25
bined gas furnace and heat pump installation which uses an out-
door temperature sensor to determine the most cost efficient
means of heating (heat pump or gas furnace).
Strictly follow the wiring guidelines in the fossil fuel kit installation
instructions. All furnace connections must be made to the furnace
two-stage integrated control module and the “FURNACE” terminal
strip on the fossil fuel control board.
G
AS
S
UPPLY
AND
P
IPING
Natural Gas
Minimum: 4.5" w.c.
Maximum: 10.0" w.c.
Propane Gas
Minimum: 11.0" w.c.
Maximum: 13.0" w.c.
INLET GAS SUPPLY PRESSURE
The furnace rating plate includes the approved furnace gas input
rating and gas types. The furnace must be equipped to operate
on the type of gas applied. This includes any conversion kits
required for alternate fuels and/or high altitude.
Inlet gas supply pressures must be maintained within the ranges
specified in the following table. The supply pressure must be con-
stant and available with all other household gas fired appliances
operating. The minimum gas supply pressure must be maintained
to prevent unreliable ignition. The maximum must not be ex-
ceeded to prevent unit overfiring.
H
IGH
A
LTITUDE
D
ERATE
When this furnace is installed at high altitude, the appropriate
High Altitude orifice kit must be applied. This is required due to
the natural reduction in the density of both the gas fuel and com-
bustion air as altitude increases. The kit will provide the proper
design certified input rate within the specified altitude range.
High altitude kits are purchased according to the installation alti-
tude and usage of either natural or propane gas. Consult the
furnace Specification Sheet for appropriate kits.
Do
not
derate the furnace by adjusting the manifold pressure to a lower pressure than specified on the furnace rating plate. The
combination of the lower air density and a lower manifold pressure will prohibit the burner orifice from drawing the proper amount of
air into the burner. This may cause incomplete combustion, flashback, and possible yellow tipping.
In some areas the gas supplier may artificially derate the gas in an effort to compensate for the effects of altitude. If the gas is
artificially derated, the appropriate orifice size must be determined based upon the BTU/ft
3
content of the derated gas and the
altitude. Refer to the National Fuel Gas Code, NFPA 54/ANSI Z223.1, and information provided by the gas supplier to determine the
proper orifice size.
A different pressure switch may be required at high altitude regardless of the BTU/ft
3
content of the fuel used. Consult the furnace
Specification Sheet for pressure switch.
P
ROPANE
G
AS
C
ONVERSION
This unit is configured for natural gas. To operate this furnace on L.P. gas, an LPM-07 LP Conversion kit must be used.
The indicated kit must be used to insure safe and proper furnace operation. All conversions must be performed by a qualified installer,
or service agency.
G
AS
V
ALVE
This unit is equipped with a 24 volt gas valve controlled during furnace operation by the integrated control module. As shipped, the
valve is configured for natural gas. The valve is field convertible for use with propane gas by replacing the regulator spring with a
W
IRE
ROUTING
MUST
NOT
INTERFERE
WITH
CIRCULATOR
BLOWER
OPERATION
,
FILTER
REMOVAL
OR
ROUTINE
MAINTENANCE
.
IMPORTANT NOTE
Figure 30
R
Y
C
Furnace Integrated
Control Module
Remote Condensing Unit
(Single-Stage Cooling)
R
Room
Thermostat
T
O
PREVENT
UNRELIABLE
OPERATION
OR
EQUIPMENT
DAMAGE
,
THE
GAS
MANIFOLD
PRESSURE
MUST
BE
AS
SPECIFIED
ON
THE
UNIT
RATING
PLATE
. O
NLY
MINOR
ADJUSTMENTS
SHOULD
BE
MADE
BY
ADJUSTING
THE
GAS
VALVE
PRESSURE
REGULATOR
.
CAUTION
HIGH VOLTAGE !
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
DUE
TO
ELECTRICAL
SHOCK
,
DISCONNECT
ELECTRICAL
POWER
BEFORE
SERVICING
OR
CHANGING
ANY
ELECTRICAL
WIRING
.
WARNING
