Trane 4TWX8 Installer's Manual page 21

STEP 9 - Record System Information for refer-
ence.
Record system pressures and temperatures
after charging is complete.
Outdoor model number = _________________
Measured Outdoor Ambient = __________ º F
Measured Indoor Ambient = __________ º F
Measured Liquid Line Temp = __________ º F
14.3 Subcooling Charging Below 55º F Outdoor Temp. (In Heating Only)
The Subcooling Charging method in cooling is not recommended below 55º F outdoor temperature.
The only recommended method of charging at outdoor temperatures below 55º F is weighing in the charge in
heating mode and referencing the refrigerant pressure curves for typical performance.
STEP 1 - Determine additional charge.
Note: The nameplate charge value represents
the amount of refrigerant shipped in the outdoor
unit and is compatible with 10 feet of AHRI rated
refrigerant lines and the smallest AHRI rated
coil.
Using the method below, find the charge associ-
ated with the additional length of tubing above
10 ft. and record it below.
Calculating Charge Using the Weigh-In Method
1) Measure in feet the distance between the
outdoor unit and the indoor unit. (Include
the entire length of the line from the service
valve to the IDU.) Subtract 10 ft from this
entire length and record on line 1.
2) Enter the charge multiplier (0.6 oz/ft). Each
linear foot of interconnecting tubing requires
the addition of 0.6 oz of refrigerant.
3) Multiply the total length of refrigerant tubing
(Line 1) times the value on Step 2. Record
the result on Line 3 of the Worksheet.
4) This is the amount of refrigerant to weigh-in
prior to opening the service valves.
18-BC91D1-6B-EN
Measured Suction Line Temp = __________ º F
Liquid Gage Pressure = __________ PSIG
Suction Gage Pressure = __________ PSIG
Weigh-In Method can be used for the initial
installation, or anytime a system charge is being
replaced. Weigh-In Method can also be used
when power is not available to the equipment
site or operating conditions (indoor/outdoor
temperatures) are not in range to verify with the
subcooling charging method.
1. Total Line length (ft) –10 ft ______________
2. Charge multiplier
3. Step 1 x Step 2
4. Refrigerant (oz)
x ___0.6 oz _____
= _____________
= _____________
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