Lennox ML180UHA Installation Instructions Manual page 13

UPFLOW POSITION
Right Side Vent Discharge
Cover Plate
Collector Box
Pressure
Switch
AIR
D Cut combustion air inducer tubing from 229 mm ( 9" ) to 127 mm
(5") to avoid interference with inducer motor
FIGURE 16
HORIZONTAL LEFT POSITION
Top Vent Discharge
Vent Pipe
Pressure
Switch
Flue
Transition
Cover Plate
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 17
Flue Transition
Vent Pipe
FLOW
AIR
FLOW
Collector Box
HORIZONTAL LEFT POSITION
Pressure Switch
Vent Pipe
Make-Up Box
D Cut combustion air inducer tubing from 227 mm (9") to
178 mm (7") to avoid interference 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.
HORIZONTAL RIGHT POSITION
Vent Pipe
Flue
Transition
AIR
FLOW
D Gas supply piping must be brought into the unit from the
bottom in order to accommodate the flue pipe.
D Cut combustion air inducer tubing from 227 mm (9") to 203
mm (8") to avoid interference with inducer motor
Page 13
Side Vent Discharge
Collector Box
FIGURE 18
Top Vent Discharge
Pressure Switch
FIGURE 19
AIR
FLOW
Cover Plate
Collector Box