Lennox EL195UHE Unit Information page 48

12 − Mark and disconnect all combustion air pressure tub-
ing from cold end header collector box.
13 − Mark and remove wires from pressure switch assemb-
ly. Remove the assembly. Keep tubing attached to
pressure switches.
14 − Disconnect the plug from the combustion air inducer.
Remove two screws which secure combustion air in-
ducer to collector box. Remove combustion air induc-
er assembly. Remove ground wire from vest panel.
15 − Disconnect the condensate drain line.
16 − Remove cold end header box.
17 − Remove electrical junction box from the side of the fur-
nace.
18 − Mark and disconnect any remaining wiring to heating
compartment components. Disengage strain relief
bushing and pull wiring and bushing through the hole in
the blower deck.
19 − Remove the primary limit from the vestibule panel.
20 − Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger.
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.
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.
Page 48
CAUTION