Anyone out there have input to the geothermal home heating and cooling. This would be to retro fit an existing central system. Our electric unit is almost 19 years old. No problems at the moment, but you never know...we are looking ahead to when it will need replacing and are considering this option. We are in zone 7, se Tennessee weather, so we need as much cooling as heat. Any input would be helpful. Thanks for your time!

Amy, thanks for posting at the board. I have no idea, but I guarantee, someone will be along to help you.

Hope you have the time to read some of the posts as this has been talked about before.

Search the forums.. I know that several here had mentioned theirs in the last 6 months..a couple were the water source and others were the ground source...
For water source you use a second well or pond to pull from.. the ground version uses the constant temp below the freeze line...

google it

Oklahoma State Univ.. pioneered the field...

We do hvac in TX and we've installed a couple but and serviced many... I'll be glad to get you some sites to read through if you'd like...

It's alot like using a chilled water sytem in a commercial setting... it can be costly so you want to look at your payback to make sure you'll get the most for your money...


If I remember correctly we actually had someone in the TN area that had one plus some in the NW... I'll check back..

Becky

We had that system in a log house in IN; it was very quiet/efficient.

As one of the other posters mentioned, there are two types, open system and closed system. The energy production aspect of both is similar. It is effectively a heat pump system, but instead of using the ambient outdoor air to cool/heat the circulating refrigerant, it is run by or through water. This works much better than a typical heat pump for 2 reasons:
1) Water transfers energy much more effectively than air
2) the ground (2 feet below the frost line) maintains a fairly constant temperature all year round, so the heat pump is able to draw more heat from the ground in the winter, and pass more heat out to the ground in the summer.

In an open system, water is pulled from underground (or possibly a nearby pond), used to transfer energy into or out of the heat pump, and then returned - either to the pond, or to another well, typically some distance from the well used to draw in the water. To use a well-based open system, you will need a fast-filling well - at least 5 Gallons Per minute. Some soil types are not well suited for the return aspect as they cannot absorb the returning water.
A closed system uses the same water continuously, through a series of pipes run underground. They can go vertically into a deep (15 feet or more) trench, or more typically, horizontally under a lawn below the frost line - however you have to have a pretty big yard - to acheive real efficiency you need a lot of underground pipe and each loop (like underfloor hydronic heating) has to be a certain distance apart.

At a basic level - open systems will require more electricity to run pumps - either from from a pond or a well. Closed systems don't take as much pump power because the returning water balances out the gravity aspect of moving it below and above the ground level.
Open systems are also much harder to get approved by zoning and land use boards. Drawing and returning water can potentially impact the water table for your neighbors, and if you use a pond, the return water (especially in the summer) will be hotter than what you took out, raising the pond's temperature and potentially affecting plant and fish life.

A closed system requires lots and lots of land. You may not be allowed to use land that has a septic field on it either - some communities dis-allow that. You can't run through the woods, the depth needed will disturb too many roots. There is also the cost of actually digging trenches to lay the loops, and landscaping afterwards.

Still, if you have the space and are not overly restriced by your community building restrictions, it's much, much more efficient than regular heat pumps, and depending on your electricity and fossil fuel rates, can be cost less than half as much to run than a comparable oil or gas system.

We replaced our old unit with a geothermal about 8 yrs ago. I'm not real familiar with how it operates(that's hubby's area),but I do know our electric bill went way down. It is fairly expensive to install, but it pays for itself. We only have an half acre lot and it is a closed system. We love it!

Hi Amy, Here are two links you might also find helpful. Good Luck

http://www.eere.energy.gov/consumer/your_home/space_hea...ex.cfm/mytopic=12670

Geothermal video

I have one. Mine is open loop, but both legs of the loop are wells that reach the ground water, so I'm not depleating the groundwater and I'm not heating the creek out back. Rob Camp is right - the expensive, difficult part is drilling the wells for the open loop or tearing up your yard for the closed loop.

I love my system. I have the lowest electric bills in the neighborhood, and electricity is the only utility to my house. (My drinking water comes from the same well that supplies my heat.)

Thank you EVERYONE for the great input. Looks like something to do lots of research about. Probably would make more sense to replace a non-working or worn out system with this type system. We're not to that point yet...but like NEEDING a refridgerater quick when yours goes...good to have an idea of what your going to do if and when. I'll be checking out all the links and do lots of googling. You all are the BEST!

Amy, This link gives you info. about the Tn. Incentives for Renewables and Efficiency. Find your light company and see what they might be offering. Some of them offer loans for the geothermal heat pumps. From what I've read they are good to have. Good luck.



Tn.Incentives for Renewaable&Efficiency

We have a closed loop system that has been operational for over 8 years. We like it and believe that our electricity bills are lower but find it difficult to compare because we have a different provider than in our previous home. We have recently replaced the third of four pumps that circulate the water from the loops. Choose your contractor wisely. Apparently we did not and the company that offered this tremendous warranty and many promises went out of business about a year and a half after our installation. We have only been able to find one company in the region to service our unit. This company also does installations and we would seriously consider having them do another system for us should we build again. (I love having no noisy unit sitting outside the house.)

Thank you for the info! Checking out and choosing the contractor will be key.