Heat Pump COP and Low Temp Lock Out

Author: Bryan Orr
Original Air Date: April 18, 2024
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This episode of the HVAC School Live Stream covers the key concepts around heat pump efficiency and understanding the coefficient of performance (COP). Eric Kaiser from TruTech Tools and Jim Fultz from White-Rodgers provide valuable insights into how heat pumps operate and how to optimize their performance, especially in colder weather conditions.

The discussion begins by exploring the COP of heat pumps and how it compares to the efficiency of electric resistance heat. A COP above 1 means the heat pump is delivering more heat for the same amount of energy input compared to electric resistance heat. Many homeowners mistakenly believe they should switch to emergency heat once the outdoor temperature drops, thinking the heat pump is no longer efficient. However, even at very low outdoor temperatures, a well-designed heat pump can still operate with a COP above 1, making it a more cost-effective heating option than emergency heat.

The conversation then delves into the concept of the thermal balance point, which is the outdoor temperature at which the heat pump can no longer meet the heating load of the home. The guests discuss how to calculate this balance point and how to set up controls to optimize the use of the heat pump and any supplemental heating sources, such as electric resistance heat or a gas furnace in a dual-fuel system. They emphasize the importance of proper air distribution and avoiding blowing cold air directly on the occupants, which can be a common complaint with heat pumps.

Key Topics Covered:

  • Coefficient of Performance (COP) and how it compares to electric resistance heat
  • Efficiency of heat pumps at low outdoor temperatures
  • Thermal balance point and how to calculate it
  • Optimizing control settings to balance heat pump and auxiliary heat usage
  • Importance of proper air distribution and avoiding blowing cold air directly on occupants
  • Considerations for dual-fuel systems with both a heat pump and a gas furnace
  • Best practices for programming thermostats and control systems to ensure optimal performance and comfort


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