Heat pump schematic (C) Carson Dunlop Associates Groundwater Heat Pump System Efficiency Measurements

  • HEAT PUMPS, GROUNDWATER - CONTENTS: Heat Pump Efficiency. easurements - Compare COP's and EER's of groundwater heat pump systems. Ground coupled heat pump system efficiency measurements. Groundwater source heat pump systems & thermogeology. Books on geothermal heat pumps
  • POST a QUESTION or READ FAQs about measuring the performance efficiency or operating cost of ground water heat source heat pumps
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Groundwater heat pump coefficient of performance COP and energy efficiency measurements.

This article discusses efficiency measurements of ground coupled heat pump systems: COP's and EER's. Also see our list of heat pump inspection, diagnosis, and repair articles beginning at HEAT PUMPS.

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Heat Pump Efficiency Measurements

Groundwater Heat Pumps: confused about COPs and EERs


Several well-water heat pump manufacturers claim COP's of 3 to 6 and EER's of 13 to 17 [1986 data].

But the Air Conditioning and Refrigeration Institute (ARI) (cited at REFERENCES) list tested COP's of 2.6 to 3.4 and EER's of 9 to 14.

Who's right? - Howard W. Murray, Bowie, MD


You can't tell which COP and EER measurement for groundwater based heat pump systems is "right" without additional data describing the testing conditions, according to Atlanta-based engineer Don Abrams, author of "Ground Coupled Heat Pumps" [Solar Age Magazine, Sept. 1985].

See HEAT PUMP COP for a definition of heat pump COP or coefficient of performance and for comments about sources of variation in COP numbers.

At SEER RATINGS & OTHER DEFINITIONS we define EER, the Energy Efficiency Ratio for HVAC equipment.

The building's heating and cooling loads and incoming water temperature all affect the efficiency measurements of the heat pump system.

Another factor affecting measurement of a ground-coupled heat pump system's efficiency is the energy required to pump the water. this could, by itself, account for the groundwater heat pump efficiency measurement differences on the order reported in your question above.

ARI engineer David Feron says that for groundwater-source heat pump efficiencies to compare with ARI figures, testing has to be done in accordance with ARI [now AHRI, Air-Conditioning, Heating, and Refrigeration Institute] standard 325-85.

[Note: as of 2011 AHRI publishes the following standards for Water-Source & Ground Water-Source Heat Pumps]

The question-and-answer article about heat pumps, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. Adapted with permission. January 2011.

Geothermal Energy & GeoExchange or Earth-Coupled Ground-Source or Water Source Heat Pump Rules of Thumb

Current Energy Use measurements for heat pumps are expressed as EER or COP. The range of top performing heat pumps in 2017, according to the U.S. Department of Energy, can provider

Using current best ground source heat pump technology as of August 2017, to obtain one ton of heating or cooling energy a ground-source heatpump system will need a 100-foot deep (or long) hole into which a 1/4" or 1/2" tube of refrigerant will be looped. This data is for typical soil conditions found in the Hudson Valley such as Poughkeepsie, New York 12603.

Soil and site conditions that affect the cost and trouble of the soil drilling to install a geothermal energy system vary considerably by both geographic area and site specific conditions such as hitting buried boulders, convenient drilling location, angle, and depths available.

References on ground and ground water source heat pumps

Watch out, the geothermal and groundwater source heat pump articles just below are ridiculously expensive documents also available at

The question-and-answer article above paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. The link to the original Q&A article in PDF form immediately below is preceded by an expanded/updated online version of this article.


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