Lennox part number 56J18). Position the support frame on top of the blocks and install the unit on the frame. Leave 5−1/2 inches for service clearance for condensate trap.
3 − Route auxiliary drain line so that water draining from this outlet will be easily noticed by the homeowner. If necessary, run the condensate line into a condensate pump to meet drain line slope requirements. The pump must be rated for use with condensing furnaces. Protect the condensate discharge line from the pump to the outside to avoid freezing.
4 − Set unit in drain pan as shown in figure 19. Leave 5−1/2 inches for service clearance below unit for condensate trap.
5 − Continue with exhaust, condensate and intake piping installation according to instructions.
Unit Heater Discharge Duct Guidelines
A field−fabricated and installed discharge air duct and grille cabinet is suitable for use with the G61MP heater. Keep the following items in mind when constructing the cabinet.
1 − Outer dimensions of cabinet should match those of the unit heater, so the duct/grille cabinet installs flush with the unit heater cabinet. See figure 20.
2 − Flange both ends of duct/grille cabinet so that screws can be used to secure cabinet to discharge end of unit heater.
3 − To ensure proper operation, the duct/grille cabinet must be at least 18 inches long.
4 − Use #10−16 x 1/2 inch sheet metal screws to secure duct/grille cabinet to unit, taking care not to damage in- ternal components of unit heater when drilling holes or installing screws. See figure 20.
INTAKE PIPE
*Gas connector may be used for Canadian installation if accept- able by local authority having jurisdiction.
EXHAUST PIPE
*GAS
CONNECTOR
5 − Use adjustable, double−deflection grille(s) to distribute discharge air. Adjust static pressure to be in the 0.06 inch to 0.10 inch w.c. range.
18in.
MIN.
RAISED
PLATFORM
CONDENSATE LINE
SERVICE PLATFORM
FIGURE 19
G61MP Installed in Unit Heater Applications
The G61MP may also be installed as a unit heater. Either suspend the furnace from roof rafters or floor joists, as shown in figure 18, or install the furnace on a field−fabri- cated raised platform, as shown in figure 19. The unit must be supported at both ends and beneath the blower deck to prevent sagging. The condensate trap must be installed where it can be serviced at a later date.
DRAIN PAN (to protect finished space) 
NOTE − When installing duct/grille cabinet, take care not to damage internal unit
heater components when drilling holes or installing screws.
FIGURE 20
Return Air −− Horizontal Applications
Return air may be brought in only through the end of a fur- nace installed in the horizontal position. The furnace is equipped with a removable bottom panel to facilitate installation. See figure 11.
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