OK, I know what you are thinking: “What in the world are ground source heat pumps?”  Well, let’s use a simple illustration: Take a metal rod and heat it until it is glowing. Take it out of the fire and set it aside for 1-2 hours. Could you pick it up without burning yourself? Sure – but what happened? Your 11-year old would say it ‘cooled off.’ But what REALLY happened?

Actually, what happened was that the heat in the metal rod was ‘transferred’ to the surrounding air. But suppose we reverse that: what if we devise a machine that would take a cold metal bar, extract the heat from the air surrounding it, and pump it into the metal. What would happen? The metal bar would get hot. This is exactly what ground source heat pumps do: they “pump” the heat – move it in a certain way. So, if ground source heat pumps work properly, they need a source of heat: either the surrounding air or — in the case of ground source heat pumps, the source of the heat is the heat from the ground or soil (we sometimes call them ‘geothermal heat pumps’).

So ground source heat pumps use the ground for heat – their ‘source’ for the heat is the ground. Other types of heat pumps (called ‘air source’ heat pumps) take heat from the air around them.

Ground source heat pumps can also be used to COOL a building – just reverse the process. It will now act like a refrigerator: ground source heat pumps take heat from inside and move it to the ground outside (even in the summer the ground is relatively cool – have you ever noticed?)

Again, the air source heat pump must move the hot air from inside to the hot air outside, and again the air source heat pump must work harder. So, whether you are trying to heat or cool a building, ground source heat pumps can usually operate more efficiently and result in a tremendous savings in utility bills.

Another great option for those using ground source heat pumps is to use it for heating hot water. Ground source heat pumps can be installed with an add-on device called a ‘desuperheater’ – this device partially heats your water. In summertime, when your air conditioner is running (and ground source heat pumps can double as air conditioners), the desuperheater will use some of the extra heat taken out by the air conditioning process to heat your hot water! So, in the summertime, your water will be heated for free!

In wintertime, part of the heating power of ground source heat pump is used to heat the water. If, in your home, your ground source heat pump operates most of the time (especially to cool things off in the summer) you can increase your efficiency and save lots of money in heating your water. Truly, ground source heat pumps are a modern miracle of engineering!

Ground Source Heat Pump

In a comparison of geothermal and air source heat pumps, each one has its benefits that are likely to sway your opinion of which is best for you and your home. Geothermal heat pumps are one of the highest efficiency type of heat pumps you can get for your home.

This Heat Pump Article outlines the differences in the two types of home heat pump, so you can decide which one makes the most sense for your heating and cooling needs.

Heat Collection in Geothermal and Air Source Heat Pumps

The primary difference in the two types of heat pumps is where they collect and release heat. An air source heat pump is fully above ground and collects heat from the outside air in the winter and dumps it outside in the summer.

A geothermal heat pump collects it using liquid in pipes buried underground or in some cases, submerged under water, dumping heat in the ground or water in the summer. For this reason, these units are sometimes referred to as ground source heat pumps

Geothermal Heat Pumps are More Efficient than Air Source Heat Pumps

Similar to a hybrid heat pump system, efficiency is the primary benefit of a geothermal heat hump. They are more efficient – meaning that they use less electricity to produce the heating and cooling – because the ground temperature is more stable than air temperature. In winter, they are collecting heat from the ground or water where temperatures are in the 50s to low 60s while air temperatures can be in the 40s and below.

In the summer, geothermal heat pumps are dumping the heat into that same 50-60 degree medium rather than into air temperatures that can be in the mid-80s and above.

Air Source Heat Pumps Cost Less to Install than Geothermal Heat Pumps

This is the main advantage for air source heat pumps. The exact cost of a heat pump will vary widely, but it is common for a ground source heat pump to cost 2-3 times more for installation. The reasons for the extra cost are the increased time and materials required. Systems require 150 to 400+ feet of pipe. They take several days to a week or more to install, with the use of an expensive excavator, while air source heat pump systems can be installed in less than a day in many cases.

What Type of Heat Pump is Best for You?

A geothermal heat pump is the best choice if having the greenest technology is your purpose. It can also be a cost-effective heating and cooling system over the long term. It may take 7-10 years or more to gain back the extra cost of the system in the form of lower utility bills, but you’ll enjoy 25% to 40% savings over an air source heat pump each year.

If you’re unsure how long you’ll be in your current home, or don’t want the immediate expense of a geothermal heat pump system, then a standard air source heat pump might make the most sense for you.

Comparison of Geothermal and Air Source Heat Pumps