
per1,000Btuh ofthecombined inputratesof allappliances
which draw combustion air from that space.
Forexample,aspaceincludingawaterheaterratedat45,000
Btuh input and a furnace rated at 75,000 Btuh requires a
volume of 6,000 cubic feet [50 x (45 + 75) = 6,000] to be
consideredunconfined. Ifthespacehasan8footceiling,the
floorareaof the space must be 750squarefeet (6,000 / 8 =
750). Ingeneral,afurnaceinstalledinanunconfinedspace
willnotrequireoutsideairforcombustion. However,in“tight”
buildings(withweatherstrippingandcaulktoreduceinfiltration),
itmaybenecessarytoprovideoutsideairtoensureadequate
combustionandventing,eventhoughthefurnaceislocated
inanunconfined space.
Installation In A Confined Space
A confined space is an area with volume less than 50 cubic
feet per 1,000 Btuh of the combined input rates of all
appliancesdrawingcombustionairfromthatspace. Furnace
closets, small equipment rooms and garages are confined
spaces. Furnacesinstalledinaconfinedspacewhichsupply
heated air to areas outside the space must draw return air
from outside the space and must have the return air ducts
tightlysealedtothefurnace. Aconfinedspacemusthave
two openings into the space for combustion air. One
openingmustbewithin12inchesoftheceiling,andthe
othermust be within12inches of thefloor.Therequired
sizingoftheseopeningsisdeterminedby whetherinside or
outside air is used to support combustion, the method by
which the air is brought to the space, and by the total input
rate of all appliances in the space.
HorizontalFurnaceInstallation
TheG6RAcanbeinstalledhorizontallyinanattic,basement,
crawlspaceoralcove.Itcanbe suspendedfromaceilingin
abasementorutilityroomineitherarighttoleftairfloworleft
to right airflow. (See Figures 1 and 2.)

10 G6RA, G6RK Service Manual
Figure 2. G6RA Horizontal installation on a Platform
Figure 3. Equipment in a Confined Space with all
Combustion Air Drawn from the Inside
Figure 4. Equipment in a Confined Space with all
Combustion Air Drawn from the Outside
through Vertical Ducts
If the furnace is to be suspended from the ceiling, it will be
necessary to use steel straps around each end of the
furnace.Thesestrapsshouldbeattachedtothefurnacewith
sheetmetalscrewsandtotherafterswithbolts.Thefurnace
couldalsobesuspendedbyanangleironframeboltedtothe
rafters.(SeeFigure1.)
Thirty six (36) inches between the front of the furnace and
adjacentconstructionorotherappliancesshouldbemaintained
for service clearance.
Keep all insulating materials away from the louvered door.
Insulating materials may be combustible.
The G6RA may be installed directly on combustible wood
flooring or supports, if type "B-1" vent pipe is used (See
Figure 2). It is recommended for further reduction of fire
hazardthatcementboardorsheetmetalbeplacedbetween
the G6RA and the combustible floor and extend 12 inches
beyondthefront of the louvered door.
AirFrom Inside(SeeFigure 3)
If combustion air is taken from the heated space, the two
openingsmust each havea freearea ofatleast onesquare
inch per 1,000 Btuh of total input of all appliances in the
confinedspace,butnotlessthan100squareinchesoffree
area.Forexample,ifthecombinedinputrateofallappliances
is less than or equal to 100,000 Btuh, each opening must
have a free area of at least 100 square inches. If the
combinedinput rate ofall appliances is120,000 Btuh, each
openingmusthaveafreeareaofatleast120squareinches.
Total Input
Rating (Btu/hr)
40,000
60,000
80,000
100,000
120,000
140,000
160,000
Round Duct
Diameter
12"
12"
12"
12"
13"
14"
15"
Minimum
Free Area
(Each Opening)
100 sq. in.
100 sq. in.
100 sq. in.
100 sq. in.
120 sq. in.
140 sq. in.
160 sq. in.
Furnace
Openings to
adjacent space.
Each opening must
be at least 100 sq. in.
or 1 sq. in. per 1000
Btuh of total input
rating, whichever is
greater. See minimum
area per table.
12" Max.
12" Max.
Water Heater
Vent or
Chimney
Total Input
Rating (Btu/hr)
40,000
60,000
80,000
100,000
120,000
140,000
160,000
Minimum
Free Area
(Each Opening)
10 sq. in.
15 sq. in.
20 sq. in.
25 sq. in.
