Gas Valve Adjustment; Main Burners; Filter Drier; Replacement Parts - Carrier WeatherMaker 48A2020 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

Gas Valve Adjustment

NATURAL GAS
The 2-stage gas valve opens and closes in response to the ther-
mostat 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 ma-
1
8
nometer 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. 56).
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
plug and screw cap.
11. Turn main gas valve to ON position and check heating
operation.

Main Burners

For all applications, main burners are factory set and should re-
quire no adjustment.
MAIN BURNER REMOVAL (FIG. 57)
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

Replace whenever refrigerant system is exposed to atmosphere.

Replacement Parts

A complete list of replacement parts may be obtained from any
Carrier distributor upon request.
LOW-FIRE REGULATOR
1 / -in. pipe ADJUSTMENT SCREW
8
Fig. 56 — Gas Valve (Part Number EF33CW271)
Fig. 57 — Main Burner Removal
149
HIGH-FIRE REGULATOR
OUTLET PRESSURE
ADJUSTMENT SCREW
TAP (ON SIDE)
1/8-IN. 27 NPT
INLET PRESSURE
TAP (ON SIDE)
1/8-IN. 27 NPT
ON/OFF SWITCH