Is a Geothermal Heat Pump Right for Your Home?

When you think of geothermal heat pumps, you likely think about heating your home, not cooling it, too. But, with this type of system, the process is very similar, just in reverse. 

For cooling, a geothermal system works by basically using the earth (or a suitable body of water) as a giant heatsink. It’s a heat exchange system that uses the constant temperature of the earth to generate or expel heat.

How Does a Geothermal Heat System Work? 

Geothermal heating and cooling uses the relatively constant temperature of the earth to either heat or cool your home. These systems essentially function as a multi-functional HVAC system that can heat your home with forced air or radiant heating, cool the temperature in hot weather, and deliver hot water. 

Liquid, usually water or a mix of water and antifreeze, travels through the heat pump. The heat pump transfers hot air from your home and into the liquid, which travels through a system of pipe loops buried around in the ground where it gets dispersed into the earth. 

The liquid then continues on its loop back to the heat exchanger, or heat pump, ready to be loaded with more unwanted heat.

Does a Geothermal Heat System Also Work as an AC?

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Yes, even in the hottest climates, a geothermal system functions as a highly efficient, environmentally friendly air conditioning unit. 

That's because, however hot the air temperature is, a few feet down, the earth remains at an average temperature of approximately 55 degrees Fahrenheit, even if the temperature above ground exceeds 100 degrees.

What Are the Parts of a Geothermal Heat System?

A geothermal system contains just a few simple but crucial elements. Above-ground components have a life expectancy of around 25 years, while underground components typically last for around 50 years.

Distribution System

The distribution system is usually a forced air system when used for cooling as well as heating. With forced air, an air handler is affixed to the ductwork in your home to transfer cooled air to the living space. 

Heat Pump

The heat pump is where most of the magic happens. This unit contains the compressor and condenser, the expansion valve, and the evaporator coil. The compressor increases the temperature of the refrigerant by increasing the pressure it's under. 

Now hot and pressurized, the liquid journeys into the condenser, where it transfers its heat to the fluid in the ground loops. While the refrigerant now travels onward to the expansion valve, the heat that was delivered to the ground loops works its way through those underground pipes where it's dispersed into the earth. 

When it meets the expansion valve, the refrigerant decreases in pressure and therefore temperature. It now continues on to the evaporator coil where heat from inside your home is transferred into the refrigerant and the cycle begins again.

Geothermal Loops

The geothermal loops are the pipes that sit underground or underwater. The most common type of geothermal system is a horizontal one, where the property has enough outdoor space to accommodate the long runs of pipework. In this case, the pipes are buried between 4 and 8 feet deep, depending on where the frost line is. 

If outdoor space is very limited, then you can opt for vertical installation, but to install a geothermal heating and cooling system with vertical loops costs much more, as the pipes require the contractors to dig down to around 300 feet. 

Another viable option is to use a body of water. If you have a large pond on your property, within 100 feet of your house, you may be able to anchor your geothermal loops on the bottom and use that as an aquatic heatsink.

What Are the Benefits and Disadvantages of Geothermal Cooling Systems?

While there are many benefits to geothermal heating and cooling systems, not the least of which is the cost savings and environmental-friendliness, there are some disadvantages, too. It's important to have the full picture so you can make an informed decision as you explore your options.