Bryant 581A GAS Valve Adjustment, XI. Main Burners, XII. Filter Drier, XIII. Protective Devices

								BOTH CIRCUITS
				ALL OUTDOOR FANS MUST BE OPERATING
(DEG F)	140
VALVE	120
			ADD		CHARGE		IF ABOVE CURVE
LIQUIDAT	100
TEMPERATURELIQUID
	80
	60								REDUCE CHARGE IF BELOW CURVE
	40
		100				150	200			250	300	350	400
	50

LIQUID PRESSURE AT LIQUID VALVE (PSIG)

Fig. 35 — Cooling Charging Chart

X. GAS VALVE ADJUSTMENT

A. Natural Gas

The gas valve opens and closes in response to the thermostat or limit control.

When power is supplied to valve terminals D1 and C2, the main valve opens to its preset position.

The regular factory setting is stamped on the valve body (3.3 in. wg).

To adjust regulator:

1.Set thermostat at setting for no call for heat.

2.Turn main gas valve to OFF position.

3.Remove 1/8-in. pipe plug from manifold or gas valve pressure tap connection. Install a suitable pressure- measuring device.

4.Set main gas valve to ON position.

5.Set thermostat at setting to call for heat.

6.Remove screw cap covering regulator adjustment screw (See Fig. 36).

7.Turn adjustment screw clockwise to increase pres- sure or counterclockwise to decrease pressure.

8.Once desired pressure is established, set thermostat setting for no call for heat, turn off main gas valve, remove pressure-measuring device, and replace 1/8-in. pipe plug and screw cap.

XI. MAIN BURNERS

For all applications, main burners are factory set and should require no adjustment.

A.Main Burner Removal

1.Shut off (field-supplied) manual main gas valve.

2.Shut off power to unit.

3.Remove unit control box access panel, burner section access panel, and center post (Fig. 4 and 5).

4.Disconnect gas piping from gas valve inlet.

5.Remove wires from gas valve.

6.Remove wires from rollout switch.

7.Remove sensor wire and ignitor cable from IGC board.

8.Remove 2 screws securing manifold bracket to

basepan.

9.Remove 2 screws that hold the burner support plate flange to the vestibule plate.

10.Lift burner assembly out of unit.

B. Cleaning and Adjustment

1.Remove burner rack from unit as described in Main Burner Removal section above.

2.Inspect burners, and if dirty, remove burners from rack.

3.Using a soft brush, clean burners and crossover port as required.

4.Adjust spark gap. See Fig. 37.

5.Reinstall burners on rack.

6.Reinstall burner rack as described above.

XII. FILTER DRIER

Replace whenever refrigerant system is exposed to atmosphere.

XIII. PROTECTIVE DEVICES

A. Compressor Protection

Overcurrent

Each compressor has internal line break motor protection.

Overtemperature

Each compressor has an internal protector to protect it against excessively high discharge gas temperatures.

Crankcase Heater

The 581A units are equipped with a 70-watt crankcase heater to prevent absorption of liquid refrigerant by oil in the crankcase when the compressor is idle. The crankcase heater is energized whenever there is main power to the unit and the compressor is not energized.

IMPORTANT: After prolonged shutdown or servicing, ener- gize the crankcase heaters for 24 hours before starting the compressors.

Compressor Lockout

If any of the safeties (high-pressure, low-pressure, freeze protection thermostat, compressor internal thermostat) trip, or if there is loss of power to the compressors, the cooling lockout (CLO) will lock the compressors off. To reset, manu- ally move the thermostat setting.

B. Evaporator Fan Motor Protection

On size 155 units, an internal protector with auto-reset is included in the indoor fan motor as a protection against overcurrent.

On size 180 and 240 units, a manual reset, calibrated trip, magnetic circuit breaker protects against overcurrent. Do not bypass connections or increase the size of the breaker to correct trouble. Determine the cause and correct it before resetting the breaker.

Fig. 36 — Gas Valve

—29—