Gas Pump Checkout
RTHC-SVD01B-EN 53
Section 10 Gas Pump Checkout
10-1. General
The falling film evaporator of the RTHC design is not a flooded evapo-
rator like RTHB. Residual oil 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 compres-
sor. 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 UCP2.
10-2. Gas Pump Checkout Procedure - Unit Off
To check the operation of the Gas Pump while the chiller is OFF, refer
to RTHC-SB-1B and do the following:
1. Turn off chiller.
2. Close (front seat) the ¼” angle valve (49) downstream of the
“cold” filter (48).
3. Back seat valve and Install gauge at (47). Re-open to read pres-
sure
4. Close the ¼" angle valve (11) on the condenser which supplies
the Gas Pump.
5. Make sure the gas pump solenoid valves (22 & 23) are de ener-
gized.
6. Pressurize the line between the Gas Pump and the ¼" angle
valve (47) upstream of the "cold" filter using POE oil taken from
the oil sump at (7). 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 (24), but may also indicate a
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