Lennox International Inc MERIT SERIES GAS FURNACE DOWNFLOW AIR DISCHARGE, ML193DF

Models: MERIT SERIES GAS FURNACE DOWNFLOW AIR DISCHARGE ML193DF

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19 − 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.

20 − Re-secure the supporting screws along the vestibule sides and bottom to the cabinet. Reinstall blower and mounting screws.

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

22 − Reinstall the primary limit on the vestibule panel.

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

24 − Reinstall electrical junction box.

25 − Reinstall the combustion air inducer. Reconnect the combustion air inducer to the wire harness.

26 − Reinstall pressure switches and reconnect pressure switch wiring.

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

28 − Reinstall condensate trap.

29 − Reconnect exhaust piping and exhaust drain tubing.

30 − Reinstall burner box assembly in vestibule area.

31 − Reconnect flame roll−out switch wires.

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

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

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

35 − Reconnect 2 wires to gas valve.

36 − Replace the blower compartment access panel.

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

38 − 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.

39 − 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 − Disconnect the 2−pin plug from the gas valve.

3 − Remove the burner box cover.

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

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

6− Remove four screws which secure burner box assem- bly to vest panel. Remove burner box from the unit.

7 − 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.

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

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

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

11 − Reconnect 2−pin plug to gas valve.

12 − Replace the blower compartment access panel.

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

14 − 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.

15 − Replace heating compartment access panel.

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Lennox International Inc MERIT SERIES GAS FURNACE DOWNFLOW AIR DISCHARGE, ML193DF 24 − Reinstall electrical junction box