The Low Down On Green Living
July 14th, 2008
Are Geothermal Heat Pumps For You?
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Over the past few months we’ve noticed quite a bit of interest in geothermal heating and cooling amongst our site visitors, and in particular in geothermal heat pumps. We’ve also had many questions from people about exactly what they are and how/if they should consider them as an eco-friendly heating/cooling option. If this describes you, then read on - these systems ARE incredibly promising technologies to heat and cool your home, but they’re also more complicated than your typical AC or furnace unit. We’ll try to help clear the air!
We get into quite a bit of detail below, but before you get into that here’s a very quick summary of geothermal heat pumps:
- Geothermal (or ground source) heat pumps can be incredibly efficient, delivering 3-6x as much energy for heating and cooling as you use to power the equipment;
- They are in some ways a renewable energy system, since they use the heat contained in the earth to provide heating / cooling;
- They do require extensive installation work, including excavation or drilling to install subsurface pipes; and
- They are more expensive than traditional heating/cooling equipment, but the payback period is less than five years almost everywhere in the country due to their greater efficiency.
What is a Heat Pump?
First things first, though: what exactly is a heat pump? Well, just like it sounds, a heat pump moves heat from one place to another rather than creating heat or cooling by burning a fuel (like a furnace or boiler). They do this by taking advantage of the fact that liquid refrigerants absorb huge amounts of heat when they turn into gas via evaporation, and release that same heat when they are condensed back into liquids.
The most common kind of heat pump, called an air-source heat pump, uses the energy in outdoor air to heat and cool. To cool a warm space, a heat pump evaporates the liquid refrigerant in copper coils indoors and condenses it (via a compressor) in similar coils outdoors. To heat a cold room, a valve is activated that reverses the process: the gaseous refrigerant is condensed indoors where it gives off heat, and it evaporates in the outdoor coils, picking up heat from outdoors in the process. Air conditioners and refrigerators use the same exact process to deliver their cooling performance.
Why are they such great heating and cooling options? For one, heat pumps can be incredibly efficient: because they move rather than create heat, they can often deliver 3-4x more energy into your home than you use to power the heat pump (high efficiency air conditioners have the same benefit). Unlike air conditioners, heat pumps also provide both heating and cooling, meaning you don’t need two separate systems that only get used for half the year.
With all of these benefits, you might expect to see air source heat pumps everywhere, so what’s the catch? Well, because they are more complicated than typical air conditioners and furnaces, they’re a bit more expensive up front. And, they work best in relatively moderate and humid climates: the greater the difference between the indoor and outdoor temperatures, the harder they have to work. Once outdoor temperatures drop below 40 degrees or so, heat pumps are no longer efficient as heaters and you need some kind of auxiliary heating. In very hot climates with low heating needs, air source heat pumps are no more efficient than air conditioners but are more expensive.
The Joys of Geothermal
Fortunately, there’s a great way around these limitations on traditional air source heat pumps. In even the most extreme climate regions, the temperature several feet underground is between 45 and 75 degrees Fahrenheit. Enter the geothermal heat pump (also called GeoExchange heat pumps and ground source heat pumps). These heat pumps circulate a fluid through piping buried in the ground, discharging heat to the ground in summer and pulling it from the ground in winter. The heat pump coils are in contact with this fluid rather than the outside air as in a standard heat pump, thereby avoiding the huge temperature swings of our atmosphere. Geothermal heat pumps can be incredibly efficient, delivering from 3-6x the amount of energy used to power the pump’s compressor and fans/pumps.
There are several options for installing a ground source heat pump. The choice of which one makes sense in your area involves many factors, such as how much land you have available, what the underground conditions are like, and the skill / experience of installers in your area. As you scan these options you might think “wow, these must be expensive!”, but due to the incredible energy efficiency of these systems payback periods can often be less than five years.
Installation Options
The most cost-effective option for residential applications is called closed loop horizontal installation. In this type of installation, plastic pipe is laid in horizontal trenches at least four feet deep. The pipes can be installed straight or in loops resembling a big Slinkly - this requires deeper but shorter trenches, which can help in smaller yards. For a typical home, you might have to install 1,000 - 2,000 feet of tubing/piping, so this isn’t a small project!
A second option is called the closed loop vertical system, in which u-shaped sections of pipe are installed in borings drilled 150+ feet deep. These systems are more expensive because of the drilling costs, but they can be used in tighter places or where the soil is very rocky or difficult to dig in. Vertical systems have been employed in areas as densely populated as New York City.
