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) 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].

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]

  • AHRI 320-1998: Water-Source Heat Pumps
  • AHRI 325-1998: Ground Water-Source Heat Pumps
  • AHRI 330-1998: Ground Source Closed-Loop Heat Pumps
  • AHRI 410-2001: Forced-Circulation Air-Cooling and Air-Heating Coils

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.

Current references on ground and ground water source heat pumps:

  • Geothermal HVAC, [Amazon.com] Jay Egg & Brian Howard, McGraw-Hill Professional; ISBN-10: 0071746102, ISBN-13: 978-0071746106, quoting:

    This definitive guide covers commercial and residential geothermal heating, ventilation, and air conditioning technologies and explains how to take advantage of their money- and energy-saving features. Geothermal HVAC: Green Heating and Cooling reviews the array of choices currently available, offers market values for systems based on varying options and conditions, and describes how to pair the best systems for each application and budget.

    Whether you're a contractor or a consumer, you'll find out what you need to know to implement a geothermal HVAC system in a retrofit or new construction project, and start benefiting from this sustainable, affordable technology.
  • Geothermal Heat Pumps: A Guide for Planning and Installing, [Amazon.com], Karl Ochsner, Robin Curtis, Earthscan Publications Ltd. (December 2007), ISBN-10: 1844074064, ISBN-13: 978-1844074068quoting:

    Geothermal Heat Pumps is the most comprehensive guide to the selection, design and installation of geothermal heat pumps available. This leading manual presents the most recent information and market developments in order to put any installer, engineer or architect in the position to design, select and install a domestic geothermal heat pump system. Internationally respected expert Karl Ochsner presents the reasons to use heat pumps, introduces basic theory and reviews the wide variety of available heat pump models.

    Expertly reviewed and adapted for the most geographically broad application possible, the book offers the reader valuable tips for planning and system control using data, graphics and tables from a growing and innovative market.
  • Residential Geothermal Systems: Heating And Cooling Using The Ground Below, [Amazon.com], John Stojanowski, Pangea Publications LLC (March 17, 2010) ISBN-10: 0981922112, ISBN-13: 978-0981922119. Quoting from Amazon.com reviews:

    Readers will learn how heat pumps are able to extract heat from relatively low temperature water circulating in ground loops and raise it to a temperature high enough to heat a home. They will also learn how to estimate the size of the heat pump required and the ground loop size as well for straight 2-pipe, 4-pipe, 6-pipe and Slinky loop configurations. This is important in order to verify that the installer correctly sizes the system. Both horizontal and vertical loop systems, for GX and DX, are covered.

    Some of the technical issues that are addressed include: Loop water flow rates and Reynolds Number, heat of extraction/rejection, heating capacity, desuperheater setup, open-loop/closed-loop, SCW, pond loops, DX, Manual-J, COP. The final chapter consists of a set of flowcharts guiding the homeowner to ask the pertinent questions needed for a successful installation.

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

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.

  • Q&A on Groundwater Heat Pumps - original PDF version, use your browser's back button to return to this page. Solar Age Magazine, September 1986.

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