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Old 07-12-2010, 01:44 PM
 
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I'm researching residential HVAC options for an older two story home with basement without anything except electric ceiling heat. I came across information on residential geothermal systems and was wondering if anyone has real-world experience to share regarding purchasing one. In particular I know a system for the house I'm looking at would run approximately $20k to install while a forced air system would cost about $12-15k (FYI there's no current ducting in the house). What is the annual/monthly savings you enjoy with your geothermal system? Are there any lessons learned to share?

Thanks in advance.
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Old 07-12-2010, 02:13 PM
 
Location: Visitation between Wal-Mart & Home Depot
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A lesson learned in attempts at geothermal cooling in Southeast Texas was that soil conditions and permeability are extremely important. Geothermal is largely ineffective here due to silty, shaley, low-perm zones at the depths typical for residential geothermal cooling (assuming you are talking about "vertical well" loops) because it functions as an insulator and holds heat in close contact with the ground loop rather than dissipating it over time. This creates a gradual averaging effect between the ground loop and the ground heat sink and within about five seasons the cooling ability of the geothermal system has been depleted. Then you need to either drill a new geothermal well or convert to a conventional unit.

Researching the effectiveness of geothermal in your particular area is the only way to get a good, clear picture of it's long term feasibility. My guess is that a civil engineer with land development experience in your area would either be able to give you a good answer or point you in the right direction.
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Old 07-14-2010, 10:09 AM
 
Location: Londonderry, NH
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What he said.
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Old 07-18-2010, 08:09 AM
 
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Thats interesting information. So in these regions of TX no one is doing geothermal anymore? When did they find that out and how did they figure it out?

I built a house near Omaha NE and put in geothermal. I only lived in the house for 2 years so I don't know what would have happened after 5 years or about the particulars regarding permeability - the installers never said anything anyway. I liked it, my house was entirely electric but with ducting and forced air. I liked not having a propane tank. Think it was cheaper monthly than straight electric heat pump (install was of course quite a bit more). The reason I liked it most of all....winters in NE are cold for sure and the heat split is such that supplemental electric would have to kick in at times - but I like a cool house so not as often as some people. I like a cool house in summer too and that was my favorite part - on a lot with zero trees and baking sun and hot winds - the geothermal kept the place cool without trying too hard. My monthly electric bill seemed pretty small to me. But then Omaha has a lot cheaper electric then other states I've lived in.

I'm not positive but I don't think geothermal is as practical in the extreme north or south because the steady 50 degree temp in the earth can only be 'split' a certain percentage higher or lower. That probably doesn't make much sense cuz I only understand sort of intuitively. So, as I'm sure you already know, whether the higher cost of installation be end up a savings down the road depends a lot on (1) your weather location and (2) the local cost of electric in your area.
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Old 07-18-2010, 08:55 AM
 
Location: Georgia, USA
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Quote:
Originally Posted by mbuszu View Post
I'm researching residential HVAC options for an older two story home with basement without anything except electric ceiling heat. I came across information on residential geothermal systems and was wondering if anyone has real-world experience to share regarding purchasing one. In particular I know a system for the house I'm looking at would run approximately $20k to install while a forced air system would cost about $12-15k (FYI there's no current ducting in the house). What is the annual/monthly savings you enjoy with your geothermal system? Are there any lessons learned to share?

Thanks in advance.
We are in north Georgia.

Hubby & I installed ground source heat pumps when we built our home in 1986. The home is a passive solar design. There are separate units for upstairs and downstairs. The main living area, includiing the master bedroom, is upstairs. The additional bedrooms are downstairs in what is essentially a daylight basement. Since our children are grown and no longer in the house, we can leave the downstairs unit off most of the time. The system is the original one. Apart from some refrigerant leaks and a few minor repairs, it has been trouble free. We have an excellent HVAC guy who keeps it tuned up for us.

We have been extremely happy with the system, which does use vertical loops. I cannot tell how much the saving is since we never had any other system in the home. We are comfortable in summer and winter. Our summer bills are probably higher than for the average family because hubby is extremely heat intolerant. He would leave the thermostat on 60 degrees year round if I let him. With the heat we are currently having, we just leave the shades closed all the time.

The units are installed in a room in the daylight basement. There is nothing outdoors, and they are very quiet. This also means they are not vulnerable to the copper pipe thieves who are currently a problem in our area.

If you are retrofitting an older home, you should ask the installer, whichever type of system you choose, to update insulation and weatherproofing, if needed.

We also have solar hot water, which I like.

Edited to add: your HVAC guy (or gal!) can estimate how long it will take for the more expensive system to pay for the increased installation cost. If you plan to be in the house at least that long, you will break even. If you plan to sell, it may or may not pay for itself.
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