Cleaning Heat Exchangers - Carrier 58MVB Service And Maintenance Instructions

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ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in electrical shock,
personal injury, or death.
Igniter wires must be securely placed in slot in manifold
grommet or else they could become pinched or severed and
electrically shorted.
16. Reconnect wires to gas valve and igniter. Refer to furnace
wiring diagram for proper wire location.
17. Reinstall burner box pressure tube to gas valve regulator
fitting.
18. Reinstall gas supply pipe to furnace gas control valve using
backup wrench on gas valve to prevent rotation and improper
orientation.
NOTE: Use propane gas resistant pipe dope to prevent gas leaks.
DO NOT use Teflon tape.
FIRE, EXPLOSION, UNIT DAMAGE HAZARD
Failure to follow this warning could result in property
damage, personal injury, or death.
Gas valve switch MUST be facing forward or tilted slightly.
19. Replace burner box cover.
20. Turn on gas and electrical supplies to furnace.
21. Check for gas leaks.
FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could result in
serious injury, death or property damage.
Never test for gas leaks with an open flame. Use a commer-
cially available soap solution made specifically for the
detection of leaks to check all connections.
22. Replace main furnace door.
Step 4—Cleaning Heat Exchangers
The following items should be performed by a qualified service
technician.
PRIMARY HEAT EXCHANGERS
If the heat exchangers get an accumulation of light dirt or dust on
the inside, they may be cleaned by the following procedure:
NOTE: If the heat exchangers get a heavy accumulation of soot
and carbon, both the primary and secondary heat exchangers
should be replaced rather than trying to clean them thoroughly due
to their intricate design. A build-up of soot and carbon indicates
that a problem exists which needs to be corrected, such as
improper adjustment of manifold pressure, insufficient or poor
quality combustion air, improper vent termination, incorrect size
or damaged manifold orifice(s), improper gas, or a restricted heat
exchanger (primary or secondary). Action must be taken to correct
the problem.
1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
PRIMARY HX
INLET OPENINGS
Fig. 8—Cleaning Inlet Openings of Primary Heat
UNIT DAMAGE HAZARD
Failure to follow this caution may result in furnace compo-
nent damage.
Label all wires prior to disconnection when servicing con-
trols. Wiring errors can cause improper and hazardous opera-
tion.
3. Disconnect wires or connectors to flame rollout switch, gas
valve, igniter, and flame sensor.
4. Disconnect combustion-air intake pipe from intake housing.
5. Remove the pressure switch tube from intake housing.
6. Remove screws attaching intake housing to burner box, and
rotate intake housing away from burner box for removal.
7. Using backup wrench, disconnect gas supply pipe from
furnace gas control valve.
8. Disconnect pressure tubing from gas valve.
9. Remove 2 screws attaching top filler panel and rotate upwards
to gain access to screws attaching burner box to cell panel.
10. Remove screws attaching burner box to cell panel. (See Fig.
6.)
NOTE: Burner box, cover, manifold, gas valve, and burner
assembly should be removed as 1 assembly.
11. Clean heat exchanger openings with a vacuum and a soft
brush. (See Fig. 8.)
NOTE: After cleaning, inspect the heat exchangers to ensure they
are free of all foreign objects that may restrict flow of combustion
products.
12. Reverse items 4 through 10 for reassembly.
UNIT MAY NOT OPERATE
Failure to attach ground wire to an adequate casing ground
may cause the furnace control to lock out.
The ground wire from the gas valve MUST be attached to the
burner box attachment screw.
NOTE: Be sure burner box gasket is installed between burner box
and cell panel. (See Fig. 6.) If gasket is damaged, replace it.
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Exchangers
A96305