Outdoor air temperatures fluctuate throughout the year with the changing seasons. In contrast, ground temperatures about four to six feet below the earth's surface remain relatively moderate and constant all year. That's because the earth absorbs 47% of all the heat energy that reaches it's surface from the sun. A geothermal system circulates a water-based solution through a buried loop system to take advantage of these constant temperatures. A single piece of equipment has the ability to heat and cool a home, while providing some or all of the home's hot water as well.
We have a closed-loop system. The term "closed-loop" is used to describe a geothermal heat pump system that uses a continuous loop of high-density polyethylene pipe as a heat exchanger. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which ethyl alcohol (an anti-freeze solution) is circulated. Our application consists of eight 300-foot lengths of parallel pipe spaced one foot apart and buried five feet beneath the surface of the earth.
The anti-freeze solution (ethyl alcohol) leaves the ground loop at approximately 10° C (50° F) and enters the heat pump and the first heat exchanger (evaporator). The (EarthPure® R-410A) circulating through the heat pump has a very low boiling point and when it enters the evaporator the temperature of the anti-freeze solution is high enough to boil the and turn it into gas. The anti-freeze solution leaves the heat pump at about 8° C (46° F) and returns underground. The refrigerant, now in gas form, passes through the inversing valve which directs it into a small compressor. The pressure increases the temperature of the refrigerant from 10° C (50° F) up to 45-50° C (113-122° F) in the compressor. The hot gas then enters the second heat exchanger (de-superheater) where it transfers some heat to the supply for the domestic hot water heater, effectively pre-heating the water. The hot gas returns to the inversing valve and is directed to the last heat exchanger (condenser) where it passes through a fan convector. This process extracts heat from the hot gas changing it into a hot liquid. The hot liquid passes through an expansion valve which causes a sudden drop in refrigerant pressure and temperature, returning the refrigerant to a .
The anti-freeze solution (ethyl alcohol) leaves the ground loop at approximately 10° C (50° F) and enters the heat pump and the first heat exchanger (evaporator). The refrigerant (EarthPure® R-410A) circulating through the heat pump as a hot gas transfers heat to the anti-freeze solution which lowers the temperature of the refrigerant and changes it from gas to liquid. The anti-freeze solution leaves the heat pump at about 12° C (54° F) and returns underground. The refrigerant, now a hot liquid, passes through an expansion valve which causes a sudden drop in refrigerant pressure and temperature, changing the refrigerant to a . The refrigerant then enters the fan convector where the cool air lowers the temperature in the house (air conditioning). During this process the temperature of the refrigerant rises (boils) and it turns from into gas. The cool gas passes through the inversing valve which directs it into a small compressor. The pressure increases the temperature of the refrigerant from 10° C (50° F) up to 45-50° C (113-122° F) in the compressor. The resulting hot gas then enters the second heat exchanger (de-superheater) where it transfers heat to the supply for the domestic hot water heater, effectively pre-heating the water. The hot gas returns to the inversing valve and is directed back to the evaporator where it transfers heat to the anti-freeze solution and becomes liquid again.
The installation took place over four days. The first day the ground was excavated and the ground loops were laid. The second day a trench was excavated from the ground loop bed to the house. The ground loop was connected to inlet and outlet pipes. The system was pressurized, tested, and then backfilled. The third day the heat pump was installed, and the fourth day the system was connected and tested.
Day 1 – Installing the Loop
Day 2 – Connecting to House
Day 3 – Installing Heat Pump