A final common option is referred to as an open loop system. Here the heat exchange is done via groundwater withdrawn from a well rather than through a closed loop of piping. Heat is transferred from the water to the building via the heat pump, and then the water is reinjected into the groundwater aquifer via a second well some distance away. This can be the easiest approach from a technical standpoint (and can work in dense urban areas as well), but it can introduce some permitting hassles in areas where groundwater is used for drinking or is tightly regulated.
There are some other options (such as using a lake or pond as your heat source), but the three above are the most common options in most residential situations. There are also some interesting innovations in the technology of the heat pump equipment itself (such as using the waste heat for hot water, hooking the heat pump up to in-floor radiant heating systems, and other higher-tech approaches), but we’ll cover those in a separate posting.
Geothermal Heat Pumps Near You
Clearly, finding a contractor skilled in this type of system is critical! We have a directory of geothermal heat pump installers around the country here. If you don’t find any in your area, then check out the installer lists provided by some of the top heat pump manufacturers:
Oh, one more thing to note. A geothermal heat pump is NOT the same as geothermal heating, where you heat your house directly using hot water pulled from deep underground. There aren’t that many parts of the country with the necessary underground geothermal energy to do this (primarily in the West), and even in these places almost all systems are commercial-scale operations. So if you’re thinking of harnessing the earth’s energy for your heating / cooling needs, most likely a geothermal heat pump is the way to go!
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Comments
Melissa Makris
July 16th, 2008 at 9:20 am
My husband and I bought an older home that had a 60+ year old forced air heating system with a huge oil tank!
It was very expensive to heat the house, not to mention insanely inefficient, so we looked into getting a new heating system.
After all the research, we decided that a WaterFurnace was the only way to go.
Yes, it was quite expensive to put in ($18,500 for a 1610 sq ft house), but now our monthly heating and cooing expenses are next to nothing! And it will pay for itself in about 5 years - sooner if oil prices keep soaring!
Another plus is when the system is cooling our home, it actually funnels all that hot air into our hot water heater! We have free hot water during the warmer months!
So it was really a no-brainer in our situation. We LOVE it!
Clean, quiet, efficient, economical… What more could you ask for?!
Sherman Health’s Geothermal Lake « The Future of Sherman Health
July 16th, 2008 at 10:49 am
[...] money saving technique is becoming a popular topic all over the world. An article titled Are Geothermal Heat Pumps For You? Goes into great detail and is a good resource for those who think geothermal power is just what [...]
KK123
July 17th, 2008 at 7:36 am
This is a great intro article for consumers on geothermal heating and cooling and great for those considering the technology. For a large scale, real world example of this system, be sure to visit the blog of Sherman Health, an Elgin, Illinois based hospital building a 15-acre geothermal lake.
Mark A
July 20th, 2008 at 4:34 am
This is a great idea. Such an available form of baseline energy. I’m putting together these types of tips over at the Energy Efficient Nation. http://www.energyefficientnation.org/
A primer on Geothermal Heat pumps at Low Impact Living. : Windermere - Andrew Stone
February 11th, 2009 at 10:45 am
[...] came upon this post today over at low impact living. Titled Are Geothermal Heat Pumps For You? it provides a concise primer on Geothermal Heat Pumps and is a very worthwhile read for anyone [...]
Jason Pelletier, Low Impact Living
March 4th, 2009 at 2:41 pm
In case you’re reading this after the passage of the February 2009 economic stimulus package, there are great new tax credits that can cut thousands off of the price of a new geothermal system.
All of the information is contained in this post: http://www.lowimpactliving.com/blog/2009/03/02/more-money-in-your-pocket-from-obama-stimulus-plan/.
canadiyank
March 10th, 2009 at 10:14 am
Melissa - I love that your system heats the water, wow, that makes so much sense! I will check out the WaterFurnace system, thanks.
Ray
March 10th, 2009 at 7:31 pm
I prices out a geothermal system for my house, a cape Cod on Long Island. They said it would cost 60k and wouldnt work we because my soil is like clay.
Air Conditioning guys in san Antonio
April 4th, 2009 at 3:40 pm
we are really looking into geothermal systems and price is an issue with where we are at.
Lucas
August 13th, 2009 at 12:27 pm
Great article, if anyone is interested in more info you should check this out.
Eric
August 14th, 2009 at 6:33 pm
After 7 months of research, we took the plunge and installed a geothermal ground source heat pump. What really pushed us was the 30% tax credit for geothermal systems that the US government just implemented in the latest stimulus package. The entire system cost us about 34K and after the 30% tax rebate the real cost to us was a little under 24K. With energy savings between 6 and 7K per year, we will pay for the system in four years. This is a whopping 25% return on our investment, tax free. Where can you get that in today’s market and be environmentally responsible to boot?
