Carrier WEATHERMASTER 48/50Z030-105 - Manual (Page 131)

131
Gas System Adjustment (48Z Only)
GAS VALVE ADJUSTMENT — The gas valve opens and
closes in response to the unit 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. Switch 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. Switch 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. 50).
7. Turn adjustment screw clockwise to increase pressure
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.
MAIN BURNERS — For all applications, main burners are
factory set and should require no adjustment.
MAIN BURNER REMOVAL AND REPLACEMENT
1. Shut off (field-supplied) manual main gas valve.
2. Shut off power to unit.
3. Remove gas section access door, door frame, and corner
post.
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 form 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.
11. Replace burner assembly. Reinstall by reversing Steps 1
to 10.
Moisture/Liquid Indicator — A clear flow of liquid
refrigerant indicates sufficient charge in the system. Bubbles
indicate undercharged system or the presence of noncondens-
ables. Moisture in the system measured in parts per million
(ppm) changes the color of the indicator:
Green — moisture below 45 ppm (dry)
Chartreuse — 45 to 130 ppm (caution!)
Yellow — moisture above 130 ppm (wet)
Change filter driers at the first sign of moisture in the sys-
tem. See Carrier Charging Handbook for more information.
Filter Drier — Replace whenever the moisture/liquid indi-
cator shows moisture in the system.
Liquid Line Service Valve — Located immediately
ahead of the filter drier, this valve has a 1 /
4
-in. flare connection
for field charging. With the liquid circuit shut, the compressor
can be used to pump the refrigerant down into the high side.
The refrigerant can then be stored there by closing the com-
pressor discharge valve.
Compressor Discharge Service Valve — Each
compressor has one.
Compressor Suction Service Valve — Each com-
pressor has one.
Protective Devices
COMPRESSOR PROTECTION
Overcurrent — Each compressor has one manual reset,
calibrated trip, magnetic circuit breaker. Do not bypass connec-
tions or increase the size of the circuit breaker to correct trou-
ble. Determine the cause and correct it before resetting the
breaker.
Overtemperature — Each 06D compressor has an internal
protector to protect it against excessively high discharge gas
temperatures. Each 06E compressor has an external discharge
gas thermostat. See Fig. 51. They will reset, but the circuit will
automatically be locked out by the control board. Unit must be
manually reset by interrupting control power.
Crankcase Heater — Each compressor has a crankcase heater
to prevent absorption of liquid refrigerant by oil in the crank-
case when the compressor is idle. Since 115-v power for the
crankcase heaters is drawn from the unit control circuit, main
unit power must be on for the heaters to be energized.
Liquid Pressure at Liquid Valve (PSIG)
CHARGING CHART
BOTH CIRCUITS
ALL OUTDOOR FANS MUST BE OPERATING
Liquid T
emperature at Liquid V
alve (deg F)
140
120
100
80
60
40
50 100 150 200 250 300 350 400
Add Charge if Above Curve
Reduce Charge if Below Curve
Fig. 49 — Charging Chart — 48/50Z030-105 Units
IMPORTANT: Unit must be in operation at least
12 hours before moisture indicator can give an accurate
reading. With unit running, indicating element must be
in contact with liquid refrigerant to give a true reading.
INLET PRESSURE
TAP (ON SIDE)
1/8-IN. 27 NPT OUTLET PRESSURE
TAP (ON SIDE)
1/8-IN. 27 NPT
HIGH-FIRE REGULATOR
ADJUSTMENT SCREW LOW-FIRE REGULATOR
ADJUSTMENT SCREW
Fig. 50 — Gas Valve