Lennox MERIT ML180UHE Installation Instructions Manual page 14

HORIZONTAL LEFT POSITION
Top Vent Discharge
Vent Pipe
Pressure
Switch
Flue
Transition
Cover Plate
Make−Up Box
D Disconnect pressure switch hose from barbed fitting on the
pressure switch assembly. Remove pressure switch assembly
(1 screw) and cut wire tie to free pressure switch wires. Re−
install pressure switch on the other side of orifice plate and re−
connect pressure switch hose.
D Re−secure pressure switch wires: Either pull excess wires
through the blower compartment and secure using supplied
wire tie, or coil excess wire and secure to the gas manifold.
FIGURE 19
HORIZONTAL LEFT POSITION
Side Vent Discharge
Pressure Switch
Vent Pipe
Make−Up Box
D Cut combustion air inducer tubing from 9" to 7" to avoid inter-
ference with inducer motor
D Disconnect pressure switch hose from barbed fitting on the
pressure switch assembly. Remove pressure switch assembly
(1 screw) and cut wire tie to free pressure switch wires. Re−
install pressure switch on the other side of orifice plate and re−
connect pressure switch hose.
D Re−secure pressure switch wires: Either pull excess wires
through the blower compartment and secure using supplied
wire tie, or coil excess wire and secure to the gas manifold.
FIGURE 20
AIR
FLOW
Collector Box
AIR
Make−Up Box
FLOW
Collector Box
Page 14
HORIZONTAL RIGHT POSITION
Top Vent Discharge
Vent Pipe
Flue
Transition
AIR
FLOW
D Gas supply piping must be brought into the unit from the bot-
tom in order to accommodate the flue pipe.
D Cut combustion air inducer tubing from 9" to 8" to avoid inter-
ference with inducer motor
D Remove make−up box assembly (2 screws) and cut wire tie to
free make−up box wires. Re−install make−up box on other side
of cabinet.
D Re−secure make−up box wires: Either pull excess wires through
the blower compartment and secure using supplied wire tie, or
coil excess wire and secure to the gas manifold.
FIGURE 21
HORIZONTAL RIGHT POSITION
Side Vent Discharge − no modifications necessary
AIR
FLOW
FIGURE 22
Pressure Switch
Cover Plate
Collector Box
Make−Up Box
Pressure Switch
Vent Pipe
Flue Transition
Collector Box