If you’re interested in helping to protect our environment and at the same time, drastically lowering your utility bills, a geothermal heat pump is definitely worth consideration. Called by some as the “greenest” way to heat and cool your home, geothermal heating and cooling is growing by leaps and bounds across the nation. Airtech is proud to offer this as one of our green energy options!
To understand how a geothermal heat pump (GHP) works, you must understand the basics of heating and air conditioning. Keeping your home comfortable is all about one thing: moving heat energy. In the summer, your air conditioner doesn’t blow cold air into your home. It compresses and chills refrigerant, pumps the chilled liquid inside, and this is used toabsorb heat energy from your inside air. In the winter, a gas furnace or other heating source adds heat energy back into your air.
A GHP trumps normal heating and cooling systems by using ‘earth loops’ buried deep in the ground (or adjacent body of water). These earth loops contain a fluid (like refrigerant). In the summer, heat energy is pulled from the home, and dissipated into the thermal layer underground — more effective than an air conditioner dissipating heat energy into the outside air. In the winter, temperatures at 6-8 feet underground in Minnesota remain a stable 46-52 deg. F. The earth loops extract heat energy and use this to heat your home.
Trenches several hundred feet long are excavated. Minnesota frost depths range from 4-7 feet, so the trenches are at least 2 feet deeper than the deepest annual frost. A typical horizontal earth loop will be around 500 feet for each ton of cooling. Once the loops (piping) are often installed coiled as to save on the length of the excavation. Then the trench is back-filled.
If land space is not available for a horizontal loop, vertically-bored loops are an option. These are typically the most expensive to install however, but are sometimes the only option due to available space or site geology. The general practice is one bore hole per tonnage, and the hole will go down up to 250 deep with a 15-25 foot spacing between loops.
An ice-covered pond or lake might not seem like the ideal place to go for heat energy in the winter, but guess what – this can be a very efficient geothermal installation! Loops are installed on the bottom of the body of water which, even when there is ice above, remains at around 39 degrees. As heat energy is removed from the water it cools and rises, ushering in warmer water.
The other loop installations discussed are closed loop systems. The anti-freeze fluid is cycled through the loops year round. An well water loop is call an open loop because it simply draws water from deep underground, and after the water is “used” it is discarded. This system is simpler in design, and doesn’t require the same about of earth loops to function.