Lennox ELITE Series Installation Instructions Manual page 48

21 − 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.
22 − Back wash heat exchanger with soapy water solution
or steam. If steam is used it must be below 275°F
(135°C) .
23 − Thoroughly rinse and drain the heat exchanger. Soap
solutions can be corrosive. Take care to rinse entire
assembly.
24 − Reinstall heat exchanger into cabinet making sure that
the clamshells of the heat exchanger assembly is en-
gaged properly into the support bracket on the blower
deck. Remove the indoor blower to view this area
through the blower opening.
25 − Re-secure the supporting screws along the vestibule
sides and bottom to the cabinet.
26 − Reinstall cabinet screws on front flange at blower
deck.
27 − Reinstall the primary limit on the vestibule panel.
28 − Route heating component wiring through hole in blow-
er deck and reinsert strain relief bushing.
29 − Reinstall electrical junction box.
30 − Reinstall the cold end header box.
31 − Reinstall the combustion air inducer. Reconnect the
plug to the wire harness.
32 − Reinstall pressure switches and reconnect pressure
switch wiring.
33 − Carefully connect combustion air pressure switch
tubing from pressure switches to proper ports on
cold end header collector box.
34 − Reconnect condensate drain line to the cold end
header box.
35 − Use securing screws to reinstall flue collar to the top
cap on the furnace. Reconnect exhaust piping and ex-
haust drain tubing.
36 − Replace flexible exhaust adapter on combustion air in-
ducer and flue collar. Secure using two existing hose
clamps.
37 − Reinstall burner box assembly in vestibule area. Se-
cure burner box assembly to vestibule panel using
four existing screws. Make sure burners line up in
center of burner ports
38 − Reconnect flame roll−out switch wires.
39 − Reconnect sensor wire and reconnect 2−pin plug from
ignitor.
40 − Reinstall gas valve manifold assembly. Reconnect
gas supply line to gas valve.
41 − Reconnect the combustion air intake pipe.
42 − Reinstall burner box cover.
43 − Reconnect wires to gas valve.
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44 − Replace the blower compartment access panel.
45 − Reconnect gas supply piping. Turn on power and gas
supply to unit.
46− Follow lighting instructions on unit nameplate to light
and operate furnace for 5 minutes to ensure the fur-
nace is operating properly.
47− Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means.
48− Replace heating compartment access panel.
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly af-
ter leak test has been completed. Do not use
matches, candles, flame or other sources of ignition
to check for gas leaks.
Cleaning the Burner Assembly (if needed)
1 − Turn off electrical and gas power supplies to furnace.
Remove upper and lower furnace access panels.
2 − Disconnect the wires from the gas valve.
3 − Remove the burner box cover (if equipped).
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 wires from flame rollout switches.
6 − Disconnect combustion air intake pipe. It may be nec-
essary to cut the existing pipe to remove burner box
assembly.
7 − Remove four screws which secure burner box assem-
bly to vest panel. Remove burner box from the unit.
8 − 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.
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 − Reconnect the sensor wire and reconnect the 2−pin
plug to the ignitor wiring harness. Reconnect wires to
flame rollout switches.
11 − Reinstall the gas valve manifold assembly. Reconnect
the gas supply line to the gas valve. Reinstall the burn-
er box cover.
12 − Reconnect wires to gas valve.
13 − Replace the blower compartment access panel.
14 − Refer to instruction on verifying gas and electrical con-
nections when re−establishing supplies.
15 − 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.
16 − Replace heating compartment access panel.
Page 48
CAUTION