30 sq. in.
35 sq. in.
40 sq. in.
Round Duct
Diameter
4"
5"
5"
6"
6"
7"
8"
Inlet Air Duct must
be at least 1 sq. in.
per 4,000 Btuh of
total input rating.
Inlet and Outlet Ducts
must extend above
attic insulation.
Outlet Air Duct must
be at least 1 sq. in.
per 4,000 Btuh of
total input rating.
Ventilation Louvers at
each end of attic
Attic
Insulation
12" Max
a. All Combustion Air from Ventilated Attic.
Furnace
Water Heater
Vent or
Chimney
Forventingfollowtheguidelinesspecifiedundertheventing
section.
Gas Inlet
Electrical
Supply
Connection
Coil Plenum
Type “B” Vent
Combustible
Platform
Louver Door
Note: Line
Contact is Permissible
Furnacesinstalledwithcombustionairdrawn
fromaheatedspace which includes exhaust
fans, fireplaces, or other devices that may
produce a negative pressure should be
considered confined space installations.
WARNING:
!
Outdoor Air Using Vertical Ducts
(SeeFigure4)
If combustion air is taken from outdoors through vertical
ducts, the openings and ducts must have a minimum free
area of one square inch per 4,000 Btuh of total appliance
input.Ininstallationsdrawingcombustionairfromaventilated
attic, both air ducts must extend above the attic insulation.

G6RA, G6RK Service Manual 11
Figure 5. Equipment in a Confined Space with all
Combustion Air Drawn from the Outside
throughExterior Wall
Figure 6. Equipment in a Confined Space with All
Combustion Air Drawn from a
Crawl Space and Ventilated Attic
Figure 7. Equipment in a Confined Space with all
Combustion Air Drawn from the Outside through
Horizontal Ducts
Iftheunit isinstalledin anareawith anexhaustfan, provide
sufficient ventilation to prevent negative pressures from
occurringin the room.
The combustion air openings must not be restricted in any
manner.
Air Directly Through An Exterior Wall
(SeeFigure5)
Ifcombustionairisprovideddirectlythroughanexteriorwall,
the two openings must each have free area of at least one
square inch per 4000 Btuh of total appliance input.
OutdoorAir Using aCrawlSpace and Ventilated
Attic(SeeFigure6)
Whendirectlycommunicatingwiththeoutdoors,eachopening
shall have a minimum free area of 1 square inch per 4,000
Btuhoftotalapplianceinput.Theopeningsshallcommunicate
directly,orbyducts,withtheoutdoor spaces(crawl orattic)
that freely communicate with the outdoors.
Outdoor Air Using Horizontal Ducts (See Figure 7)
If combustion air is taken from outdoors through horizontal
ducts, the openings and ducts must have a minimum free
area of one square inch per 2,000 Btuh of total appliance
input.
Iftheunit isinstalledin anareawith anexhaustfan, provide
sufficient ventilation to prevent negative pressures from
occurringin the room.
The combustion air openings must not be restricted in any
manner.
Outlet Air Duct
must be at least
1 sq. in. per 4000
Btuh of total input
rating. Must extend
above attic insulation.
Ventilation Louvers at
each end of attic
Attic Insulation
Ventilation Louvers for
unheated crawl space Crawl Space
Inlet Air Duct must
be at least 1 sq. in.
per 4,000 Btuh of
total input rating.
Furnace
Water Heater
Vent or
Chimney
Each opening
to outside
must be at least
1 sq. in. per 2000
Btuh of total input
rating.
12" Max
12" Max
Total Input
Rating (Btu/hr)
40,000
60,000
80,000
100,000
120,000
140,000
160,000
Minimum
Free Area
(Each Opening)
20 sq. in.
30 sq. in.
40 sq. in.
50 sq. in.
60 sq. in.
70 sq. in.
80 sq. in.
Round Duct
Diameter
5"
6"
7"
8"
9"
10"
10"
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Furnace
Air Duct
Air Duct
Water Heater
Vent or
Chimney
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Do not supply combustion air from an attic
spacethat isequippedwith powerventilation
or any other device that may produce a
negative pressure.
CAUTION:
!
Each opening
to outside
must be at least
1 sq. in. per 4000
Btuh of total input
rating.
12" Max
12" Max
Total Input
Rating (Btuh)
40,000
60,000
80,000
100,000
120,000
140,000
160,000
Minimum
Free Area
(Each Opening)
10 sq. in.
15 sq. in.
