Lennox International Inc Gas Units, G61MP Series Units installation instructions

17 − Remove the primary limit from the vestibule panel.

18 − Remove two screws from the front cabinet flange at the blower deck. Spread cabinet sides slightly to allow clearance for removal of heat exchanger.

19 − Remove screws along vestibule sides and bottom which secure vestibule panel and heat exchanger as- sembly to cabinet. Remove two screws from blower rail which secure bottom heat exchanger flange. Re- move heat exchanger from furnace cabinet.

20 − Back wash heat exchanger with soapy water solution or steam. If steam is used it must be below 275°F (135°C) .

21 − Thoroughly rinse and drain the heat exchanger. Soap solutions can be corrosive. Take care to rinse entire assembly.

22 − Reinstall heat exchanger into cabinet making sure that the clamshells of the heat exchanger assembly are resting on the support located at the rear of the cabi- net. Remove the indoor blower to view this area through the blower opening.

23 − Re-secure the supporting screws along the vestibule sides and bottom to the cabinet.

24 − Reinstall cabinet screws on front flange at blower deck.

25 − Reinstall the primary limit on the vestibule panel.

26 − Route heating component wiring through hole in blow- er deck and reinsert strain relief bushing.

27 − Reinstall electrical junction box.

28 − Reinstall the combustion air inducer. Reconnect the 3−pin plug to the wire harness. Reconnect the two wires to the backup secondary limit, if applicable.

29 − Reinstall pressure switches and reconnect pressure switch wiring.

30 − Carefully connect combustion air pressure switch hosing from pressure switches to proper stubs on cold end header collector box.

31 − Reinstall condensate collars on each side of the fur- nace. Reconnect drain tubing to collector box.

32 − Reinstall condensate trap on same side as exhaust pipe. Reconnect condensate drain line to the conden- sate trap.

33 − Use securing screws to reinstall flue collars to either side of the furnace. Reconnect exhaust piping and ex- haust drain tubing.

34 − Replace flexible exhaust tee on combustion air induc- er and flue collars. Secure using three existing hose clamps.

35 − Reinstall burner box assembly in vestibule area.

36 − Reconnect flame roll−out switch wires.

37 − Reconnect sensor wire and reconnect 2−pin plug from ignitor.

38 − Secure burner box assembly to vestibule panel using four existing screws. Make sure burners line up in center of burner ports.

39 − Reinstall gas valve manifold assembly. Reconnect gas supply line to gas valve.

40 − Reinstall burner box cover.

41 − Reconnect wires to gas valve.

42 − Replace the blower compartment access panel.

43 − Refer to instruction on verifying gas and electrical con- nections when re−establishing supplies.

44 − Follow lighting instructions to light and operate fur- nace for 5 minutes to ensure that heat exchanger is clean and dry and that furnace is operating properly.

45 − Replace heating compartment access panel.

Cleaning the Burner Assembly

1 − Turn off electrical and gas power supplies to furnace. Remove upper and lower furnace access panels.

2 − Mark all gas valve wires and disconnect them from the valve.

3 − Disconnect the gas supply line from the gas valve. Re- move gas valve/manifold assembly.

4 − Mark and disconnect sensor wire from the sensor. Dis- connect 2-pin plug from the ignitor at the burner box.

5− Remove burner box cover and remove four screws which secure burner box assembly to vest panel. Re- move burner box from the unit.

NOTE − G61MP−135 units are secured to the vestibule panel by two additional screws. These screws must be removed for servicing; however it is not necessary to replace the screws.

6 − Use the soft brush attachment on a vacuum cleaner to gently clean the face of the burners. Visually inspect the inside of the burners and crossovers for any block- age caused by foreign matter. Remove any blockage.

7− Reconnect the sensor wire and reconnect the 2−pin plug to the ignitor wiring harness.

8 − Reinstall the burner box assembly using the existing four screws. Make sure that the burners line up in the center of the burner ports.

9 − Reinstall the gas valve manifold assembly. Reconnect the gas supply line to the gas valve. Reinstall the burn- er box cover.

10 − Reconnect the gas valve wires to the gas valve.

11 − Replace the blower compartment access panel.

12 − Refer to instruction on verifying gas and electrical con- nections when re−establishing supplies.

13 − Follow lighting instructions to light and operate fur- nace for 5 minutes to ensure that heat exchanger is clean and dry and that furnace is operating properly.

14 − Replace heating compartment access panel.

Page 54