Operating Principles
CVHH-SVX001A-EN 73
Purge Tank Subsystem
Any non-condensables that have accumulated from the
refrigerant vapor are left behind to collect in the purge
tank. As the quantity of non-condensables increases, the
heat transfer efficiency of the purge evaporator coil is
reduced, causing the purge compressor suction
temperature to decrease.
A float switch, mounted in the bottom of the purge tank,
indicates if there is excessive accumulation of liquid
refrigerant in the tank. A liquid level sensor, which resides
in the purge control panel, monitors the status of the float
switch.
If the normally closed float switch is open for more than
20 minutes, the purge controls will turn off the
refrigeration system and generate a non-latching
diagnostic—Purge Liquid Level Too High Warning. If the
float switch has re-closed after 20 minutes, the purge
controls will restart the refrigeration system.
If the float switch remains open for more than 20 minutes,
or if the float switch/liquid level restart cycle has occurred
Figure 40. Components of a Trane EarthWise purge system (back view)
1
1. Regeneration solenoid valve
2. Pressure-relief valve
3. Exhaust solenoid valve
4. Pump-out com pressor
5. Carbon tank heater
6. Automatic expansion valve
7. Pump-out solenoid valve
8. Pressure-relief device (fusible plug)
9. Carbon tank
10. Purge tank
11. Condensing unit
12. Chiller refrigerant supply line
9
5
3
4
7
10
11
6
8
2
1
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