20 sq. in.
25 sq. in.
30 sq. in.
35 sq. in.
40 sq. in.
Round Duct
Diameter
4"
5"
5"
6"
6"
7"
8"
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Furnace
Water Heater
Vent or
Chimney

12 G6RA, G6RK Service Manual
VENTING REQUIREMENTS
General
Thisfurnacemustbeventedincompliancewith,thecurrent
revisionoftheNationalFuelGasCode(ANSI-Z223.1/NFPA54),
withthe instructions provided below, andwith the Category
I Venting Tables provided with the furnace.
InCanada,ventingshallconform totherequirementsofthe
current(CAN/CGAB149.1or.2) installationcodes. Consult
localcodesforspecialrequirements.
This furnace must never be vented to a chimney flue
servicingafireplaceorotherappliancedesignedtoburnsolid
fuel. If the furnace vent is to be connected to a chimney
servingafireplace,thefireplacemustbesealedofffromthe
chimney.
The furnace vent, if metal, may be insulated if local codes
allow. Any part of the vent system, metal vent only, not
exposed to weather, but which are exposed to ambient
temperatures below 35° F must be insulated to prevent
condensation. All vent insulation shall be foil backed
fiberglass of one inch minimum thickness.
Category I - Common Venting
Whenanexistingfurnaceisremovedfromaventingsystem
serving other appliances, the venting system is likely to be
toolarge toproperlyvent theremaining appliances.
The following steps shall be followed with each individual
applianceconnectedtotheventingsystemplacedinoperation,
while all other appliances connected to the venting system
arenotinoperation:
(a) Seal any unused openings in the venting system.
(b)Inspecttheventingsystemforpropersizeandhorizontal
pitch, as required in the National Fuel Gas Code, (ANSI
Z223.1) or the (CAN/CGA B149 ) Installation Codes and
these instructions. Determine that there is no blockage or
restriction, leakage, corrosion or other deficiencies which
could cause an unsafe condition.
(c) In so far as is practical, close all building doors and
windows and all doors between the space in which the
appliance(s) connected to the venting system are located
andotherspacesofthebuilding. Turnonclothesdryersand
anyappliancenotconnectedtotheventingsystem. Turnon
any exhaust fans, such as range hoods and bathroom
exhausts,so theyshall operateat maximumspeed. Do not
operate a summer exhaust fan. Close fireplace dampers.
(d)Followthelightinginstructions. Placetheappliancebeing
inspectedinoperation.Adjustthermostatsoapplianceshall
operatecontinuously.
(e)Testfordrafthoodequippedappliancespillageatthedraft
hoodreliefopeningafter5minutesofmainburneroperation.
Use the flame of a match or candle.
(f)Afterithasbeendeterminedthateachapplianceconnected
totheventingsystemproperlyventswhentestedasoutlined
above,returndoors,windows,exhaustfans,fireplacedampers
andanyothergasburningappliancetotheirpreviousconditions
of use.
(g) If improper venting is observed during any of the above
tests, the venting system must be corrected.
(CategorieI)—Procedercommesuitpourchaqueappareil
raccorde a la tuyauterie d’evacuation et en etat normal de
fonctionnement; tous les autres appareils raccordes a la
memetuyauteried’evacuationdoiventetremishorsservice:
(a)sceller toute ouverture non utilisee de la tuyauterie
d’evacuation.
(b)s’assurer que la tuyauterie d’evacuation presente des
dimensions et une pente horizontale conformes a la norme
ANSIZ223.1,intituleeNationalFuelGasCodeouauxcodes
d’installation CAN/CGA-B149, ainsi qu’aux presentes
instructions. S’assurer que la tuyauterie n’est pas bloquee,
restreinte,corrodee,qu’ellenefuitpasetqu’ellenepresente
aucunautredefautpotentiellementdangereux.
(c)dans la mesure du possible, fermer toutes les portes et
fenetresdubatiment,ettouteslesportesentrelapieceouse
trouvel’appareilraccordealatuyauteried’evacuationetles
autrespiecesdubatiment. Mettreenservicelessecheuses
et tout autre appareil qui n’est pas raccorde a la tuyauterie
d’evacuation. Faire fonctionner a regime maximal tout
ventilateur d’evacuation, tel que les hottes de cuisiniere et
lesventilateursdesallesdebains. Nepasmettreenservice
les ventilateurs d’ete. Fermer les registres des foyers.
