Trane 4TWR4 - Section 14. System Charge Adjustment; Charging Below 55°F Outdoor Using Weigh-In Method

18-BC95D1-5E-EN 15
STEP 7 - Stabilize the system.
1. Wait 20 minutes for the system condition to stabilize between adjustments.
Note: When the Liquid Line Temperature and Gage Pressure approximately match the chart, the system
is properly charged.
2. Remove gages.
3. Replace service port caps to prevent leaks. Tighten finger tight plus an additional 1/6 turn.
STEP 8 - Verify typical performance.
Refer to System Pressure Curves in the Service Facts to verify typical performance.
(Example only - see Service Facts)
PRESSURE CURVES FOR 4TWR3036B1000A
TAM4A0A36S31 TAM4A0A36S31
Cooling Heating
DISCHARGE PRESSURE (PSIG)
OUTDOOR TEMPERATURE (Degree F)
SUCTION PRESSURE (PSIG)
OUTDOOR TEMPERATURE (Degree F)
COOLING PERFORMANCE CAN BE CHECKED WHEN THE OUTDOOR TEMP IS ABOVE 65 DEG F.
TO CHECK COOLING PERFORMANCE, SELECT THE PROPER INDOOR CFM, ALLOW PRESSURES TO STABILIZE. MEASURE INDOOR WET BULB
TEMPERATURE, OUTDOOR TEMPERATURE, DISCHARGE AND SUCTION PRESSURES. ON THE PLOTS LOCATE OUTDOOR TEMPERATURE (1);
LOCATE INDOOR WET BULB (2); FIND INTERSECTION OF OD TEMP. & ID W.B. (3); READ DISCHARGE OR SUCTION PRESSURE IN LEFT
COLUMN (4) or (5).
EXAMPLE: (1) OUTDOOR TEMP. 82 F.
(2) INDOOR WET BULB 67 F.
(3) AT INTERSECTION ACTUAL:
(4) DISCHARGE PRESSURE IS 315 PSIG DISCHARGE PRESSURE SHOULD BE +/- 10 PSI OF CHART
(5) SUCTION PRESSURE IS 135 PSIG SUCTION PRESSURE SHOULD BE +/- 3 PSIG OF CHAR
T
INTERCONNECTING LINES
GAS - 3/4" O.D.
LIQUID - 3/8" O.D.
DWG.NO. 4TWR3036B1
(2)
(5) (3)
(1)
110
115
120
125
130
135
140
145
150
155
160
55 65 75 85 95 105 115
(2)
(4) (3)
(1)
200
250
300
350
400
450
500
55 65 75 85 95 105 115
INDOOR ENTERING WET BULB CURVES TOP TO BOTTOM 71,
67, 63 AND 59 DEG F.
INDOOR ENTERING W ET BULB CURVES TOP TO BOTTOM
71, 67, 63 AND 59 DEG F.
40
50
60
70
80
90
100
110
120
130
140
150
160
-5 5 15 25 35 45 55 65
250
300
350
400
450
500
-5 5 15 25 35 45 55 65
INDOOR ENTERING DRY BULB CURVES TOP TO BOTTOM 80, 70, AND 60
DEG F.
INDOOR ENTERING DRY BULB CURVESTOP TO BOTTOM 80, 70, AND
60 DEG F.
STEP 9 - Record System Information for reference.
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
Measured Suction Line Temp = __________ º F
Liquid Gage Pressure = __________ PSIG
Suction Gage Pressure = __________ PSIG
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.
14.3 Subcooling Charging Below 55º F Outdoor Temp. (In Heating Only)
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 associated with the additional length of tubing above 10 ft. and record it
below.
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.