We opted for a horizontal slinky loop of geothermal pipe buried 6 feet under ground. We have an older home (115 years old) and we needed 8 tons of cooling and heating. We have two zones; one is a 3 ton system and the other a 5 ton unit. So far the home is quite comfortable this summer and humidity levels are averaging at 45% with indoor temperatures at 73 degrees.
George
August 24th, 2009 at 1:10 pm
Thats a great explanatiuon of how geothermal works. Thanks for sharing.
Dawn
October 13th, 2009 at 5:59 am
We have signed a proposal to go with a geothermal system, and are working on the contract now. For those of you who have had a system installed, what is your typical indoor heat in the winter when exclusively using your geothermal system for heat? The same question for summer. The contract states 68 in the winter and 72 in the summer, but they say those are conservative numbers.
Geothermal Heat Pump
March 20th, 2010 at 10:36 am
A ground source heat pump extracts ground heat in the winter (for heating) and transfers heat back into the ground in the summer (for cooling).
Lindsy
August 3rd, 2010 at 11:20 am
I love any type of geothermal but my absolute favorite is egggeothermal! if you want to see why go the there website at http://www.egggeothermal.com
Geri
August 6th, 2010 at 11:24 am
Hi
We had a geo thermal system installed late 2008. Closed loop. Our first bill was 625.00 when i told the installer that something must be wrong he said no. each month our bills got worse and each month I complained. Finally from sick and tired of being ignored by the installer I contacted Carrier Corp. Finally the manufacture and installer found the error–a faulty switch. Each time our unit turned on the auxillary unit went on too. in one year we spent over $7000.00. When I went to Carrier for some refund of the extra monies I spent, carrier told me it was the installer’s fault–a piece of insulation fell into the unit’s heating system which cause the problem of high bills. Now the installer is ignoring my calls. So we are getting an attorney.
but my real question is we have not seen any difference in our bills, sincre supposedly thre problem was fixed and was wondering why we haven’t. we live in southern NJ when I had oil and electric we spent 5900.00 per year.
Of course I paid much more since before the mistake was made but now our bills are compreable to what we were paying in 2007 with oil and electric. Shouldn’t our bills be half of that? And we were also told that our system has to work harder since they used the old ductwork in our house so this is why our bills are not less. Shouldn’t we have been told that prior to spending 30,000.00 and shoulldn’t have they installed all new duct work.
My husband and I are at our wits end with this and do not know if we should have the system take out or not. we cannot find anyone to come and tell us why our bills our so high. I have been keeping my thermastat at 74 during the day and it goes down to 73 at night we have a 2 zone unit.
Please can someone elighten us
Thanks geri
Jill Miller
October 1st, 2010 at 5:53 pm
GO GREEN! (your planet will thank you later)
you pick up your trash after an afternoon in the park,you wait till dusk to mow your yard in the summer, you bring your own bags to the grocery,you recycle for goodness sake!! so, why are you still heating and cooling your home with the precious little amounts of the earths fossil fuels??? Geothermal technology allows the temperature of the earth to heat and cool your home. With this technology you not only receive hot water(yes..completely free..!!) but, also, your heating and cooling costs will lower dramatically most times, up to 60%!!!!
call me, Jill or my husband Bobby, anytime, day or night with questions 317.345.7049…if we don’t answer right away, we’ll get right back with ya! or you can email, jillyanmiller@yahoo.com or geothermal2009@yahoo.com… we love making the earth a better place to live, one install, one customer at a time!! check out our website too if you get a minute…www.midwestgeothermalexperts.com
thanks and have a great day!!
peace,
Jill Miller
air water heat pump
October 2nd, 2010 at 5:15 am
Geothermal heat pumps have high COPs. While, air-water heat pumps are more convenient for installation.
jill mill
October 10th, 2010 at 8:27 pm
Check out our website, http://www.midwestegeothermalexperts.com -Jill and Bobby Miller, we know our stuff!
Lindsy Babe
October 14th, 2010 at 11:51 am
I love Geothermal but my absolute favorite would have to be Egg Geothermal! because they are Renewable.sustainable.comfortable!
for more information go to http://www.egggeothermal.com
imitation christian louboutin
December 9th, 2010 at 11:04 am
Analysis is right, I agree with your point of view.
source heat pumps
March 5th, 2011 at 9:03 am
Geothermal heat pumps are great for home or industries. It is designed to take advantage of the moderate temperatures in the ground to boost efficiency and reduce the operational costs of heating and cooling systems.
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