Tranquility
®
Digital (DXM2)—Troubleshooting Guide
Rev.: 10 March, 2015
26
Geothermal Heating and Cooling
Expansion Valve System
• Feeds refrigerant based upon the measured superheat at the compressor suction. It will appropriately “meter” to maintain
superheat setting.
• Able to handle a wide range of capacities (inlet water temperatures)
• Bullet proof - You can’t ood a compressor by overcharging with an expansion valve in the system and thus run the risk of
compressor failure.
• Stores excess refrigerant in condenser
Overcharged System
• High subcooling
• Superheat will be maintained by expansion valve at valve setting
• Basically no change in capacity
• High discharge pressure
Undercharged System
• Low subcooling
• High superheat
• Lower capacity
TXV Stuck Closed (or Restriction)
• High superheat
• High subcooling
• Low suction
• High discharge pressure
TXV Stuck Open
• Low superheat
• Low subcooling
• High suction pressure
TXV
Suction
Line
Discharge
Copeland
Ultratech
Compressor
Bulb Upstream
of Equalizer Line
Proper TXV Bulb Placement
TXV
Basic Refrigeration Summary
A-H
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