Geothermal Heat Pumps

You can use the energy found in the earth to heat and cool your home. A geothermal heat pump is an electrically powered device that uses the natural energy stored in the earth and/or the earth’s ground water to heat and cool your home or business. These are the most energy efficient heating/cooling systems on the market.

How does it work?

Like any type of heat pump, it simply moves heat energy from one place to another. Similar to the way a refrigerator works. The earth absorbs and stores energy. Heat is extracted from the earth through a liquid medium (groundwater or an antifreeze solution) and is pumped to the heat pump or heat exchanger. There the heat is used to heat your home. In the summer, the process is reversed and indoor heat is extracted from the home and transferred to the earth through a liquid.

Steps to installing a geothermal heat pump

• A heat loss/heat gain calculation needs to be done by your contractor  (This determines the size of system you will need.)
• Your site needs to be evaluated to determine best system for you.
• Gather bids from different contractors.

Type of Systems Available

To determine the best system for you, your site will need to be evaluated. There are two types of geothermal systems- each having several options available. These systems can be installed in new homes very easily or current systems can be retrofitted.

Closed Loop System

The term “closed loop” is used to describe a geothermal heat pump system that uses a continuous loop of special buried plastic pipe as a heat exchanger. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which water and an antifreeze solution is circulated. Unlike an open-loop system, it recirculates its heat-transferring solution in pressurized pipe.

Does the buried pipe system really work?

The buried pipe, or “ground loop”, is the most recent technical advancement in heat pump technology. The idea to bury pipe in the ground to gather heat energy began in the 1940’s. But it’s only been in the last 20 years that new heat pump designs and improved pipe materials have been combined to make geothermal heat pumps the most efficient heating and cooling system available.

There are several types of loop configurations:

Horizontal

Closed loop, horizontal configuration 

 

Vertical

Closed loop, vertical configuration  

Pond

Closed loop, pond configuration  

Closed loop systems should only be installed using high density polyethylene or polybutelene pipe. Properly installed these pipes will last 25-75 years. They are inert to chemicals normally found in the soil and have good heat conducting properties. PVC pipe should not be used under any circumstances.

How are the pipe sections joined?

The only acceptable method to connect pipe sections is by thermal fusion. Pipe connections are heated and fused together to form a joint stronger than the original pipe. Mechanical joining of pipe for an earth loop is never an acceptable practice. The use of barbed fittings, clamps and glued joints is certain to result in loop failure.

The Open Loop System

The term “open loop” is commonly used to describe a geothermal heat pump system that uses groundwater from a conventional well as a heat source. The groundwater is pumped into the heat pump unit where heat is extracted, then the water is disposed of in an appropriate manner. Since groundwater has a relatively constant temperature year round, it is an excellent source of heat.

You must have a large volume of water to use an open loop system. You typically need about 7-15 gallons of water per minute. This will depend on the size of system required to heat your home. The water can be pumped from one well to another well or pond. This replenishes the aquafer. The only thing that happens to the water is that heat is taken from the water or injected into the water.