Bryant Preferred Series Service And Maintenance Instructions page 17

LOW-CHARGE COOLING
Using Cooling Charging Charts (Fig. 21-24), vary refrigerant until
the conditions of the appropriate chart are met. Note the charging
charts are different from the type normally used. Charts are based
on charging the units to the correct superheat for the various oper-
ating conditions. Accurate pressure gage and temperature sensing
devices are required. Connect the pressure gage to the service port
on the suction line. Mount the temperature sensing device on the
suction line and insulate it so that outdoor ambient temperature
does not affect the reading. Indoor-air cfm must be within the nor-
mal operating range of the unit.
581J SIZE DESIGNATION
17
20
24
28
EXAMPLE:
Model 581J*28
Circuit A
Outdoor Temperature . . . . . . . . . . . . . . . . . . . . . . . . . 85°F (29°C)
Suction Pressure . . . . . . . . . . . . . . . . . . . . . . . . 125 psig (862 kPa)
Suction Temperature should be . . . . . . . . . . . . . . . . . 63°F (17°C)
NOMINAL TON
REFERENCE
15
17.5
20
25
17
Circuit B
Outdoor Temperature . . . . . . . . . . . . . . . . . . . . . . . . . .85°F (29°C)
Suction Pressure . . . . . . . . . . . . . . . . . . . . . . . . 120 psig (827 kPa)
Suction Temperature should be . . . . . . . . . . . . . . . . . .58°F (14°C)
USING THE COOLING CHARGING CHARTS
Take the outdoor ambient temperature and read the suction pres-
sure gage. Refer to chart to determine what suction temperature
should be. If suction temperature is high, add refrigerant.
If suction temperature is low, carefully recover some of the charge.
Recheck the suction pressure as charge is adjusted.
Select the appropriate unit charging chart from Fig. 21-24.
Take the outdoor ambient temperature and read the suction pres-
sure gage. Refer to chart to determine what suction temperature
should be. If suction temperature is high, add refrigerant. If suc-
tion temperature is low, carefully recover some of the charge. Re-
check the suction pressure as charge is adjusted.
For sizes 17-28, perform this procedure once for Circuit A and
once for Circuit B.