House depressurization can cause back drafting or improper
combustion of gas-fired appliances, thereby exposing build-
ing occupants to gas combustion products that could include
If this furnace is to be installed in the same space with other
gas appliances, such as a water heater, ensure there is an ad-
equate supply of combustion and ventilation air for the other
appliances. Refer to the latest edition of the National Fuel
Gas Code NFPA 54/ANSI Z223.1 or CAN/CSA B1491-15 Instal-
lation Codes or applicable provisions of the local building
codes for determining the combustion air requirements for
Most homes will require outside air be supplied to the fur-
nace area by means of ventilation grilles or ducts connecting
directly to the outdoors or spaces open to the outdoors such
as attics or crawl spaces.
This furnace may be installed in an upright position or hor-
izontal on either the left or right side panel. Do not install
this furnace on its back. For upright upflow furnaces, return
air ductwork may be attached to the side panel(s) and/
or basepan. For horizontal upflow furnaces, return air
ductwork must be attached to the basepan. For both up-
right or horizontal counterflow furnaces, return ductwork
must be attached to the basepan (top end of the blower
compartment). NOTE: Ductwork must never be attached
to the back of the furnace. Contact your distributor for
proper airflow requirements and number of required
ductwork connections. Refer to "Recommended Installa-
tion Positions" figure for appropriate installation positions,
ductwork connections, and resulting airflow arrangements.
Horizontal Applications & Considerations
2" 2" 3/8"
When installing a furnace horizontally, additional consideration
must be given to the following:
If suspending the furnace from rafters or joists, use 3/8" thread-
ed rod and 2"x2"x1/8" angle iron as shown in the following
diagram. The length of rod will depend on the application
and the clearances necessary.
If the furnace is installed in a crawl space it must be sus-
pended from the floor joist or supported by a concrete pad.
Never install the furnace on the ground or allow it to be
exposed to water.
Front Cover Pressure Switch Tube Location
When a furnace is installed horizontally with left side down,
the front cover pressure switch tube must be re-located to
the lower port of the collector box cover.
1. Remove tube from front cover pressure switch and
collector box cover.
2. Remove rubber plug from bottom collector box port
and install on top collector box port.
3. Locate 24" x 1/4" tube in bag assembly.
4. Install one end on front cover pressure switch.
5. Route tube to lower port on collector box cover and
cut off excess tubing.
Drain Trap and Lines
In horizontal applications the condensate drain trap is secured
to the furnace side panel, suspending it below the furnace.
A minimum clearance of 5.5" below the furnace must be
provided for the drain trap. Additionally, the appropriate
downward piping slope must be maintained from the drain
trap to the drain location. Refer to Condensate Drain Trap
and Lines for further details. If the drain trap and drain line
will be exposed to temperatures near or below freezing,
adequate measures must be taken to prevent condensate
Leveling ensures proper condensate drainage from the heat
exchanger. For proper flue pipe drainage, the furnace must
be level lengthwise from end to end. The furnace should
have a slight tilt from back to front with the access doors
downhill from the back panel approximately 1/2 to 3/4
inches. The slight tilt allows the heat exchanger condensate,
generated in the recuperator coil, to flow forward to the recu-
perator coil front cover.
Alternate Vent/Flue and Combustion Air Con-
In horizontal installations provisions for alternate flue and
combustion air piping are available for upflow furnaces with
left discharge and counterflow furnaces with right air dis-
charge. This configuration allows the flue and combustion air
piping to be run vertically through the side of the furnace.
Refer to the "Recommended Installation Positions" figure
for further detail. The standard piping connections may
also be used in these positions. Refer to Vent/Flue Pipe and