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 4³⁄₄" (12.1 cm) 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 avoid condensate from freezing.
Leveling ensures proper condensate drainage from the heat
exchanger and induced draft blower. For proper flue pipe
drainage, the furnace must be level lengthwise from end to end.
The furnace should also be level from back to front, or have a
slight tilt with the access doors sloping downward ³⁄₄" (1.9 cm)
lower than the back panel. The slight tilt allows the heat
exchanger condensate, generated in the recuperator coil, to flow
forward to the recuperator coil front cover.
Alternate Vent/Flue Connections
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 discharge. 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” illustrations for further
details. The standard piping connections may also be used in
these positions. See “Vent/Flue Pipe and Combustion Air Pipe”
for details concerning the conversion to the alternate vent/flue
and combustion air connections.
When using the horizontal alternate vent configuration, you must
use the RF000142 vent drain kit. See “Alternate Flue/Vent
NOTE: Alternate vertical piping connections cannot be used
when an upflow furnace is installed with the supply air
discharging to the right, or when a counterflow furnace is
installed with the supply air discharging to the left. In either case,
use the standard flue and combustion air piping connections.
Alternate Flue/Vent Location
C. Field supplied drain hose
The field supplied drain hose is connected from the vent/
drain connection to the condensate drain line with a field
Make a small loop in the drain hose to serve as a P-trap.