What is Geothermal and how does it work?
Outdoor air temperatures vary greatly throughout the year while temperatures underground stay fairly constant. The earth absorbs and stores approximately 47% of the sun’s solar energy. As a result, the temperature of the earth four to six feet below grade is fairly moderate and stable. The underground temperature in northern climates is approximately 45° and in southern climates it is in the range of 70° year round. The geothermal system takes advantage of this stored energy by using it to provide the most energy efficient heating and cooling system available.
Rather than generating heat, a geothermal system transfers heat from one place to another. The heat exchanger, commonly referred to as a closed loop system, is buried in the ground and circulates a water solution through a series of pipes. This solution captures the stored solar warmth and delivers it back to the geothermal system located in the house. The geothermal unit then transfers the solar heat throughout the house using standard forced air ductwork or radiant floor heat to deliver comfortable indoor temperatures during the winter.
The same geothermal unit and heat exchanger will reverse this cycle during the cooling season to provide air conditioning. The system removes heat and humidity from the air, transfers and deposits that heat back into the earth through the same loop system.
The Science behind the magic
The heat exchanger, also known as the loop system, captures the stored solar energy in the ground and delivers it back to the geothermal system in the house. There are 4 different types of loops.
Your loop system is the heart of geothermal technology. Regardless of the option you select, it will deliver over 500% efficient comfort and savings for many years into the future. Your local geothermal dealer will help you select the proper loop system based on a site survey and by conducting a detailed energy analysis of your home. Installing a geothermal loop system is like getting a 70% discount on energy for the life of your home.
This is the most common loop used when adequate land area is available. Loop installers use excavation equipment such as chain trenchers, backhoes and track hoes to dig trenches approximately 6-8 feet deep. Trench lengths range from 100 to 300 feet, depending on the loop design and application.
This loop is used mainly when land area is limited and in retrofit applications of existing homes. A drilling rig is used to bore holes at a depth of 150 to 200 feet. A U-shaped coil of high density pipe is inserted into the bore hole. The holes are then backfilled with a sealing solution.
A pond loop is an option if a large body of water is available within approximately 200 feet of the home. A 1/2 acre, 8 to 10 foot deep body of water is usually adequate to support the average home. The system uses coils of pipe typically 300 to 500 feet in length. The coils are placed in and anchored at the bottom of the body of water.
This system can be installed if an abundant supply of high quality well water is available. A typical home will require 4 to 8 gallons of water per minute. A proper discharge area such as a river, drainage ditch, field tile, stream, pond, or lake must be present. Check your local codes for restrictions before selecting a specific discharge method.