141
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
1
/
8
-in. pipe plug from manifold. Install a water
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
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
1
/
8
-in.
pipe 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 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 —
Replace whenever refrigerant system is ex-
posed to atmosphere.
Replacement Parts —
A complete list of replacement
parts may be obtained from any Carrier distributor upon request.
INLET PRE
SS
URE
TAP (ON
S
IDE)
1/
8
-IN. 27 NPT
OUTLET PRE
SS
URE
TAP (ON
S
IDE)
1/
8
-IN. 27 NPT
HIGH-FIRE REGULATOR
ADJU
S
TMENT
S
CREW
LOW-FIRE REGULATOR
ADJU
S
TMENT
S
CREW
ON/OFF
S
WITCH
Fig. 55 — Gas Valve (Part Number EF33CW271)
A48-8364
Summary of Contents for Carrier Weathermaker 48A2
Page 105: ...105 Fig 20 Typical Main Control Box Wiring Schematic 48 50A2 A3 A4 A5 Units...
Page 106: ...106 Fig 21 Typical Auxiliary Control Box Wiring Schematic...
Page 107: ...107 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown a48 8357...
Page 108: ...108 TO NEXT PAGE Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown A48 7296...
Page 109: ...109 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont A48 8358...
Page 110: ...110 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown a50 8228...
Page 111: ...111 Fig 25 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown...
Page 112: ...112 Fig 26 Typical Low Ambient Controls Option Wiring...
Page 113: ...113 Fig 27 Typical Small Chassis Component Location Size 020 035 Units...
Page 114: ...114 Fig 28 Typical Large Chassis Component Locations Size 040 060 Units...
Page 118: ...118 Fig 30 Economizer Control Board ECB1 and VAV Control Board ECB2 A48 7706...
Page 142: ...142 A48 3733 Fig 56 Main Burner Removal...
Page 176: ...176 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716...
