Geothermal Heat Pumps: What you Need to Know

You might have read or heard about geothermal heat pumps and how they’re gaining a lot of popularity. But what does “geothermal” mean and how does this system work?

Geothermal heat pumps work along the same principles as standard air conditioning or heat pump systems with a few exceptions:

Drawbacks of standard air conditioning

Standard central air conditioning systems typically consist of two parts, an indoor and outdoor unit. The indoor and outdoor sections rely on air being forced across their coils in order to transfer heat to the surrounding area.

  • One drawback to this design is that the system can meet limitations as the outdoor temperature reaches extremes. This is most common with a standard heat pump system in winter. As the outdoor temperature drops below 25°F, it reduces the heat pump’s ability to return air to the system at the proper temperature.
  • A geothermal unit avoids this scenario by using water, which is much better at retaining a consistent temperature, instead of air.

The heat exchanger

The components found in a typical geothermal system closely resemble that of a heat pump system. Components like the compressor, metering device, and indoor coil all perform the same basic functions. One important exception is that the outdoor fan coil has been replaced in a geothermal system by a heat exchanger.

  • A heat exchanger, as the name suggests, takes heat from the system’s refrigerant and transfers it to circulating water.

The geothermal cooling system in action

When cooling is needed, the system’s compressor pumps refrigerant through the metering device and into the indoor coil. The heat from the house is then transferred to the refrigerant, thus cooling the air. The air is then returned to the house through the air ducts.

The heat transfer that took place in the indoor coil travels by way of the refrigerant through the geothermal system to the heat exchanger. This heat trapped in the refrigerant is then released to water in the heat exchanger. As this happens, the water becomes heated and the refrigerant, once again becomes cool. This now heated water is pumped through a series of underground pipes located externally to the house. While the heated water moves through this piping loop, it releases the heat back to nature and the cool water returns to the system.

Why outside air temperature is irrelevant

Traditional air conditioners must take very hot outside air and work hard to cool it. By locating the piping loop in the ground, the outdoor ambient temperature does not affect the geothermal system’s temperatures required for heating and cooling. This design allows for geothermal systems to provide a very high level of system efficiency for either cooling or heating, regardless of how hot or cold it is outside.

Did you know you could save so much energy getting your heating and cooling from the ground instead of the air?

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3 thoughts on “Geothermal Heat Pumps: What you Need to Know

  1. Hi Lynn – we discussed this and decided you might be able to use this for your geothermal loop but you should ask the contractor to check for the thermal properties to see if it will provide enough surface area for your system. They should also check the pH or acidity level of the water to make sure that does not cause problems down the road. I hope this helps answer some of your questions.

  2. I have a capped off well that has not been open in over 50 years. I have heard that you can use the well in a geo thermal system and will save cost in digging underground etc. is this true?

  3. Really liked what you had to say in your post, Geothermal Heat Pumps Guide, thanks for the good read!
    — Hassan

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