26
INSTALLATION CONSIDERATIONS
Option 2
The internal vent pipe and elbow may be removed from the
furnace to permit the vent to exit the top (original side) of
the furnace. If this option is used, an RF000142 Vent-Drain
coupling must be used to keep condensate from collecting
in the inducer assembly.
To install the drain, refer to the following instructions and
illustration.
COMBUSTION AIR INTAKE PIPE OPTIONS:
The RF000142 coupling can be secured directly to the
furnace intake coupling if condensation is occurring in the
combustion air inlet pipe. If the RF000142 is used on the
combustion air inlet, it must be installed with the arrow
pointing up. It should be noted, the combustion air will
actually be moving in a direction opposite of the arrow on
the RF000142 coupling.
Alternatively a tee may be used in the combustion air in-
take pipe for the same purpose. If either option is used,
a field supplied trapped drain tube, free-draining to proper
condensate disposal location must be present. A loop in the
drain tube can serve as a trap. The unused RF000142 drain
fitting should be capped.
1. Remove screws from vent flange.
2. Remove internal elbow and vent pipe.
3. Cut pipe 2 1/2" from flange.
4. Remove cabinet plug adjacent to inducer outlet and
install an original cabinet vent hole.
5. Install RF000142 coupling on inducer outlet.
6. Install flanged vent section removed in step 2 and se-
cure with clamps.
7. Secure flange to cabinet using screws removed in step
1.
Insert flange. Cut 2 ½” long.
R 000142
F
GAS SUPPLY AND PIPING
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 con-
version kits required for alternate fuels and/or high altitude.
CAUTION
T
O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE, THE INLET
GAS SUPPLY PRESSURE MUST BE AS SPECIFIED ON THE UNIT RATING PLATE
WITH ALL OTHER HOUSEHOLD GAS FIRED APPLIANCES OPERATING.
Inlet gas supply pressures must be maintained within the
ranges specified below. The supply pressure must be con-
stant and available with all other household gas fired appli-
ances operating. The minimum gas supply pressure must
be maintained to prevent unreliable ignition. The maximum
must not be exceeded to prevent unit overfiring.
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
HIGH ALTITUDE DERATE
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 combustion 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
altitude and usage of either natural or propane gas. Refer
to the product Specification Sheet or the Accessory Matrix in
this Manual for a tabular listing of appropriate altitude ranges
and corresponding manufacturer’s high altitude (Natural,
Propane gas, and/or Pressure Switch) 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 prop-
er 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
