Residential Geothermal Energy Heat Pumps

The term geothermal literally means Earth/Ground (Geo) Heat (thermal). Geothermal, or ground source heat pumps, take advantage of the constant ground or groundwater temperatures.

A refrigerant loop with a compressor extracts heat from one side (the ground) and “pumps” it to the heating loop in your home. It is essentially the same process that happens in your refrigerator: “heat” is extracted via a compressor and refrigerant loop from the inside of your refrigerator/freezer and rejected into your house.

In the summer the geothermal heat pump reverses its cycle, if you have an air-conditioning system, and heat from the home is rejected into the ground or ground water.

What makes geothermal heat pumps such a good and reliable choice is that they do not depend on outside air temperatures. These heat pumps will heat your home as efficiently on a windy, zero-degree winter day as on a 40-degree day. Provided of course, that your house is well insulated and tight.

Geothermal heat pumps are also a very efficient way for heating and cooling your home. They use 25-50% less energy than conventional heating and cooling systems (Source: US DOE)

Residential applications of geothermal energy systems use water-to-water or water-to-air heat pumps.

Water-to-Water Geothermal Heat Pumps

Water-to-water geothermal heat pumps are generally used for heating only. They replace the gas or oil furnace that you might currently have to heat your home and water with.

It is important to know that heat pumps work most effectively when the temperature difference between the heat source (ground) and heat sink (floor heat or radiators) is small.

Ground temperatures range anywhere from 50 to 75 degF, depending on where you live. This means that geothermal heat pumps are generally not suitable for standard hot water baseboard applications, which are designed for heating water temperatures of 180 degF. Floor heat and low-temperature radiators require water temperatures in the range of 95 to 140 degF.

Some newer heat pump models are now equipped with “desuperheaters” (don’t you love those technical terms!) that can transfer excess heat from the geothermal heat pump compressor to the domestic water heater. Your geothermal heat pump can then also effectively and quickly heat water for your bathtub, shower and sinks.

Water-To-Air Geothermal Heat Pumps

These types of ground source heat pumps are generally used when you need air conditioning. The “water” is the heat sink, where you reject the heat from the house. The “Air” is the air that is distributed through your home via ductwork.

Otherwise, thse heat pumps function the same way as water-to-water heat pumps. And again, the efficiency of a geothermal heating and cooling system is far better than that of a traditional system.

Important To Know

The first step towards making a geothermal heat pump system be a reliable and efficient heating (and cooling) system for your home is to minimize the heating and cooling requirements with a well-insulated building envelope and strategically placed windows for passive solar gain.

Not only is your first cost reduced, because your system will be smaller. You will also tremendously increase the comfort of your home.

Geothermal heat pump systems are best designed and installed by professionals. It is not recommended to DIY. Check at the Geothermal Heat Pump Consortium for a list of certified installers.

Additional Information

The US DOE has published “Geothermal Heat Pumps Make Sense for Homeowners“, a PDF file you can download and print out.

You can find tons of technical information on how exactly heat pumps work at the following links, if you are technically inclined and want to educate yourself on the topic of heat pumps:

US DOE Energy Efficiency and Renewable Energy site
IEA Heat Pump Centre
Sunteq GEO Distributors have been designing and installing heat pumps for over 20 years

If you are interested in other alternative energies for your green home:

Solar Energy Basics
Wind Power Generators
Heating With Wood

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Tags: Geothermal Energy, geothermal diy, geothermal heat pumps, geothermal heating and cooling, renewable energy