(d)respecter les instructions d’allumage. Mettre en service
l’appareilal’essai. Reglerlethermostatdemaniereaceque
l’appareilfonctionnesansinterruption.
(e)s’assurerqu’unappareilmunid’uncoupe-tiragenepresente
aucunefuiteal’ouvertureducoupe-tirageapresquelebruleur
principal ait fonctionne pendant cinq minutes. Employer la
flammed’uneallumetteoud’unechandelle.
(f)apresavoir determineque tousles appareilsraccordes a
la tuyauterie d’evacuation evacuent correctement tel que
prescrit ci-dessus, rouvrir les portes at les fenetres et
remettrelesventilateursd’evacuation,lesregistresdefoyers
et tout autre appareil fonctionnant au gaz a leur etat de
fonctionnementinitial.
(g)siunappareiln’evacuepascorrectementalasuitedel’un
des essais ci dessus, corriger la tuyauterie d’evacuation.

G6RA, G6RK Service Manual 13
Cover
Plate
Nut
Covered Vent
Collar Hole
Looking Down at
Vent Opening
Figure 8. G6RA Bleed Tube Installation
Figure 9. G6RA Vent Collar Detail
Theventingsystemshouldbedesignedtohavetheminimum
number of elbows or turns. All horizontal runs shall be
sloped upwards fromthefurnaceat1/4inchperrunningfoot
of vent. Supports for the vent pipe must be installed a
minimum of every five feet along the vent run to ensure no
displacementafterinstallation.
Undernocircumstancesshallanyportionoftheventsystem
extend into or pass through any return air duct, supply air
duct, or plenum.
Ifthe furnaceis operated withblocked orrestricted venting,
the blocked vent switch located in the vent plate will open,
turning off the gas supply to the burners. The blocked vent
switchis a manually resetdevice. DO NOT install ajumper
wireacrossthis switchto defeatitsfunction. DO NOTreset
theswitchwithoutidentifyingandcorrectingthefaultcondition
which caused the switch to trip. If this switch must be
replaced, use only the part specified in the Replacement
Parts List.
Category III - Horizontal Venting
NOTE:ThereducedNOxmodels(eighthcharacterN)arenot
approvedasaCategoryIII(CategorieIII)furnaceforusewith
horizontalventing.
The furnacesareapprovedforusewith3"singlewallAL29-
4C stainless steel vent pipe in horizontal vent applications.
This pipe is available from the following manufacturers:
Z-FLEX Inc. - vent brand name (Z-VENT)
Heat-fabInc.-ventbrandname(Saf-T Vent)
Flex-LInternational -ventbrandname(Star-34Vent)
Thisvent pipe must beused for the entirelengthof the vent
run.Theinstallationmustbeinaccordancewithallinstructions
supplied by the vent manufacturer for use on Category III
appliances. Whenventing horizontallythisis aCategory III
furnace, the vent pressure is positive, and the venting
system must be sealed.
ForhorizontalventinginstallationsinboththeUnitedStates
and Canada the transition assembly must be modified, the
bleed tube must be added to the pressure switch tube, and
theventswitchmustbeby-passed. Thebleedtubeisfound
in an envelope, attached to the furnace literature.
HorizontalVentingForG6RAModels:
NOTE:Anoptionalhorizontalventkitwillberequired.See
Vent Kit Bleed Tube Chart on Page 40.
1. Remove the rubber tubing from the pressure switch
sensortubeandthecollectorpan sensortube. Cut1/2
inchfromoneendoftherubbersensortube,foldinhalf
and cut along the bend line. Discard the 1/2 inch long
pieceandplacetheothertwopiecesonbothendsofthe
bleedtube,donotcovertheholeinthebleedtube. Place
theassembly backon thepressure switchsensor tube
and the collector pan sensor tube.
(SeeFigure8.)
2. Removethenutandrestrictorplatefromtheventcollar
assemblyanddiscardtherestrictor plate. Removethe
cover plate from the envelope attached to the furnace
literature,andfittheclearanceholeover theweldstud.
Thecoverplatemustcoverthehole(s)ontheventcollar
assembly. Tighten the nut securely while holding the
cover plate in position. (See Figure 9.)
3. Bypass the vent switch by removing both wires from
the vent switch and attaching them to the wire nut.
(SeeFigure10.)
HorizontalVentingForG6RKModels:
NOTE:Anoptionalhorizontalventkitwillberequired.See
Vent Kit Bleed Tube Chart on Page 40.
