Lennox ML195UH Installation Instructions Manual page 48

21 − Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger.
22 − Remove screws along vestibule sides and bottom
which secure vestibule panel and heat exchanger as-
sembly to cabinet. Remove two screws from blower
rails which secure bottom heat exchanger flange. Re-
move heat exchanger from furnace cabinet.
23 − Back wash heat exchanger with soapy water solution
or steam. If steam is used it must be below 275°F
(135°C) .
24 − Thoroughly rinse and drain the heat exchanger. Soap
solutions can be corrosive. Take care to rinse entire
assembly.
25 − Reinstall heat exchanger into cabinet making sure that
the rear baffle of the heat exchanger assembly is
nested under the support located at the rear of the
cabinet. Remove the indoor blower to view this area
through the blower opening.
26 − Re-secure the supporting screws along the vestibule
sides.
27 − Reinstall blower assembly and reinstall two screws
through rails.
28 − Reinstall cabinet screws on front flange at blower
deck.
29 − Reinstall screws securing top cap.
30 − Reinstall the primary limit on the vestibule panel.
31 − Route heating component wiring through hole in blow-
er deck and reinsert strain relief bushing.
32 − Reinstall pressure switch and reconnect pressure
switch wiring.
33 − Carefully connect combustion air pressure switch
hosing from pressure switch to proper stubs on cold
end header collector box.
34 − Reinstall 1/2" NPT (if removed) in the cold end header
box. Reconnect drain tubing to collector box.
35 − Reinstall condensate trap pipe. Reconnect conden-
sate drain line to the condensate trap.
36 − Reinstall electrical junction box.
37− Reinstall the combustion air inducer and flexible no
hub connector. Reconnect the 2−pin plug to the wire
harness.
39 − Reconnect drain tubes between flue collar and cold
end header box.
40 − Secure burner assembly to vestibule panel using four
existing screws. Burners are self aligning to center
of clam shells.
41 − Reconnect gas supply line to gas valve.
42 − Reconnect flame roll−out switch wires.
43 − Reconnect sensor wire and reconnect 2−pin plug from
ignitor.
44 − Reconnect wires to gas valve.
45 − Replace the blower compartment access panel.
46 − Refer to instruction on verifying gas and electrical con-
nections when re−establishing supplies.
47 − 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.
48 − Replace heating compartment access panel.
Cleaning the Burner Assembly
1 − Turn off gas and electrical power to the furnace. Re-
move heating compartment access panel.
2 − Disconnect the gas supply line from the gas valve.
3 − Disconnect and label wires from gas valve.
4 − Disconnect ignitor wiring at 2 circuit plug.
5 − Disconnect and label wires from rollout switch.
6 − Disconnect and label flame sensor wire.
7 − Disconnect and label ground wire from burner/man-
ifold assembly.
8 − Remove four screws that secures burner/manifold as-
sembly to vestibule. Remove the assembly and make
note not to allow ignitor plate to dislodge from the as-
sembly.
9 − Gently clean the face of the burners using the soft
brush attachment on a vacuum cleaner. Visually in-
spect the inside of the burners and crossovers for any
blockage caused by foreign matter. Remove any
blockage
10 − Reinstall the burner/manifold assembly using the ex-
isting four screws. Burners are self aligning to cen-
ter of clam shells.
11 − Reconnect ground wire.
12 − Reconnect flame sensor wire.
13 − Reconnect rollout switch wires.
14 − Reconnect ignitor wires.
15 − Reconnect gas valve wires.
16 − Reconnect gas supply line to gas valve.
17 − Refer to instructions on verifying gas and electrical
connections when re−establishing supplies.
18 − Follow instructions to place furnace in operation. Run
furnace 5 minutes to ensure burners are clean and op-
erating correctly.
19 − Replace heating compartment access panel.
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