What is a ground-source heat pump?
Ground-source heat pump (GSHP) systems, also referred to as geothermal, use the constant temperature of the earth to transfer heat to and from your home.
In the heating mode, GSHP systems transfer heat using a loop system installed in the ground. Heat energy is carried into the home through piping connected to and powered by a heat exchange unit inside the home. In the summer this process is reversed to transfer heat from the home into the ground. A GSHP may also be used for water heating at no or very little additional cost.
Benefits of a GHSP
- Up to 4x more efficient than a conventional heating and cooling system.
- Allows for design flexibility and can be installed in both new and retrofit situations.
- Can reduce "hot" water costs by using a "desuperheater" component to pre-heat your hot water system.
- Eliminates noise pollution outdoors because there is no outside unit.
Ground Source Heat Pump Loop System
There are four types of ground source loop systems; vertical wells , horizontal (trenching), horizontal (boring), and pond/lake systems. All four are called “closed loop” systems because the fluid used in the loops is constantly recycled.
The most common of the four loop types is the vertical wells, which uses a drilling rig to "drill" deep holes in the ground that the loop pipe is housed in. The holes are then backfilled with bentonite grout so that there is good thermal contact between the pipe and the ground. One major benefit of using a drilling rig is that it will work in most soil conditions such as hard clay and rock.
Discuss with your contractor what loop system will work best for you and your home. Though all the systems listed above will work for your ground source heat pump there are advantages and disadvantages with each.
Frequently Asked Questions:
Q: Is a ground source heat pump the same thing as a geothermal heat pump?
A: Yes, ground source systems often are referred to as geothermal systems, since both use the earth as a heat source.
Q: What are the components of a GSHP system?
A: There are three: the heat pump unit; the liquid heat exchanger medium (the closed-loop pipe system); and the air delivery system (ductwork).
Q: Will my existing ductwork function with this system?
A: Ground Source Heat Pumps generally move a higher volume of air compared to traditional electric resistant or gas systems. This higher volume of air may need bigger ductwork than what is currently installed in your home. If your duct is too small for your system it could lead to air flow and noise issues. Your dealer/installer will be able to determine ductwork requirements and minor modifications needed, if any. Ductwork must be installed in homes that don't have an existing air distribution system and the difficulty of installing or modifying ductwork will vary and should be assessed by a contractor.
Q: How large are the indoor components of a GSHP system?
A: The GSHP system used for most residences generally has the same footprint of a standard washing machine.
Q: Do I need to increase the size of my electric service?
A: GSHPs don't use resistant heat in general operation so your existing service may be adequate. Generally, a 200-amp service will have enough capacity, and smaller amp services may be large enough in some cases. Your electrical utility or contractor can determine your service needs.