Page 44
A-Heat Exchanger and Burners
Cleaning the Heat Exchanger and Burners
Figure 26 (-01 through -04 models) and Figure 27 (-05
and later models.)
NOTE - Use papers or protective covering in front of the
furnace during cleaning.
1 - Turn o both electrical and gas power supplies to
furnace.
2 - -05 models and later - remove the air intake
assembly from outside the cabinet. The assembly
is not secured with screws or glue and will remove
with ease. See Figure 28.
3 - Remove ue pipe and top cap (some applications
top cap can remain) from the unit.
4 - Label the wires from gas valve, thermal switch,
primary limit switch and make-up box then
disconnect them.
5 - Remove the screws that secure the combustion air
inducer to the collector box.
6 - Disconnect gas supply piping. Remove the screw
securing the air fuel plenum and remove along with
the air intake assembly as one component.
7 - Remove screws from both sides, top and bottom of
vestibule panel.
8 - Remove heat exchanger. It may be necessary
to spread cabinet side to allow more room. If so,
remove ve screws from the left side or right side of
cabinet. See Figure 28.
9 - Back wash using steam. Begin from the burner
opening on each tube. Steam must not exceed
275°F.
10 - To clean burner, remove from the air gas plenum
and run a vacuum cleaner over the face of burner.
Visually inspect inside the burner for any blockage
caused by foreign matter. Remove any blockage.
Figure 29 shows burner detail. Replace gasket
between burner plate and air fuel plenum then
re-install burner plate.
11 - To clean the combustion air inducer visually inspect
and using a wire brush clean where necessary. Use
compressed air to clean o debris and any rust.
Screen
2” PVC Pipe 2 ½”
Length
Elbow
Reducer
Air Intake Pipe Connections Upflow
-05 and later models
Note - Assembly may be rotated
to accommodate installation
4 ½”
FIGURE 29
12 - Reinstall heat exchanger in vestibule. (Replace the
ve screws in the cabinet from step 10 if removed).
13 - Reinstall the air fuel plenum and air intake assembly.
Re-install the combustion air inducer assembly.
Make note to re-install all screws. Failure to replace
all screws may cause leaks.
14 - Reconnect all wires.
15 - Reconnect top cap and vent pipe to combustion air
inducer outlet.
16 - Reconnect gas supply piping.
17 - -05 models and later, using a rubber mallet
reconnect the air intake assembly removed from
the outside of the cabinet in step 2.
18 - Turn on power and gas supply to unit.
19 - Set thermostat and check for proper operation.
20 - Check all piping connections, factory and eld, for
gas leaks. Use a leak detecting solution or other
preferred means.
CAUTION
Some soaps used for leak detection are corrosive
to certain metals. Carefully rinse piping thoroughly
after leak test has been completed. Do not use
matches, candles, ame or other sources of ignition
to check for gas leaks.
21 - If a leak is detected, shut gas and electricity o and
repair leak.
22 - Repeat steps 17 and 18 until no leaks are detected.
23 - Replace access panel.
Remove 5 screws if necessary
(cabinet for reference only)
1
2
3
4
5
FIGURE 30
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