Lennox iComfort SL280UH070V36A Manual page 49

A-Heat Exchanger and Burners
Cleaning the Heat Exchanger and Burners
NOTE - Use papers or protective covering in front of the fur­
nace during cleaning.
1 - Turn off both electrical and gas power supplies to fur­
nace.
2 - Remove flue pipe and top cap (some applications top
cap can remain) from the unit.
3 - Label the wires from gas valve, rollout switches, prima­
ry limit switch and make-up box then disconnect them.
4 - Remove the screws that secure the combustion air in­
ducer/pressure switch assembly to the collector box.
Carefully remove the combustion air inducer to avoid
damaging blower gasket. If gasket is damaged, it must
be replaced to prevent leakage.
5 - Remove the collector box located behind the combus­
tion air inducer. Be careful with the collector box gas­
ket. If the gasket is damaged, it must be replaced to
prevent leakage.
6 - Disconnect gas supply piping. Remove the screw se­
curing the burner box cover and remove cover. Re­
move the four screws securing the burner manifold as­
sembly to the vestibule panel and remove the assem­
bly from the unit.
7 - Remove screws securing burner box and remove
burner box.
8 - NOX units only - Remove screw securing NOX insert.
Remove NOX insert. See figure 23.
9 - Remove screws from both sides, top and bottom of
vestibule panel.
10- Remove heat exchanger. It may be necessary to
spread cabinet side to allow more room. If so, remove
five screws from the left side or right side of cabinet.
See figure 24.
11- Back wash using steam. Begin from the burner open­
ing on each clam. Steam must not exceed 275°F.
12- To clean burners, run a vacuum cleaner with a soft
brush attachment over the face of burners. Visually in­
spect inside the burners and crossovers for any block­
age caused by foreign matter. Remove any blockage.
Figure 22 shows burner detail.
13- To clean the combustion air inducer visually inspect
and using a wire brush clean where necessary. Use
compressed air to clean off debris and any rust.
14- Reinstall heat exchanger in vestibule. (Replace the
five screws in the cabinet from step 10 if removed).
15- NOX units only - replace NOX inserst.
16- Reinstall collector box and combustion air assembly.
Reinstall all screws to the collector box and combus­
tion air inducer. Failure to replace all screws may
cause leaks. Inspect gaskets for any damage and re­
place if necessary.
17- Reinstall burner box, manifold assembly and burner
box cover.
18- Reconnect all wires.
19- Reconnect top cap and vent pipe to combustion air in­
ducer outlet.
20- Reconnect gas supply piping.
21- Turn on power and gas supply to unit.
22- Set thermostat and check for proper operation.
23- Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means.
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.
24- If a leak is detected, shut gas and electricity off and re­
pair leak.
25- Repeat steps 24 and 26 until no leaks are detected.
26- Replace access panel.
Page 49
CAUTION