In this podcast episode, Bryan and Trevor Matthews of Emerson Canada discuss the Copeland 2-stage ZPS scroll compressors. Please join us by following along in bulletins AE4-1428 and AE4-1365. The ZP91KCE to ZP143KC Copeland compressors don't have internal pressure reliefs (IPRs). Those higher-pressure compressors make very loud noises when they go off, and it'll blow hot discharge gas on the internal overload to shut down the compressor. Some scroll compressors have temperature operating disks (TODs), which are bimetal disks that open upon a temperature increase and reroute the gas. Other compressors have advanced scroll temperature protection (ASTP), which is a snap-back disk near the floating seal. You don't just want to shut the suction service valve to pump the scroll down. Instead, common service procedures include checking voltage to the compressor, the internal motor, the blower/fan operation, the suction pressure, and the compressor wiring. If you install crankcase heaters for oil management, be sure to install them correctly to avoid overheating the compressor. You'll also want to verify that crankcase heater voltage and ensure that it is properly grounded. Two-stage modulating Copeland scrolls work with a 24v DC solenoid in the scroll set. That solenoid energizes and de-energizes, which either fully or partially loads the compressor. Load matching is ideal for efficiency and comfort, meaning that the two-stage Copeland scrolls perform well in those areas. Unsurprisingly, the fully-loaded option draws more current than the partially-loaded option. These two-stage compressors don't have IPRs, so you will need a high-pressure control set to 650 PSI. Trevor and Bryan also discuss: TOD vs. ASTP Operating envelopes Hipot testing Single-phase compressors Using Copeland compressors in pool heaters Oil and refrigerant dilution Wiring up CoreSense Reversing valve sizing issues Visit climate.emerson.com for more resources. Learn more about Refrigeration Technologies HERE. If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.