RTHD and RTAC - Trane

Gas Pump - RTHD Only
Residual oil in a falling film evaporator will not immediately be recovered by the
oil separators and will eventually log in the evaporator. Oil cannot be returned as
oil/liquid droplets pulled up the suction line of the compressor. The oil is instead
returned by alternatively filling and draining a small tank with refrigerant from
the bottom of the evaporator. The fill cycle is controlled by energizing the fill
solenoid valve which vents the tank back to the evaporator, allowing a gravity
feed of liquid through a check valve into the tank. This refrigerant which has
anywhere from 3% to 8% oil, is then drained by energizing the drain valve which
applies condenser pressure to the tank thus “pushing” the liquid up a line which
drains directly to the suction of the compressor. The check valve prevents the
liquid or high pressure gas from re-entering the evaporator. The solenoid valves
are controlled directly by the CH530.
Gas Pump Checkout Procedure - Unit Off
To check the operation of the Gas Pump while the chiller is OFF do the following:
1 Turn off chiller.
2 Close (front seat) the ¼” angle valve downstream of the “cold” filter.
3 Back seat valve and Install gauge. Re-open to read pressure
4 Close the ¼" angle valve on the condenser which supplies the Gas Pump.
5 Make sure the gas pump solenoid valves are de energized.
6 Pressurize the line between the Gas Pump and the ¼" angle valve upstream of
the "cold" filter using POE oil taken from the oil sump. If desired, refrigerant
from the condenser can be used as well.
7 Pressurize the line to approximately 115 psi.
8 Monitor the pressure leak rate in the line. It's typical to see an immediate 5 psi
drop in pressure, and then a slow drop thereafter. A normal leak rate is 10 psi
in 5 minutes. A rapidly falling pressure may indicate a leaking check valve, but
may also indicate a leaking solenoid valve. Further testing may be necessary
to determine which component is leaking.
9 Before returning to service, make sure all valves and coils are returned to their
normal positions.
RLC-SVD05A-EN 59