Geothermal 101
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This is Geothermal 101: By: Tim Uzar – Geothermal Systems Designs
Geothermal heating and cooling technology has been around for decades, but not many people use it—compared to a conventional heat pump, it’s 2x more expensive to install. But if you’re building a new house, installing a geothermal system will only cost a few thousand dollars more than a conventional system and can pay off big through reduced energy and upkeep costs.
A geothermal Heat Pump is nothing more than a Heat Pump. A common misconception is it uses water from the earth to heat and cool your house, it does not! It works on the same principles as a regular air to air heat pump. Firstly I’m going to explain how a Heat Pump works. Compression of any gas to a liquid state (any one remember their chemistry & physics classes?) generates heat. In this case the gas we use is called refrigerant. This high pressure refrigerant is then quickly discharged to a vapor state through the use of a nozzle called an expansion valve, the same way hair spray comes out of an aerosol can. That vaporized refrigerant is now really cold. This cold refrigerant is piped through a coil where air blows past it from your air conditioner unit and the cold is what you feel in the summer time coming out of your vents. Once this refrigerant leaves the coil it begins its journey again through the compressor that puts the refrigerant back into a compressed liquid state. Imagine putting the hair spray back into the can and pressurizing it again so that the cycle can start all over again. But wait. The compressor and the refrigerant are now really hot from all this work so the Heat Pump uses a fan to cool everything off. This is what you see sitting outside your house making all kinds of racket out side your bedroom window. In the winter time this process still happens but in reverse.
Now I need to explain the draw backs to Air to Air heat pumps explained above. The heat pump is trying to discharge heat to the outdoors in the summer and it’s trying to absorb heat from the outdoors in the winter. This is pretty easy to do on a nice day such as 70 degrees. This is when your Air to Air heat pump is working at its peak SEER rating. Any body bought an 18 SEER unit lately? Ok so imagine you have to go do some yard work on this 70 degree day. Not too bad right? It’s because your body can absorb heat from the outside if needed pretty easily and discharge heat pretty easily if you start sweating if needed. Now imagine you have to do this yard work on a 98 degree day or a 14 degree night, pretty tough. This is when your unit is working at a very poor SEER rating probably in the single digit range. Remember SEER ratings are achieved in a laboratory.
Geothermal units are heat pumps, but they do not use outdoor air to cool or heat the equipment. Geothermal systems use water from pipes that are installed in the ground. Looking back to the yard work scenario, imagine you finish up the yard work on that 98 degree day and your buddy starts fanning you off. This probably feels better than nothing but imagine how much better you would feel if you jumped in a swimming pool, instant relief. The same concept happens in the winter if it is 14 degrees outside, jumping in to a 68 degree swimming pool might not feel so bad after all.
Here’s how it works:
Water is pumped through a series of closed loop pipes installed (either in a vertical or horizontal position) in the ground. Unlike air, soil doesn’t experience dramatic swings in temperature—it averages about 62 degrees year-round below 20 feet in the Atlanta metro area. So when the temperature outside is 14 degrees, it’s much more efficient for your compressor to extract heat from the 62 degree ground than from the 14 degree air and vice versa in the summer when the temperature is 98 degrees.
Additionally during the summer your geothermal system gradually heats up the ground outside probably 25 degrees by the end of summer. When winter arrives you are going to begin extracting that heat that you have been storing up all summer long and again use it to help your heat pump warm your house. This process gradually cools the earth outside your home by the end of winter and the cycle repeats it’s self over and over, year after year. Think of your back yard as a giant battery that stores energy in the form of heat.
There are many other benefits to geothermal systems as they can also be used to heat the water for your home for free. The typical cost for this upgrade to a home is around $500. And because the compressor is located indoors or in some cases an outdoor enclosure, it won’t be as susceptible to exposure damage such as grass clippings, mold, dust, rain, snow, bees nest, & other animals as conventional central air units, which need to be replaced every 11.7 years according to the ARI (air-conditioning & refrigeration institute) mostly impart to the exposure damage they obtain. Geothermal units are rated at 20 years according to the ARI. Technically they cost 2x more but they last 2x longer and can cut your power and gas usage by 50%. Additionally they are quieter and have a residual value to the home when you are looking to resale.
The technology works best in areas with pronounced seasonal high and low temperatures and good soil for heat transfer. In most cases you can actually save money by installing a geothermal system as well. An example of this is: Additional cost of a Geothermal system = $120 per month. Power and Gas bill savings of a geothermal system = $130 per month. You are actually saving $10 per month by using this system. Additionally you must look to the future when there are possibly rate increases in gas and power. Who knows how much you would save at that point. If you ask me I would rather give $120 per month extra to my mortgage company and receive the tax benefits rather than pay my utility provider more money each year for the same service that just seems to have more taxes and fees applied to it.
Lets also not forget using a geothermal system is equal to planting 24 trees per year to off set your carbon footprint. With the current $2000 State, & 30% Federal, geothermal is a system that benefits you now and your children’s children in the future.
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Geothermal Tax Credits and Rebates
Invest in Geothermal Heating and Cooling Technology. The American Recovery and Reinvestment Act of 2009 has lifted the cap on Tax Credits to Qualified Geothermal Heat Pumps, previously limited to $2000. Only Geothermal HVAC Technology, Solar Panels, Wind Turbines, & Solar Water Heaters qualify for these unprecedented Tax Credits.
Homeowners around the world have learned that a Geothermal Heat Pump System is the smarter way to reduce your carbon footprint and utility bills at the same time.