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16.3 CHARGING BY WEIGHT
For a new installation, evacuation of interconnecting tubing and indoor coil is
adequate; otherwise, evacuate the entire system. Use the factory charge shown in
“Electrical and Physical Data” on page 6 of these instructions or on the unit data
plate. Note that the charge value includes charge required for 15 ft. [4.6 m] of
standard-size inter-connecting liquid line without a filter drier. Calculate actual
charge required with installed liquid line size and length using:
1/4” [6.4 mm] O.D. = .3 oz./ft. [8.5 g/.30 m]
5/16” [7.9 mm] O.D. = .4 oz./ft. [11.3 g/.30 m]
3/8” [9.5 mm] O.D. = .6 oz./ft. [17.0 g/.30 m]
1/2” [12.7 mm] O.D. = 1.2 oz./ft. [34.0 g/.30 m]
Add 6 oz. for field-installed filter drier.
With an accurate scale (+/– 1 oz. [28.3 g]) or volumetric charging device, adjust
charge difference between that shown on the unit data plate and that calculated for
the new system installation. If the entire system has been evacuated, add the total
calculated charge.
IMPORTANT: Charging by weight is not always accurate since the application can
affect the optimum refrigerant charge. Charging by weight is considered a starting
point ONLY. Always check the charge by using the charging chart and adjust as
necessary. CHARGING BY LIQUID SUB-COOLING MUST BE USED FOR FINAL
CHARGE ADJUSTMENT.
With thermostat in the “Off” position, turn the power on to the furnace or air handler
and the heat pump. Start the heat pump and the furnace or air handler with the
thermostat. Verify that the outdoor unit is operating in second stage and the indoor
air mover is delivering the second-stage airflow for the system size.
16.4 GROSS CHARGING BY PRESSURES
Step 1. Following air flow verification and charge weigh in, run the unit for a
minimum of 15 minutes prior to noting pressures and temperature.
IMPORTANT: Indoor conditions as measured at the indoor coil must be within 2°F
of the following during gross charge (pressure) evaluation:
Cooling Mode: 80°F Dry Bulb
Step 2. Note the Outdoor Dry Bulb Temperature, ODDB°F = _______°F. Unit
charging is recommended under the following outdoor conditions ONLY:
Cooling Mode ONLY: 55°F outdoor dry bulb and above
!
NOTICE
ADJUST THE SYSTEM CHARGE BY WEIGHT FOR THE STRAIGHT
LENGTH OF THE REFRIGERANT LINE SET.
t
h
!
NOTICE
If the Indoor temperature is above or below this range, run the system to
bring the temperature down or run the electric heat/furnace to bring the
temperature within this range. System pressure values provided in the
Charge Chart for outdoor dry bulbs corresponding to conditions outside
of ranges listed below, are provided as reference ONLY.
