Two- Stage Multi Position Furnace
Service Manual
38
440 08 2002 02
28. HEAT EXCHANGER REMOVAL/REPLACEMENT
“Exploded” Parts View -- Typical Four Position Furnaces
Figure 48
25--23--43a
Secondary Heat Exchanger
1. Turn ”OFF” electrical power and gas supply to furnace.
2. Disconnect vent pipe to furnace at flexible coupling.
3. Remove combustion blower.
4. Remove machine screws securing transition drain trap
assembly to furnace front partition.
5. Remove the collector box.
6. Loosen the four(4) screws on the manifold or as an alter-
native the four(4) screws on the manifold bracket.
7. Move the manifold bracket and valve up enough so the
secondary heat exchanger will clear the flange on the
baffle.
8. Remove machine screws securing secondary heat ex-
changer inlet flange to lower partition.
9. Remove screws around perimeter of lower partition.
10. Removed screws securing secondary heat exchanger
to the supports.
11. Coil can now be removed from furnace.
12. Reverse procedure to reinstall, making sure that any
gaskets that have been torn during disassembly are
replaced with new ones.
Primary Heat Exchanger
1. Turn ”OFF” electrical power and gas supply to furnace.
2. Disconnect vent pipe to furnace at flexible coupling.
3. Disconnect combustion air inlet pipe at top panel if
needed.
4. Remove furnace top panel.
5. Disconnect gas piping to furnace at gas valve. Note: Be-
fore performing next step, insure that the wiring dia-
gram is available and readable, or tag all wires first.
6. Disconnect tubing and wiring to pressure switch, limit
switches, and gas valve.
7. Remove screws securing burner box to front partition.
8. Remove combustion blower.
9. Remove machine screws securing transition assembly
to furnace partition.
10. Remove the collector box.
11. Remove machine screws securing secondary heat ex-
changer inlet flange to lower partition.
12. Remove screws around perimeter of both the upper
and lower partitions (leaving the screws across the
center of the two panels in place).
13. Primary Heat Exchanger can now be removed with
both upper and lower partitions attached.
14. Reverse procedure to reinstall, making sure that any
gaskets that have been torn during disassembly are
replaced with new ones.
15. After reassembly, turn the gas supply on, and check for
leaks. All leaks must be repaired immediately.
16. Perform an operational check of the furnace.