Collector
Pan
Pressure
Switch
Cut
Sensor
Tubes Bleed Tube
Bleed Tube
Orifice
WARNING:
Upon completion of the furnace installation,
carefully inspect the entire flue system both
inside and outside the furnace to assure it is
properlysealed. Leaksinthefluesystemcan
resultinseriouspersonalinjuryordeathdue
to exposure of flue products, including
carbon monoxide.
!

14 G6RA, G6RK Service Manual
Figure 10. Limit Circuit Wiring
Bleed Tube
Bleed Tube
Orifice
Collector
Pan
Pressure
Switch
Transition
Inducer
Remove
and
Discard
Figure 13. G6RK Reducer Installation
Figure 12. G6RK Horizontal Vent Modification
Figure 11. G6RK Bleed Tube Installation
Combustion
Tube
Screw
Restrictor
Plate
Transition
4" to 3" Reducer
Special 3"
AL29-4C
Stainless Steel
Vent Pipe
Wire Nut
Switch
Limit Switch Flame
Roll-Out
Switch
Vent
Limit
Blue
Blue
1. By-pass the vent switch, located on blower
compartment door, by removing both wires from the
switch. Remove wire terminals, strip wires and tie
together in a wire nut. (See Figure 11.)
2. Remove the rubber tubing from the pressure switch
sensortubeandthecollectorpansensortube. Cutthe
tubing approximately 3" from one end and insert the
bleed tube into the tubing. Do not cover the hole in
the bleed tube. Place the tubing assembly back on
the pressure switch sensor tube and collector pan
sensortube.(See Figure11.)
3. To gain access to the restrictor plate, remove and
discard the combustion tube from the transition
assembly. Insure the seal between inducer and
transitionassemblyisnotbroken.(SeeFigure12.)
4. Remove and discard the restrictor plate and screw
from the transition assembly. (See Figure 12.)
5. Installandseala4"to3"reducertothetransition.(See
Figure13.) Attachthenewhightemperatureventpipe
tothe reducer.
The components of the horizontal vent system must not be
penetrated,withscrews,rivets,orotherdevices,eitherwhen
joining pipes and fittings or using support straps. All joints
mustbesealedwithhightemperaturesiliconebeforelocking

G6RA, G6RK Service Manual 15
CAUTION:
Do not drill holes through the vent pipe or
fittingsonahorizontallyventedfurnace.Donot
use sheet metal screws, or rivets. Drilling,
screws, or rivets will cause leaks.
Figure 14. Typical Horizontal Vent Installation
Furnace Pipe Reducer Maximum Max. Feet
Model Number Size Needed # Elbows Vent Pipe
G6RA045C-08 3" None 4 35
G6RA060C-12 3" 4" to 3" 4 35
G6RA072C-12 3" 4" to 3" 4 35
G6RA096C-16 3" 4" to 3" 4 35
G6RA096C-20 3" 4" to 3" 4 35
G6RA120C-16 3" 4" to 3" 4 35
G6RA120C-20 3" 4" to 3" 4 35
G6RA144C-20 3" *4" to 3" 3 30
G6RK060C-12 3" 4" to 3" 4 35
G6RK072C-12 3" 4" to 3" 4 35
G6RK072C-16 3" 4" to 3" 4 35
G6RK096C-12 3" 4" to 3" 4 35
G6RK096C-16 3" 4" to 3" 4 35
G6RK120C-20 3" 4" to 3" 4 35
Note: Special 5" to 4" Reducer Kit, p/n 902249 required for model
number G6RA144C-20.
Table 4. Horizontal Venting Requirements
HorizontalVenting (Thru-the-Wall)
Venting Requirements
!
bands are installed. If the lengths of pipe must be cut, the
joint must still be sealed with silicone and the locking band
used. When installing the condensate tube be sure to form
atrapbymeansofa3"loopfilledwithwater.(SeeFigure14.)
Keep the number of pipe fittings to a minimum. Maintain a
minimum of 6 inches of air space between the vent and
combustiblesatalltimes,thisincludesinsideandoutsidethe
building.
NOTE: Thedirectionofthemale-femalejointsfromthedrain
tee to the termination tee is opposite to standard gas
applianceventing. Themaleendofthe pipespointtowards
thefurnace.
1. Applyanadhesivebeadaroundtheoutsideofthepipe
approximately 1/4" from the end of the pipe. This
includesthefirstfittingorpipeattachedtothefurnace.
