Trane R Series, Installation Operation & Maintenance

Page: 143 / 188

RLC-SVX07A-EN 143
Refrigerant Charging
If the refrigerant charge needs to be adjusted, be certain to monitor the
subcooling and superheat measurements. The subcooling needs to be
between 6 F and 8 F when the unit is running fully loaded. The ambient
temperature is between 75 F and 100 F and the leaving water temperature is
between 40 F and 55 F. The superheat needs to be close to or at the
superheat setpoint entered in the UCM.
CAUTION:
Equipment Damage!
The evaporator water flow must be established and maintained
while adjusting the charge. Refrigerant pressures below 65 psig
can cause freezing and rupturing of the evaporator tubes.
Adding Refrigerant
The RTWA 70-125 ton units are shipped with an entire charge of refrigerant
and oil. The RTUA 70125 ton units are shipped with a holding charge of
nitrogen and the oil charge, excluding the additional oil charge needed for field
piping. If the unit has no pressure, the system must be leak tested prior to
adding refrigerant. Evacuate the system down to at least 100 microns prior to
adding the refrigerant.
CAUTION:
Equipment Damage!
Water must be flowing through the tube bundles during this
entire process. Refrigerant pressures below 65 psig can cause
freezing and rupturing of the heat exchangers.
1. Connect 115 VAC power to the master solenoid, the female load solenoid
and the male load/unload solenoids. This must be done to evacuate all of
the cavities in the compressor.
2. Open all service valves.
3. Connect hoses from the vacuum pump to the backseat ports on the suc-
tion line service valve and the discharge line service valve.
4. Evacuate the system to 100 microns and isolate the vacuum pump.
5. Confirm that no moisture or leaks are present by letting the vacuum stand
for several minutes.
6. Add refrigerant gas to the system through the backseat port on the dis-
charge service valve until the pressure is above 65 psig.
NOTE: Weigh in entire charge from Table 1 (RTWA only) and Paragraph
"Remote Air-Cooled Condenser Interconnecting Refrigerant Piping" on Page
45
(RTUA and RTCA units).
7. Once the pressure exceeds 65 psig, add liquid refrigerant through the 1/4
inch service valve between the EXV and the evaporator.
8. The unit may need to be started to add the entire charge. Once the unit is
started, monitor the subcooling and superheat to trim the charge.