Page 10
Determining Charge Method
1.
WHEN TO CHARGE?
Warm weather best
Can charge in colder weather
CHARGE METHOD? Determine by:
Metering device type
Outdoor ambient temperature
REQUIREMENTS:
Sufficient heat load in structure
Indoor temperature between 70-80ºF
(21−26ºC)
Manifold gauge set connected to unit
Thermometers:
−
to measure outdoor ambient
temperature
−
to measure liquid line temperature
−
to measure vapor line temperature
TXV
RFC
APPROACH OR
SUBCOOLING
WEIGH-IN
SUPERHEAT
65ºF
(18.3ºC) and
Above
START: Determine how refrigerant is metered
39ºF
(3.8ºC) and
Below
Which
metering
device?
WEIGH-IN
64ºF
(17.7ºC) and
Below
40ºF
(4.4ºC) and
Above
FIGURE 12
Weigh in Charge
1.Recover the refrigerant from the unit.
2.Conduct leak check; evacuate as previously outlined.
3.Weigh in the unit nameplate charge plus any charge re-
quired for linesets differences from 15 feet. (If weighing
facilities are not available, use the subcooling method.)
TABLE 3
Refrigerant Charge per Line Set Lengths
Liquid Line Set
Diameter
Ounces per 5 feet (g per 1.5 m) adjust
from 15 feet (4.6 m) line set*
3/8 in. (9.5 mm)
3 ounce per 5 ft. (85 g per 1.5 m)
NOTE − *If line length is greater than 15 ft. (4.6 m), add this amount. If
line length is less than 15 ft. (4.6 m), subtract this amount.