2. Push the pipe and fitting together while twisting the
pipe or fitting. Twisting the pipe or fitting spreads the
adhesive completely within the fitting socket.
3. When the pipe is at the socket bottom, inspect the
joint.Lookforacomplete,uninterruptedringofadhesive
materialaroundthepipeatthefittingsocket. Additional
adhesive or rotation of the pipe or fitting may be
requiredforacompleteseal. Thecompleteadhesive
materialringprovidesthesealrequiredforthepositive
pressurevent.
4. Allventsystemsmustinclude ateeanddrainplugfor
collectionanddisposal of condensate. The drain tee
must be installed within the first 5 feet of vent run to
protectthe furnace.
5. All horizontal sections must have a slope toward the
drain tee of not less than 1/4" per foot to prevent the
collectionofcondensate at any location other thanat
the tee.
6. Horizontalrunsmustbesupportedwith3/4"pipestrap
at a maximum of 5 foot intervals and at each point
wherean elbow isused.
7. Maintaina6 inchminimum airspaceto combustibles
from all sections of the stainless steel vent system,
except when a wall thimble is used.
Through-The-Wall Power Venting — The Tjerlund GPAK-
1TN through-wall kit is certified for use with G(-) Series
furnaces. The kit includes a power venter, a side-wall vent
hood and a barometric draft control. It has an electrical
interlocktoassurethatthefurnacewillnotoperatewhenthe
power venter is off.
The kit is for use only when exhaust is through an exterior
wall,normallywith horizontalventpiping. Thepowerventer
establishes negative pressure in the vent piping and the
furnace operates as if connected to Category I vertical
venting.
InstallationInstructionsareprovidedwiththekit.Installation
must conform to those instructions and applicable
requirementsoflocal codes.
90 ˚ Elbow
3" Dia. Loop Outside
Wall
Wall Thimble
(For combustible
wall material)
Termination
Tee
Support
Tee
0-6' Drain
Plug
1
/ 4 " Per
Foot Rise
Locking Band Locking
Band

16 G6RA, G6RK Service Manual
4 ft. min
4 ft. min
12 in. min
Mechanical
draft vent
terminal
Mechanical
draft vent
terminal
Forced
Air Inlet
Grade
Less
than 10 ft.
3 ft. min.
FlexibleVentSystems
WARNING:
The entire vent system must be sealed with
a high temperature sealant which will
withstand temperatures of 450°F.
Recommended sealants: Dow Corning
Sealant 736 RTV; GE 106 RTV; High Tech
Ind., High TEMP RED.
!
LocationofOutdoorTerminations
HorizontalInstallation
The vent termination tee must be installed with the
followingminimum clearances. (SeeFigure 15.)
Figure 16. Alternate Horizontal Vent Installation
1. The termination tee must be 12 inches above snow
levelorgradelevelwhicheverishigher.SeeFigure16
foralternatemethodtoachieve12"abovesnowlevel.
2. The minimum distance from any door, (openable)
window,orgravityairinletis4ft.below,4ft.horizontally,
or 1 ft. above.
3. Theventterminationshallbeaminimumof3ft.above
any forced air inlet within 10 ft. (See Figure 15.)
4. Recommendedminimumdistancefromaninsidecorner
formedbytwoexteriorwallsis6ft.,butisnotrequired.
5. Theminimumdistancefromgasorelectricmeter(s)is
4 ft.
6. Avoidareaswherecondensatedrainagemaycause
problemssuchasaboveplanters,patios,oradjacent
to windows where the steam from the flue gases
may cause fogging. Do not terminate above any
publicwalkway.
7. Selectthepointofwallpenetrationwheretheminimum
1/4inchperfootofupwardslopecanbemaintained.
8. When penetrating a noncombustible wall, the hole
throughthewallmustbelargeenoughtomaintainthe
pitch, pipe clearance for passage, and provide for
proper sealing. Penetrating a combustible wall
requirestheuseofawallthimble.(SeeFigure22.) A
6-1/2inchsquareframedopeningisrequiredtoinsert
the thimble halves. The thimble is adjustable to
varying wall thickness and is held in place by
applyingsealanttothemalesleevebeforeassembly.
Also run a bead of sealant around the outer wall
thimble.
9. Theventpipemustextend1-1/4inchesthroughthe
outerthimblehalfforacombustiblewall. Besureto
check this carefully before cutting the vent pipe.
