Cleaning Burners; Cleaning Heat Exchangers; Primary Heat Exchangers - Bryant 355MAV Service And Maintenance Procedures Manual

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WARNING: Blower access panel door switch opens
115-v power to control center. No component operation
can occur. Caution must be taken when manually closing
this switch for service purposes. Failure to follow this
warning could result in personal injury or death.
15. If furnace is operating properly, release blower access panel
door switch, replace blower access panel, and replace main
furnace door.
III. CLEANING BURNERS
The following items should be performed by a qualified service
technician. If the burners develop an accumulation of light dirt or
dust, they may be cleaned by using the following procedure:
1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
3. Remove burner box cover.
4. Using backup wrench, disconnect gas supply pipe from gas
valve.
5. Remove wires from gas valve. Note location for reassem-
bly.
6. Remove burner box pressure tube from gas valve regulator
fitting.
7. Remove screws that secure manifold to burner box. (See
Fig. 5.)
MANIFOLD
MOUNTING
SCREW
Fig. 5—Burner Box Assembly
8. Remove manifold, orifices, and gas valve as 1 assembly.
9. Remove screws attaching burner assembly in burner box.
10. Remove burner assembly from burner box.
NOTE: All burners are attached to burner bracket and can be
removed as 1 assembly.
11. Clean burners with soft brush and vacuum.
12. Reinstall manifold, orifice, and gas valve assembly in
burner box. Ensure manifold seal grommet is installed
properly and burners fit over orifices.
13. Reconnect wires to gas valve. Refer to furnace wiring
diagram for proper wire location.
MANIFOLD
GAS VALVE
REGULATOR
FITTING
GAS VALVE
A93295
—4—
14. Reinstall burner box pressure tube to gas valve regulator
fitting.
15. Reinstall gas supply pipe to gas 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.
WARNING: Gas valve knob MUST be facing forward
or tilted upward. Failure to follow this warning could
result in property damage, personal injury, or death.
16. Replace burner box cover.
17. Replace main furnace door.
18. Turn on gas and electrical supplies to furnace.
IV. CLEANING HEAT EXCHANGERS
The following items should be performed by a qualified service
technician.
A. 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.
3. Disconnect wires or connectors to overtemperature switch,
gas valve, ignitor, 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 gas
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.
5.)
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. 6.)
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.