Trevor Matthews from Refrigeration Mentor comes on the podcast to talk about Copeland reciprocating CS compressors. He and Bryan cover Bulletin AE4-1433 (found HERE) as they look at the operating envelopes for the CS compressor.

The CS compressors are hermetic reciprocating compressors that can work with some of the newer refrigerants. You will likely see these compressors in applications with smaller tonnages.

You'll usually want to charge these compressors with liquid refrigerant. If you have more than 6 pounds of charge in the system, using an accumulator is recommended. Under those charge conditions, the system also needs a check valve between the receiver and the condenser.

Suction line pressure drop is one of the most important things to pay attention to in the system. Make sure the suction line is of an appropriate size, that filter-driers don't have restrictions, and that accumulators aren't clogged. Overall, many manufacturers recommend removing the duction driers to keep the pressure drop minimal.

The recommended runtime for these compressors is also very short, only 5 minutes. CS compressors should cycle no more than 12 times per hour, and the off-time between cycles should be a minimum of 10 seconds.

Before returning or replacing a compressor, make sure you check all of the electrical components, including the capacitor. If the compressor hums but has power, you could simply have a capacitor or potential relay issue.

Trevor and Bryan also discuss:

• Return gas temperatures
• Discharge line temperature
• Compressor superheat and flooded conditions with refrigerant blends
• Crankcase heaters
• Pump-down recommendations to stop short cycling
• Initial charge vs. recharge
• Metering devices
• Line sizing
• Electrical shorts
• Sticking relays
• Single-phase vs. three-phase power
• Megohm testing
• Purging with and flowing nitrogen
• Burnout cleanup procedures
• Locking/tagging out equipment
• Hard start kits, potential relays, and start capacitors

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