10. Attach a 3 inch coupling to the end of the pipe that
extends through the wall or thimble. This prevents
thevent pipefrom being pushedinward.
11. Cut an 8 inch minimum piece of vent pipe and
connect the coupling to the termination tee. The
inside of the tee must be a minimum of 12 inches
from the outside of the wall. (See Figure 17.)
Figure 15. Vent Termination Clearances
Use Wall Thimble at
Vent Points
Support
Ground Level
Termination Tee

G6RA, G6RK Service Manual 17
Wall Thimble
(Inner Half)
Inner Shield
4
1
/ 2 " Dia.
Wall Thimble Outer Half
Outer Overlapping
Shield 6
1
/ 2 " Dia.
3" Termination
Tee
Protective
Screen
Inside
Combustible
Wall
Inside
Combustible
Wall
3" Vent
Pipe
Outside
Combustible
Wall
Inner
Overlapping
Shield 6
3
/ 8 " Dia.
Locking Band
12" Min
Figure 17. Typical Termination
Flexiblegas vent is approvedfor use in verticalsingle vent
orcommonventinstallationsonly. Theminimumdistanceto
combustiblesis1"fortypeBinsulatedand6"forsinglewall.
Theventingsystemmustbeinstalledinaccordancewiththe
localauthorities,theventmanufacturer'sinstructionsandthe
instructions listed below.
The flexible vent must be installed in accordance with the
ventingtablesforverticalorcommonventingonly. Thevent
system must be supported in horizontal runs with
3/4"pipestrapatamaximumof5footintervals.Allhorizontal
sections must have a slope toward the furnace of not less
than1/4"perfoot. Theventmustnotsag,orhaveanybends
greaterthan90degrees.
Leak Check
Afterthegaspipingtothefurnaceiscomplete,allconnections
must be tested for gas leaks. To check for leaks use only a
soapandwatersolutionorotherapprovedmethod.
NOTE: When pressure testing gas supply lines at
pressuresgreaterthan1/2psig(14in.watercolumn),the
furnace must be disconnected from the gas supply
piping system to prevent damage to the gas control
valve.
Ifthetestpressureislessthanorequalto1/2psig(14in.
watercolumn),thefurnacemustbeisolatedfromthegas
supply line by closing off the main shut-off valve.
ELECTRICAL WIRING
General
Electricalconnections mustbe made inaccordance withall
applicablelocalcodesandordinances,andwiththecurrent
revision of the National Electric Code (ANSI/NFPA 70).
For Canadian installations electrical connections and
grounding must be done in accordance with the current
Canadian Electrical Code (CSA C22.1 Part 1) and/or local
codes.Ifanyoftheoriginalwireassuppliedwiththefurnace
must be replaced, it must be replaced with wire having a
minimum temperature rating of 105oC. Refer to the furnace
nameplateandTable7for electricalrequirements.
SYSTEM OPERATION INFORMATION
General
Proper maintenance is most important to achieve the best
performance from a furnace. Follow these instructions for
years of safe, trouble free operation.
Do not place combustible material on or against
the furnace cabinet or the vent pipe.
Do not store gasoline or any other flammable
vapors and liquids in the vicinity of the furnace.
Change or replace the air filters monthly during
anyperiodwhenthecirculatingblowerisoperating
regularly.
Always replace the doors on the furnace after
servicing. Do not operate the furnace without all
doors and covers in place.
Avoid operating the furnace when windows and
doors are open.
Be sure that the thermostat is properly installed
and is not being affected by drafts or heat from
lamps or other appliances.
Sequence of Operation
Operatingsequencesfortheheating,cooling,andfanoperation
aredescribedbelow.Refertothewiringdiagrams(Figure22,
Page22&Figure23,Page23)andthelowvoltagefieldwiring
diagram(Figure28,Page25).
HeatingMode:
1. Onacallforheatthermostatcloses,applying24VACto
the W terminal on the control board.
2. The control board checks for continuity on the 24 VAC
limitcontrolcircuit(over-temperaturelimitswitch,flame
roll out switches and blocked vent switch). If an open
limit is detected the control board will energize the
inducerandtheconditionedairblower.Allothersystem
functions will be inoperable until the limit circuit closes.
Whilethelimitisopen,theredLEDwillpulseatarateof
oneblink.
3. The furnace control checks for continuity across the
pressure switch (24 VAC). If the pressure switch is
closed the heat mode sequence will not continue. If it
remains closed for 10 seconds the red LED will blink 3
times repetitively until the fault condition clears.
