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Should you install a geothermal heat pump?

Posted on: September 17, 2010

By now you’ve probably heard all about geothermal heat pumps –how efficient they are, how much money they can save you, etc. But geothermal heat pumps are very expensive. How do you decide if a geothermal heat pump is right for your Montgomery County, Maryland or Washington, DC home?

Economics of geothermal heat pumps

Geothermal heat pumps have a high initial investment, but they save money in operating and maintenance costs. Geothermal heat pumps units typically cost $2,500 per ton of capacity. Most residential units cost $7,500 (3 tons). Installation costs on geothermal heat pumps can be very expensive too, often ramping the price up to $20,000. This may seem very expensive, but when added onto an existing 30 year mortgage, it will come out to roughly an extra $60 a month. Your monthly energy savings will be greater than that.

In addition to huge utility savings each month, your geothermal heat pump can be fitted with a device called a “desuperheater.” This device will enable your geothermal heat pump to heat water as well, providing hot water for free in the summer and for about half the cost in the winter. Energy savings with a geothermal heat pump are so great that most people see payback periods of five to six years – pretty impressive when you consider a geothermal heat pump will last around 50 years.

In addition to energy savings, many areas offer discounts, rebates and tax breaks on the installation of new geothermal heat pumps. In fact, through the end of 2010 the federal government is offering a tax credit worth 30% of the total cost of your geothermal heat pump installation, which reduces the payback period even more.

Evaluating your property for geothermal heat pump installation

Shallow ground temperature is relatively consistent throughout the United States, meaning that a geothermal heat pump can be used almost anywhere. That said, there are a number of considerations to be made when choosing a system.

The most important thing to consider when installing your new geothermal heat pump is the composition and properties of your soil and rock, as these can affect heat transfer rates. Soil with good heat transfer properties will require less piping than soil with good heat transfer properties. Your soil composition will also determine what kind of loop you should install – if your soil is too rocky and shallow to trench, a vertical loop may be installed as opposed to a horizontal loop.

Water availability, both ground and surface, is also a big factor in determining how your geothermal heat pump will be installed. If possible, surface or ground water bodies can be used to install an open-loop system (which pumps in new water instead of having a constant supply). Before you install an open-loop system, check to make sure you have a large enough water source and that the water quality is suitable.

Land Amount
The amount and layout of your land and the location of your underground utilities also affects your geothermal heat pump design. Horizontal ground loops, which are generally easier to install, work best with new construction or with sufficient land space. Vertical loop systems or horizontal “Slinky” installations are usually installed on existing property because they minimize land disturbance.

Installation of a geothermal heat pump

Installing a geothermal heat pump requires in depth technical knowledge and heavy duty equipment and should not be attempted by anyone other than a professional. Ground loop geothermal heat pump systems are made with high density polyethylene pipe that is buried four to six feet deep (for horizontal closed loop) or 100 to 400 feet deep (vertical closed loop). The piping is filled with an environmentally friendly water/refrigerant solution which acts as the heat exchanger. The air delivery ductwork operates the same way that it does in a conventional system.

If you think you are ready to install a geothermal heat pump in Gaithersburg, call James A. Wheat & Sons today. Our certified trained technicians can evaluate your property and help you make the best decision for your investment.