Payne PA1Z Installation, Start-Up And Service Instructions Manual page 12

B. Low Charge Cooling
Use Cooling Charging Charts, Fig. 15-20. Vary refrigerant
until the conditions of the appropriate chart are met. Note
that charging charts are different from the type normally used.
Charts are based on charging the units to the correct super-
heat for the various operating conditions. Accurate pressure
gage and temperature sensing device are required.
To measure suction pressure, perform the following:
1. Connect the pressure gage to the service port on the suc-
tion line.
2. Mount the temperature sensing device on the suction
line and insulate it so that outdoor ambient tempera-
ture does not affect the reading. Indoor-air cfm must be
within the normal operating range of the unit.
C. To Use Cooling Charging Charts
1. Take the outdoor ambient temperature and read the suc-
tion pressure gage.
2. Refer to appropriate chart to determine what the suc-
tion temperature should be.
3. If suction temperature is high, add refrigerant. If suc-
tion temperature is low, carefully recover some of the
charge.
4. Recheck the suction pressure as charge is adjusted.
EXAMPLE: (Fig. 15)
Outdoor Temperature . . . . . . . . . . . . . . . . . . . . . 85 F
Suction Pressure . . . . . . . . . . . . . . . . . . . . . . . 80 psig
Suction Temperature should be . . . . . . . . . . . . . 70 F
(Suction Temperature may vary ± 5° F.)
If Chargemaster charging device is used, temperature and
pressure readings must be accomplished using the charging
chart.
Fig. 15 — Cooling Charging Chart — PA1Z024
Fig. 16 — Cooling Charging Chart — PA1Z030
Fig. 17 — Cooling Charging Chart — PA1Z036
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