Gas Valve Adjustment; Main Burners; Filter Drier; Replacement Parts - United Technologies Carrier Weathermaker 48A2 Controls, Start-Up, Operation, Service, And Troubleshooting

Gas Valve Adjustment

NATURAL GAS — The 2-stage gas valve opens and closes
in response to the thermostat or limit control.
When power is supplied to valve terminals 3 and 4, the pilot
valve opens to the preset position. When power is supplied to
terminals 1 and 2, the main valve opens to its preset position.
The regular factory setting is stamped on the valve body
(3.5 in. wg).
To adjust regulator:
1. Set thermostat at setting for no call for heat.
2. Switch main gas valve to OFF position.
3. Remove / -in. pipe plug from manifold. Install a water
1
8
manometer pressure-measuring device.
4. Switch main gas valve to ON position.
5. Set thermostat at setting to call for heat (high fire).
6. Remove screw cap covering regulator adjustment screw
(See Fig. 55).
7. Turn adjustment screw clockwise to increase pressure or
counterclockwise to decrease pressure.
8. Once desired pressure is established, set unit to no call for
heat (3.3-in. wg high fire).
9. Switch main gas valve to OFF position.
10. Remove pressure-measuring device and replace
pipe plug and screw cap.
11. Turn main gas valve to ON position and check heating
operation.
For all applications, main burners are
Main Burners —
factory set and should require no adjustment.
MAIN BURNER REMOVAL (Fig. 56)
1. Shut off (field-supplied) manual main gas valve.
2. Shut off power supply to unit.
3. Remove heating access panel.
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 4 screws that hold the burner support plate
flange to the vestibule plate.
10. Lift burner assembly out of unit.
11. Reverse procedure to re-install burners.
Filter Drier —
posed to atmosphere.
Replacement Parts —
parts may be obtained from any Carrier distributor upon request.
OUTLET PRESSURE
TAP (ON SIDE)
1/8-IN. 27 NPT
LOW-FIRE REGULATOR
ADJUSTMENT SCREW
1 / -in.
8
INLET PRESSURE
TAP (ON SIDE)
1/8-IN. 27 NPT
Fig. 55 — Gas Valve (Part Number EF33CW271)
141
Replace whenever refrigerant system is ex-
A complete list of replacement
HIGH-FIRE REGULATOR
ADJUSTMENT SCREW
ON/OFF SWITCH
A48-8364