Page 29
Cleaning the heat exchanger requires a steel spring
snake," a reversible drill and a vacuum cleaner. The steel
spring snake may be constructed by purchasing a 4 ft. long
by 1/4 inch diameter steel wire cable and a 1/4 inch diame-
ter wire brush. These items are available at a hardware
store. Insert wire end of brush into the open end of the
spring cable. Crimp the cable around the brush so that the
brush is secured and will not come off during cleaning. At-
tach the other end of the cable to the reversible drill to com-
plete the tool for cleaning the heat exchanger.
1 − Turn off both electrical and gas power supplies to fur-
nace.
2 − Remove flue pipe and top cap from the unit. Label the
pressure switch wires, then disconnect them.
3 − Remove the four screws that secure the combustion air
inducer. Carefully remove the combustion air inducer to
avoid damaging blower gasket. If gasket is damaged, it
must be replaced to prevent leakage. See figure 31.
G40UH(X) BURNER & HEAT
EXCHANGER REMOVAL
FIGURE 31
HEAT EXCHANGER
BURNER BOX ASSEMBLY
4 − Remove the collector box located behind the combus-
tion air inducer. Be careful with the collector box gas-
ket. If the gasket is damaged you must replace it to pre-
vent leakage.
5 − Label the wires from gas valve and rollout switches,
then disconnect them.
6 − Disconnect gas supply piping. Remove four screws se-
curing the burner manifold assembly to the vestibule
panel and remove the assembly from the unit.
NOx INSERTS
(X models only)
FIGURE 32
NOx INSERTS
7 − NOx units only − remove the three screws that attach
the NOx insert to the corbel at the entrance to each
heat exchanger section. Carefully remove the NOx in-
sert from each section. See figure 32.
8 − Insert the brush end of cable snake into the top of one
of the heat exchanger openings. Do not force the
cable into the heat exchanger. Insert the cable and
operate the drill on slow speed. Move the cable in and
out of the heat exchanger section three or four times or
until sufficient cleaning is accomplished. Reverse drill
and slowly work the cable out of opening.
9− Repeat procedure for each heat exchanger section.
10− After each of the top heat exchanger sections has been
cleaned, insert the brush end of the cable snake into
the bottom openings of each of the heat exchanger
sections. Clean the bottom opening as described in
step 8.
11− Remove cable from heat exchanger. Use a vacuum
cleaner to remove debris knocked loose during clean-
ing from each heat exchanger section.
12− Attach the exhaust end (positive pressure) of the vacu-
um cleaner to the top of the heat exchanger section.
Any loose debris will be forced to the bottom of the heat
exchanger section. Vacuum debris from bottom open-
ings.
13− Replace collector box and combustion air inducer.
Check gaskets for damage. Damaged gaskets must be
replaced to avoid heat exchanger leaks. Replace all
screws to the collector box and combustion air inducer.
Failure to replace all screws may cause leaks.
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