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Inverter (variable-speed compressor)

An inverter heat pump uses a variable-speed drive to run the compressor at different speeds to match the load.

Editorial staffEdited by heatpumpwiki

History 1

An inverter heat pump has a variable-speed compressor. The federal test procedure defines a variable-speed compressor system as one with "a compressor that uses a variable-speed drive to vary the compressor speed to achieve variable capacities."Source 1

NEEP's cold-climate specification requires it: "Compressor must be variable capacity (three or more distinct operating speeds, or continuously variable)."Source 2 ORNL researchers note variable-speed heat pumps "can often run at 30-40% of their rated cooling capacity to reduce cycling losses."Source 3

See Variable-speed vs single-stage heat pumps.

Sources

  1. 1.10 CFR Appendix M1 to Subpart B of Part 430, Uniform Test Method for Measuring the Energy Consumption of Central Air Conditioners and Heat Pumps. Electronic Code of Federal Regulations (U.S. DOE rule). Accessed Oct 25, 2026
  2. 2.Cold Climate Air Source Heat Pump Specification, Version 4.0. Northeast Energy Efficiency Partnerships (NEEP). Accessed Oct 25, 2026
  3. 3.Field Study of Performance, Comfort, and Sizing of Two Variable-Speed Heat Pumps Installed in Occupied Homes. Oak Ridge National Laboratory. Accessed Oct 25, 2026

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