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506374−01 03/10
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
RFC
APPROACH OR
SUBCOOLING
WEIGH-INSUPERHEAT
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 11. Determining Charge Method
WEIGH IN TXV
START: Measure outdoor ambient temperature
1. Check Liquid and suction line pressures
2. Compare unit pressures with Table 3,
Normal Operating Pressures.
3. Conduct leak check; evacuate as
previously outlined.
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.
ABOVE or
BELOW
65ºF
(18.3ºC) and
Above
64ºF
(17.7ºC) and
Below
Figure 12. HFC−410A Weigh In TXV Method
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