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 assembly 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 38.
| ML180UH BURNER, COMBUSTION AIR INDUCER ASSEMBLY & | |
| HEAT EXCHANGER REMOVAL |
|
| Gasket |
|
| Flue Transition |
|
| Pressure Switch |
|
Rollout Switches |
| |
(−090, −110 −135 units) |
| |
Rollout Switches | Ignitor | Heat Exchanger |
(−045 and −070 units) |
|
|
| Orifice Plate | Collector Box |
| Combustion Air Inducer |
|
Sensor |
|
|
|
| Retention Rings |
|
| Cross Over |
| Manifold And Gas Valve |
|
FIGURE 37
Page 36
