Bryant 120 Start-Up,Adjustment, And Safety Check, General, Start-UpProcedures, 312A, Fire Hazard

In Canada: Per section 8.24.2 of the CAN/CSA-B149.1-05, any listed mechanical venter may be used, when approved by the authority having jurisdiction.

Select the listed mechanical venter to match the Btuh input of the furnace being vented. Follow all manufacturer￿s installation requirements for venting and termination included with the listed mechanical venter.

START-UP, ADJUSTMENT, AND SAFETY

CHECK

Step 1 — General

!WARNING

FIRE HAZARD

Failure to follow this warning could result in personal injury, death and/or property damage.

This furnace is equipped with manual reset limit switches in the gas control area. The switches open and shut off power to the gas valve if a flame roll-out or overheating condition occurs in the gas control area. DO NOT bypass the switches. Correct problem before resetting the switches.

1.Maintain 115-v wiring and ground. Improper polarity will result in rapid flashing LED and no furnace operation.

2.Make thermostat wire connections at the 24-v terminal block on the furnace control. Failure to make proper connections will result in improper operation. (See Fig. 24.)

3.Gas supply pressure to the furnace must be greater than 4.5-in. wc (0.16 psig ) but not exceed 14-in. wc (0.5 psig).

!CAUTION

CUT HAZARD

Failure to follow this caution may result in personal injury.

Sheet metal parts may have sharp edges or burrs. Use care and wear appropriate protective clothing, safety glasses and gloves when handling parts and servicing furnaces.

4.Check all manual-reset switches for continuity.

5.Install blower compartment door. Door must be in place to operate furnace.

6.Setup switch descriptions The 2 stage furnace has DIP switches used to select thermostat staging and blower off delay timings. For switch locations on Furnace control board, See Fig. 34 and 58.

7.Setup switch descriptions - See Table 10.

Step 2 — Start-Up Procedures

!WARNING

FIRE AND EXPLOSION HAZARD

Failure to follow this warning could cause personal injury, death and/or property damage.

Never purge a gas line into a combustion chamber. Never use matches, candles, flame, or other sources of ignition for the purpose of checking leakage. Use a soap-and-water solution to check for leakage.

1.Purge gas lines after all connections have been made.

2.Check gas lines for leaks.

!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 control. No component operation can occur unless switch is closed. Caution must be taken when manually closing this switch for service purposes.

3.To Begin Component Self-Test:

Remove blower access door. Disconnect the thermostat R lead from furnace control board. Manually close blower door switch. Short (jumper) the COM-24v terminal on control to the TEST/TWIN 3/16-inch quick-connect terminal on control until the LED goes out (approximately 2 sec). Gas valve and humidifier will not be turned on. Remove jumper from terminals. (See Fig. 34 and Table 10.)

NOTE: The furnace control allows all components, except the gas valve, to be run for short period of time. This feature helps diagnose a system problem in case of a component failure. Component test feature will not operate if any thermostat signal is present at the control.

Refer to service label attached to furnace or See Fig. 57. Component test sequence is as follows:

a.LED will display previous status code 4 times.

b.Inducer motor starts on high-speed and continues to run until Step g of component test sequence.

c.Hot surface igniter is energized for 15 sec., then off.

d.Blower motor operates on LO-HEAT speed for 10 sec.

e.Blower motor operates on HI-HEAT speed for 10 sec.

f.Blower motor operates on COOL speed for 10 sec.

g.Inducer motor goes to low-speed for 10 sec., then stops.

h.Reconnect R lead to furnace control board, remove tape from blower door switch and re-install blower door.

4.Operate furnace per instruction on inner door.

5.Verify furnace shut down by lowering thermostat setting below room temperature.

6.Verify furnace restarts by raising thermostat setting above room temperature.

312A

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