Bryant 312AAV/JAV Cleaning Heat Exchanger, Igniter Position-SideView, Unit Damage Hazard

312AAV

!CAUTION

UNIT DAMAGE HAZARD

Failure to follow this caution may result in shortened heat exchanger life.

Heating fan speed(s) MUST be adjusted to provide proper air temperature rise as specified on the rating plate. Recommended operation is at the midpoint of the rise range or slightly above. Refer to “SET TEMPERATURE RISE” under START-UP, ADJUSTMENT, and SAFETY CHECK.

14.Reinstall 2 screws securing blower assembly to blower deck.

15.Refer to furnace wiring diagram, and connect thermostat leads if previously disconnected.

16.To check blower for proper rotation:

a.Turn on electrical supply.

b.Manually close blower access door switch.

NOTE: If thermostat terminals are jumpered at the time blower access door switch is closed, blower will run for 90 sec before beginning a heating or cooling cycle.

c.Perform component self-test as shown at the bottom of the SERVICE label, located on the front of blower access door.

d.Verify blower is rotating in the correct direction.

17.If furnace is operating properly, RELEASE BLOWER ACCESS DOOR SWITCH. Remove any jumpers or re- connect any disconnected thermostat leads. Replace blower access door.

!WARNING

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal injury, or death.

Blower access door switch opens 115-v power to furnace control. No component operation can occur unless switch is closed. Exercise caution to avoid electrical shock from exposed electrical components when manually closing this switch for service purposes.

18.Downflow or horizontal furnaces with vent pipe through furnace only:

a.Install and connect short piece of vent pipe inside furnace to existing vent.

b.Connect vent connector to vent elbow.

19.Reinstall outer door.

20.Turn on gas supply and cycle furnace through one com- plete heating and cooling cycle. Verify the furnace temper- ature rise as shown in Adjustments Section. Adjust tem- perature rise as shown in Adjustments Section. If outdoor temperature is below 70_F (21_C) turn off circuit breaker to outdoor unit before running furnace in the cooling cycle. Turn outdoor circuit breaker on after completing cooling cycle.

CLEANING HEAT EXCHANGER

The following steps should be performed by a qualified service agency:

NOTE: If the heat exchangers get a heavy accumulation of soot and carbon, they should be replaced rather than trying to clean them thoroughly. 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, incorrect size or damaged manifold orifice(s), improper gas, or a restricted heat exchanger. Action must be taken to correct the problem.

If it becomes necessary to clean the heat exchangers because of dust or corrosion, proceed as follows:

1.Turn OFF gas and electrical power to furnace.

2.Remove outer access door.

3.Disconnect vent connector from furnace vent elbow.

4.For downflow or horizontal furnace having an internal vent pipe, remove internal vent pipe within the casing.

5.Disconnect wires to the following components. Mark wires to aid in reconnection of (be careful when discon- necting wires from switches because damage may occur):

a.Draft safeguard switch.

b.Inducer motor.

c.Pressure switches.

d.Limit overtemperature switch.

e.Gas valve.

f.Hot surface igniter.

g.Flame-sensing electrode

h.Flame rollout switches.

6.Remove screws that fasten the collector box assembly to the cell panel. Be careful not to damage the collector box. Inducer assembly and elbow need not be removed from collector box.

7.Disconnect gas line from gas manifold.

8.Remove the 5 screws that attach the burner assembly to the cell panel. The gas valve and individual burners need not be removed from support assembly. Remove NOx baffles if installed.

NOTE: Be very careful when removing burner assembly to avoid breaking igniter. See Fig. 53 and 54 for correct igniter location.

A05025

Fig. 53 - Igniter Position-Side View

9.Using field-provided 25-caliber rifle cleaning brush, 36-in. (914 mm) long 1/4-in. (6 mm) diameter steel spring cable, a variable speed, reversible electric drill, and vacuum cleaner, clean cells as follows:

a.Remove metal screw fitting from wire brush to allow in- sertion into cable.

b.Insert the twisted wire end of brush into end of spring cable, and crimp tight with crimping tool or crimp by

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