Can I use geothermal heating and cooling in my existing home?

| by Gary Wollenhaupt
Can I use geothermal heating and cooling in my existing home?

Geothermal heating and cooling is one of the top ways homeowners can reduce their utility bills as well as their environmental impact. But for many years, geothermal was considered primarily an option for new construction.

As the housing market has changed and technology has improved, geothermal heating and cooling has become a viable option for existing homes.

A geothermal heating and cooling system is also known as a ground-source heat pump. Instead of the more common air-source heat pump, a geothermal system relies on the stable, even heat of the earth to provide heating, air conditioning and, in most cases, hot water.

A system of tubes buried horizontally or vertically in the ground contains a water/anti-freeze mixture that circulates through the ground and the heat pump. The antifreeze mixture carries heat to or from the home as needed. In some cases an open-loop system using a ground-water source may be possible depending on water quality and quantity.

Manufacturers such as Enertech offer geothermal products for retrofit situations with a minimum of alterations. In a home with an existing forced-air system powered by propane, heating oil or natural gas, a geothermal system can use existing ductwork and mechanical spaces.

If the existing furnace or boiler in a home is 20 years old or more, it may make sense to replace it with a geothermal system. If the current system  has a pilot light, it was likely installed prior to 1992 and has an efficiency of roughly 65 percent.

Geothermal systems are 400 percent to 500 percent efficient, so the operational costs will be significantly reduced. If the furnace is 10 to 20 years old, and has growing maintenance costs or does not heat or cool the home comfortably, an experienced dealer can help evaluate the wisdom of upgrading.

Get the benefits of geothermal in your existing home

Compared to a typical forced-air furnace, a geothermal system provides for more even heating and cooling. Homeowners don’t experience the temperature extremes between the times the furnace turns on and off. Instead, the geothermal system runs longer but with less intensity, making for a comfortable, quiet setting in the home. Surveys by utilities have found that more than 95 percent of all geothermal heat pump owners would recommend a similar system to their friends and family.

Improved comfort can also mean lower operating costs. Actual savings depend on the climate where the home is located, local energy rates and the thermostat settings. However, studies from the U.S. Environmental Protection Agency indicate that most homeowners will see a reduction of 30 percent to 40 percent in their heating and cooling costs. In addition, the EPA reports that geothermal systems have the lowest life- cycle cost of all heating and cooling systems on the market.

A study completed in the 1990s demonstrated the environmental benefits of installing a geothermal system. This research compared the carbon dioxide emissions of a standard 3-ton residential geothermal system versus a conventional fossil fuel system. The study found that the geothermal system produced approximately one less pound of carbon dioxide per hour of use. Extrapolating this data to 20 years of use equates to the environmental impact of planting 120,000 acres of trees or converting approximately 58,000 cars to zero emission vehicles.

Geothermal solutions for existing homes

For a retrofit situation, the geothermal split system creates a hybrid heating system in the home by adding geothermal to an existing furnace. In this case, the existing furnace acts as a backup system for extreme temperatures. The geothermal heating coil fits above the existing furnace, and is connected to a remotely located geothermal compressor section to provide all of the cooling and the majority of heating. In older homes this is a more cost-effective solution compared to increasing the electric service capacity necessary for an all-electric system. If the home is undergoing major renovations, or the furnace is being replaced, then an all- electric system can also be an option.

In addition, geothermal systems can be equipped with a device called a "desuperheater" that heats household water, which circulates through the regular water heater tank. In the summer, the heat taken from the house is used to heat the water for free. In the winter, the desuperheater can reduce water-heating costs by about half, while the conventional water heater meets the rest of the household's needs. In the spring and fall when temperatures are mild and the heat pump may not be operating at all, the regular water heater provides hot water.

Is your home right for geothermal?

One of the biggest differences -- and expenses -- of a geothermal system compared to a traditional heating and cooling system is the ground loop. Typically the ground loops are buried under the frost line of the ground around the house. The loops are made of high- density polyethylene pipe and filled with a water and antifreeze solution before being connected to the heat pump. The home must have sufficient land for the ground loops for horizontal placement. Vertical placement is typically more expensive than horizontal but requires less space. Depending on the location, other options such as a loop sunk in a nearby pond are available as well.

The geothermal heat pump typically costs about the same as a high-efficiency gas furnace and central air conditioner, but has a longer service life. The additional cost of digging and installing the ground loops is the incremental cost over a furnace/air conditioner system. The ground loop cost is offset by the lower energy costs, and becomes a permanent part of the home's property.

Also, as part of the American Reinvestment and Recovery Act, the United States federal government allows a 30 percent tax credit for Energy Star- qualified geothermal systems (including the ground loop) installed before Dec. 31, 2016. Additional incentives may be available from state or provincial governments and local utilities. With the tax incentives, a geothermal system can pay for itself in a reasonable amount of time, according to Melissa Rappaport Schifman, a green homebuilding consultant and blogger.

“I have generally seen a four-to-six year payback for homeowners,” she wrote.

To ensure that a geothermal system adds value to your home and comfort in your life, consult a qualified dealer that will help plan your system and choose the equipment that makes sense for your situation.

Read more about geothermal heating and cooling for your home.

Topics: Geothermal Heating & Cooling, Rebates / Tax Credits

Companies: Enertech Global, LLC

Gary Wollenhaupt

Gary Wollenhaupt is an experienced writer and editor, with a background as a daily newspaper reporter as well as corporate and agency public relations and marketing. He is constantly looking for affordable green upgrades to make to his home in eastern Kentucky.

wwwView Gary Wollenhaupt's profile on LinkedIn

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