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Cleaning Heat Exchanger
IMPORTANT
Safety glasses and surgical mask should be worn
when cleaning heat exchanger and or burner
assembly.
If cleaning the heat exchanger becomes necessary, follow
the below procedures and refer to figure 1 when disassem-
bling unit. Use papers or protective covering in front of fur-
nace while removing heat exchanger assembly.
1 − Turn off electrical and gas supplies to the furnace.
2 − Remove the upper and lower furnace access panels.
3 − Mark all gas valve wires and disconnect them from
valve.
4 − Remove gas supply line connected to gas valve. Re-
move gas valve/manifold assembly.
5 − Remove sensor wire from sensor. Disconnect 2-pin
plug from the ignitor.
6 − Disconnect wires from flame roll−out switch.
7 − Remove burner box front cover and remove burner box
screws at the vestibule panel. Set burner box assembly
aside.
NOTE − If necessary, clean burners at this time. Follow
procedures outlined in Burner Cleaning section.
8 − Loosen three clamps and remove flexible exhaust tee.
9 − Remove 3/8 inch rubber cap from condensate drain
plug and drain. Replace cap after draining.
10 − Disconnect condensate drain line from the condensate
trap. Remove condensate trap (it may be necessary to
cut drain pipe). Remove screws that secure both con-
densate collars to either side of the furnace and re-
move collars. Remove drain tubes from cold end head-
er collector box.
11 − Disconnect condensate drain tubing from flue collar.
Remove screws that secure both flue collars into place.
Remove flue collars. It may be necessary to cut the ex-
iting exhaust pipe for removal of the fittings.
12 − Disconnect the 2-pin plug from the combustion air in-
ducer. Disconnect the two wires to the secondary limit,
if applicable. Remove four screws which secure com-
bustion air inducer to collector box Remove combus-
tion air inducer assembly. Remove ground wire from
vest panel.
13 − Mark and disconnect combustion air pressure tubing
from cold end header collector box.
14 − Mark and remove wires from pressure switch. Remove
pressure switch. Keep tubing attached to pressure
switch.
15 − Remove electrical junction box from the side of the fur-
nace.
16 − 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.
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. Remove
heat exchanger from furnace cabinet. Do not remove
turbulators or baffles from secondary heat ex-
changer.
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 as-
sembly.
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 cabinet.
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 pressure swtich and reconnect pressure
switch wiring.
28 − Carefully connect combustion air prove switch hos-
ing from prove switches to proper stubs on cold end
header box.
29 − Reinstall condensate collars on each side of the fur-
nace. Reconnect drain tubing to collector box.
30 − Reinstall condensate trap on same side as exhaust
pipe. Reconnect condensate drain line to the conden-
sate trap.
31 − Reinstall electrical junction box.
32 − Reinstall the combustion air inducer. Reconnect the
2−pin plug to the wire harness. Reconnect the two wires
to the secondary limit, if applicable.
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 inducer
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.
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