Bryant 120 instruction manual Unit Damage Hazard, Cleaning Heat Exchanger

Page 50

312A

16. Reinstall control box assembly in furnace.

!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.

NOTE: Refer to Table 13 for motor speed lead relocation if leads were not identified before disconnection.

17.Reconnect blower leads to furnace control. Refer to furnace wiring diagram, and connect thermostat leads if previously disconnected.

18.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.

19.If furnace is operating properly, RELEASE BLOWER ACCESS DOOR SWITCH. Remove any jumpers or reconnect 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.

20.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.

21.Turn on gas supply and cycle furnace through one complete heating and cooling cycle. Verify the furnace temperature rise as shown in Adjustments Section. Adjust temperature rise as shown in Adjustments Section. If outdoor temperature is below 70_F, 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 disconnecting 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. 59 and 60 for correct igniter location.

9/32˝

5/16˝

A05025

Fig. 59 - Igniter Position-Side View

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

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Contents Ama CUT Hazard Safety ConsiderationsFurnace Reliability Hazard Width Bottom Flue Cabinet DimensionsIntroduction SizeInstallation Electrostatic Discharge ESD Precautions Procedure Codes and StandardsCarbon Monoxide Poisoning and Unit Damage Hazard LocationGeneral Property Damage Hazard FIRE, Injury or Death HazardFire Hazard Location Relative to Cooling EquipmentCarbon Monoxide Poisoning Hazard AIR for Combustion VentilationFurnace Corrosion Hazard Outdoor Combustion Air MethodAir for Combustion, Ventilation and Dilution for Outdoors Installation Upflow InstallationFIRE, EXPLOSION, and Carbon Monoxide Poisoning Hazard Downflow InstallationHorizontal Installation Suspended Furnace SupportFloor and Plenum Opening Dimensions Roll-Out ProtectionWidth Opening dimensionsFurnace Plenum Opening Floor Opening Casing Horizontal Unit Suspension General Requirements Filter Arrangement Carbon Monoxide Poisoning HazardAIR Ducts Ductwork Acoustical Treatment Supply Air ConnectionsAir Delivery CFM With Filter Speed External Static Pressure IN. WC Size Inlet2380 2285 2200 2085 1970 1835 Return Air Connections Air Delivery CFM With Filter*Downflow Furnaces GAS Piping Fire or Explosion HazardUpflow Return Air Configurations and Restrictions Maximum Capacity of Pipe Furnace Damage HazardElectrical Shock Hazard WiringElectrical Connections Electrical Shock and Fire Hazard Furnace MAY not Operate HazardElectrical Connection to J-BOX Electrical DataBOX Relocation Electrical Box on Furnace Casing Side. See Fig Power Cord Installation in Furnace J-BOXBX. Cable Installation in Furnace J-BOX Fire or Electrical Shock HazardTwo-Stage Furnace with Two-Speed Air Conditioner See notes 2, 11, and 12 on the page following these figures Accessories VentingGeneral Venting Requirements Masonry Chimney RequirementsChimney Inspection Chart Appliance Application Requirements Vent Height Internal Area of ChimneyUpflow Application-Vent Elbow Up Downflow Application-Vent Elbow Up Horizontal Right Application Vent Elbow Right Furnace Vent Orienta Orientation Tion PUTBTUH/HR Diameter Height FTRounded End of Knockout Burn HazardGeneral START-UP, ADJUSTMENT, and Safety CheckStart-Up Procedures Fire and Explosion HazardU.S AdjustmentsStage Furnace Setup Switch Description Altitude Derate Multiplier for U.S.ARedundant Automatic Gas Control Valve Seconds Size of Test Dial For Revolution Gas Rate cu ft/hrFurnace Overheating Hazard Speed Selection Color Speed AS ShippedDesired Heating Mode Setup Switch Blower OFF Delay SEC Check Safety ControlsStage Furnace Blower OFF delay Setup Switch Checklist BTUH/CU Altitude RangeSpecific Gravity of Natural GAS Gravity6001 to Specific Gravity of Natural GAS Altitude Range Heat Value Specific Gravity of Natural GAS Altitude RangeBTUH/CU FT FIRE, Personal Injury and Unit Damage Service and Maintenance ProceduresElectrical SHOCK, Fire or Explosion Hazard Specific Gravity of Natural GAS Heat Value AT AltitudeIntroduction Care and MaintenanceElectrical Controls and Wiring Electrical Shock Hazard Unit Operation Hazard Service Wiring Diagram Blower Motor and Wheel Electrical Shock Hazard Cleaning AND/OR Replacing AIR FilterFilter size information Furnace Filter Size CasingCleaning Heat Exchanger Unit Damage HazardSequence of Operation Igniter Position Top ViewTwo-Stage Heating Adaptive mode with Single-Stage Thermostat Single-Speed Cooling Single-Stage Thermostat and Two-Speed Cooling Adaptive ModeThermidistat Mode Continuous Blower Mode Wiring DiagramsTroubleshooting Troubleshooting Guide 2-Speed Blocked vent shutoff switch used in Chimney Adapter Kit Page Catalog No. II312A---45---8
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