Page 17
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 suction line temperature
TXV
FIXED
ORIFICE
APPROACH OR
SUBCOOLING
WEIGH-IN
SUPERHEAT
65ºF
(18.3ºC) and
Above
START: Determine how refrigerant is metered
39ºF
(3.8ºC) and
Below
Which indoor
metering
device?
WEIGH-IN
64ºF
(17.7ºC) and
Below
40ºF
(4.4ºC) and
Above
DETERMINING CHARGE METHOD
A
B
C
D
E
FIGURE 19
START: Measure outdoor ambient temperature
1.. Connect gauge set as illustrated in figure
17.
2.. Check Liquid and suction line pressures
3.. Compare unit pressures with table 6,
Normal Operating Pressures.
4.. Weigh in the unit nameplate charge plus
any charge required for line set
differences over feet.
Liquid Line
Set Diameter
Ounces per 5 feet (g per 1.5 m)
adjust from 15 feet (4.6 m) line set*
3/8" (9.5 mm)
3 ounce per 5’ (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.
Refrigerant
Charge per Line
Set Length
USE EITHER APPROACH
OR SUBCOOLING
METHOD
This nameplate is for illustration
purposes only. Go to actual
nameplate on outdoor unit for
charge information.
64ºF and
BELOW
65ºF
and
ABOVE
ABOVE or BE-
LOW
FIGURE 20
A
Once refrigerant charge is
correct, disconnect gauge set
and replace service port caps.
WEIGH IN TXV
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