4. Theinducerisenergized.
5. The pressure switch will close. If the pressure switch
does not close after 10 seconds the fault LED will blink
2 times repetitively and the inducer will continue to run
until the switch is closed.
6. The inducer will pre-purge for 30 seconds and then the
ignitor will start its warm-up. After 30 seconds of ignitor
warm-up the gas valve (24 VAC) will open. The ignitor
circuitstaysenergizedfor6secondsafterthegasvalve
opens.

18 G6RA, G6RK Service Manual
7. The furnace control must prove flame via the flame
sensor six seconds after the gas valve opens. If flame
is sensed, all burners are on and the ignitor cools off. If
no flame is sensed, the gas valve closes immediately
and the inducer continues to run. A second trial for
ignition(step6)beginsifnoflameissensed.Onthefifth
try for ignition, the furnace control is locked out and the
red LED will blink 4 times repetitively. The thermostat
must be opened for at least ten seconds to reset the
furnace control after a lock out. Otherwise, the furnace
willattemptanotherignition sequence in 1 hour.
8. Thefurnacecontrolenergizesthecirculating airblower
on the heating speed 30 seconds after the gas valve
circuit is energized.
9. Whenthethermostathasbeensatisfied,gasvalveisde-
energized.
Fan Mode:
1. On a call for fan operation, the thermostat applies 24
VAC to the G terminal on the furnace control board.
2. The circulating air blower is energized immediately on
theheatingspeed.
3. Ifthefurnaceisoperatedin thecontinuous ONposition
at the thermostat and is then switched to AUTO, the
circulating blower will operate for a specified delay
(factory set at 120 seconds).
Furnace Fails to Operate
If the furnace does not operate check the following:
1. Isthethermostatoperatingproperly?
2. Aretheblowercompartmentdoor(s)inplace?
3. Is the furnace disconnect closed?
4. Hasthecircuitbreaker trippedorthe controlboardfuse
burnedopen?
5. Is the gas turned on?
6. Arethere any manual reset switches open?
7. Is the filter dirty or plugged?
8. Is the flame sensor coated? (Remove and clean with
steelwool.)
Ifthefurnace locks out after 5 attempts for ignition, itwilltry
againeveryhourifacallforheatremains.Iftheinducerand
circulating air blowers are operating, and items 1 through 8
have been checked, press the red reset button on the vent
safety switch. (See Figure 19.) If the furnace operates after
depressingtheresetbutton,contacta qualifiedserviceman
toidentify and repair the problem.
Ifthefurnacecontinuestonotoperate,depresstheredreset
buttononthe flame roll out switches. (See Figure 19.) Ifthe
furnaceoperatesafterdepressingtheresetbuttons,contact
a qualified serviceman to identify and repair the problem.
Twinning of Two Furnaces
ThecontrolboardonaG6seriesfurnaceiscapableofbeing
twinnedtoanotherG6furnace.Thethermostatwiresandthe
3/16 inch quick-connect terminals marked "TWIN" on the
furnace controls must be connected together for twinning.
(SeeFigure18.)
NOTE:Componentsarelistedinorderofsequence
of operation.
10. The inducer is de-energized after a 30 second post
purge.
11. The furnace control keeps the circulating air blower
energizedfor 120second (factoryset) or 60,90, or180
seconds(fieldadjustable).(SeeFigure21.)
12. Abnormal conditions: If a limit opens during operation,
theinducerandcirculatingairblowercontinuetooperate.
Thegasvalveisde-energizedimmediately.Theblowers
continueto operateuntil thelimit closes. Whenthe limit
closes the induced draft motor will run through post
purge.Thecirculatingairblowercontinuestooperatefor
the specified delay (factory set at 120 seconds).
CoolingMode:
1. On a call for cooling the thermostat closes, applying 24
VACtotheGandYterminalsonthefurnacecontrol.This
closes the compressor contactor.
2. Thefurnacecontrolenergizesthecirculatingblower(115
VAC) on the cooling speed.
3. Whenthethermostatis satisfied,theGandYterminals
on the control board are de-energized opening the
compressorcontactor.
4. The circulating air blower is de-energized after a 90
seconddelay.
CAUTION:
!
Label all wires prior to disconnection when
servicing controls. Wiring errors can cause
improper and dangerous operation.
Verify proper operation after servicing.
CAUTION:
!
Do not use matches, lighters, candles or other
sources of open flame to check for gas leaks.