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HVAC School - For Techs, By Techs

Dec 24, 2020

In this podcast episode, Bryan and Trevor Matthews from Emerson talk through scroll compressors in commercial refrigeration equipment.

Scroll compressors are not a monolith; although they all function similarly, they have different fine details and manufacturing protocols by application. Low-temp, medium-temp, high-temp, and A/C scroll compressors each have unique designs, operating conditions, and service considerations.

Copeland has a medium-temp scroll compressor line (ZB and ZS) for medium and high-temp applications. They also have a low-temp line (ZF). Within those lines, there are also small displacement and large displacement compressors, advanced scroll temperature protection devices, and other unique features.

Since scroll compressors are prone to thermal overload, some Copeland compressors have advanced scroll temperature protection devices. These devices help redirect the discharge gas to the suction gas, which gets the compressor to trip out on thermal overload more quickly. In cases when you're tempted to condemn the compressor, shut it off and let it cool down before you jump to conclusions.

The compression ratio is the main difference between A/C and refrigeration scroll compressors. A/C scrolls can handle a compression ratio of 11:1. Conversely, refrigeration scrolls can handle 26:1 compression ratios.

Copeland scroll compressors also have electronic controls. When setting up these controls, you need to keep the scroll compressor type and special features in mind, including temperature protection devices. In other words, you can't set up a low-temp compressor the same as a medium-temp and so on.

Bryan and Trevor also discuss:

  • Differences across Copeland scroll compressors
  • Low-temp vs. medium-temp vs. high-temp refrigeration
  • Copeland compressor nomenclature
  • Compressor pump down
  • Proper vacuum
  • CoreSense diagnostics
  • Vapor injection and compressor capacity
  • PTC (positive temperature coefficient) thermistors
  • Using AE bulletins as tools
  • Crankcase heaters and other accessories

Learn more about Refrigeration Technologies HERE.

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