Anybody have geothermal heat/AC?

ginam_ohJune 29, 2005

We're considering it and I know it's expensive, but I'm definitely curious enough to ask around and talk to people who have it.

Anybody here have geothermal? Love it? Hate it? Would you recommend it?



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Well, since you haven't gotten any responses in a couple of days I thought I'd throw my two cents in. I considered geothermal at one point, and it doesn't have to be expensive!

From what I read up and studied up on it would have probably worked where I lived in NC at the time. You just dig down a few feet, run pipes for the air to circulate through, and re-circ it into the house.

I was leery about the 'couple of feet', but I do know that the ground where we were (and most places) "more" than a couple of feet down will stay around 55F.

If you're in Ohio, you'll have to get down below the frost line to take advantage of the heat. It would not be a substitute for your main heat system, just an assist to get the temp up so your elec/gas/whatever system wouldn't have to work so hard. On the other side, the 55F air getting pumped in during the summer will definitely help your AC system, if you even have one there.

I think it really could work. As I sit here in the basement level of a house in NJ, topside temp is 73F, dog's water bowl (sitting in basement floor all day) is 62F. It's really feeling cool down here, and stays this way all summer. In the winter, nothing ever froze in the basement, but pipes did burst upstairs (this house has been in the family 60 years, so I know).

The main thing to remember is that geothermal is just an assist to your main source of heat/ac.

From one Gina to another: Good luck!

    Bookmark   July 3, 2005 at 12:22AM
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I don't know if anyone is hanging around this thread, its been a while since the last post, but I thought I would write anyway since I'm bored right now and this is an interesting subject. GinaM, just like with solar heating systems, there are two types of geothermal (GT) systems "passive" and "active." When talking about the temperature in her basement being cooler in the summer and warmer in the winter, Gina_in_Fl is obviously referring to simple passive GT. In the summer when air temperatures are high, the walls of her basement, being built into the 55 degree soil, absorbs the heat and transfers it to the cooler ground, thereby cooling the basement. In the winter, the system works the other way, and the walls maintain a temperature near 55 degrees which helps warm the basement air.

I have an active system in my house, utilizing a heat pump that is assisted by a GT "loop." The system involves two "well" holes drilled down to access the water table (25 feet at my place). The water does not need to be "good" potable water because you are not going to actually use the water, all you are interested in is the GT heat held by the water. The drillers (using very fancy drilling equipment) then ran a shaft horizontally between the two vertical shafts to connect them. The vertical well shafts are about 20 feet apart. A series of coiled tubing was installed in the horizontal shaft and lays in the groundwater, which at my location is a constant 54 degrees. The system pumps water (isolated from the groundwater) down one side of the GT coil and back up the other side to the heat pump heat-exchanger. In the winter, it pulls heat out of that 54 degree water to warm the air that it blows into my house. In the summer, it pumps heat from the air in my house, transferring it into the 54 degree water which is then pumped back into the ground.

Gina_in_FL stated, "it would not be a substitute for your main heat system" but in fact the GT system is the only "real" heating system, and the only cooling system I have and it maintains a comfortable temperature year-round in my well insulated, 2,100 square foot one-story with basement house, year-round. We do have a fireplace, but we use it infrequently (I think 8-10 times last winter) and only for ambience on a cold winter night, never for the heat. Being in Ohio, such a system would work well for you, because your temperatures cannot be more extreme than ours here in Nebraska. Our summer temps are usually in the 90s (last Saturday and Sunday it was 104) and winters with periods of very cold temps as low as 10-below are not uncommon.

The system installation for what I have was rather expensive I suppose, about $9,000 in all (in 1998) but some of it was tax deductible under the "renewable energy" provisions, and my heating bills in the coldest winter months average around $110 and cooling costs for July August are typically around $135. The highest winter bill in the last 7 years since installation was $132 the month my mother-in-law was staying with us and she kept the thermostat set at 80 (That month I spent a lot of time in my workshop out or the "heat"... and away from the too-warm house temps). These costs are far below what my neighbors are complaining about paying for their conventional H/C systems. As energy costs continue to rise, my realtive savings will likely increase.

As Gina_in_FL suggested, there have been attempts to simply use tubes buried in the ground, through which air is blown to cool or warm a house. Some people call these "semi-active" systems because there is some mechanical (active) means of moving air through the system, but the cooling of the air is simply conduction, like in a fully passive system. I have known a number of people who attempted this method without success. One trial I am familiar with (in Arkansas) used more than 1,000 feet of 6-inch thin-wall PVC pipe buried 4 feet below the surface. The pipe was divided into 4 loops, so air from the house was blown through roughly 250 feet of pipe and returned to the house. However, it was found that the volume of air needed to affect the temperature of the house is too high, and the amount of heat transferred into the ground from the air blown through the tubes is too low to be of much use. An added problem was condensation in the piping. As the warm-moist air moved through the pipes and gave off what heat it did, it also left moisture behind. The moisture in the pipes then became stale (not to mention the mold and other allergens) and the air coming out of the pipes became very unpleasant (much like a basement that never gets fresh air).

    Bookmark   July 27, 2005 at 4:49PM
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Read Hairy-old-mans reply on geothermal. Where can I get info on the system you installed. It sounds great and not near as expensive as others I've investigated. My email is just in case I can't find it here. I haven't used this site before. Thanks, Mike from NJ.

    Bookmark   March 22, 2007 at 7:46PM
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I spec'd out a house last year that the homeowner wanted geo thermal installed in, so I learned a lot, but hairy guy's post still made my eyes glaze over :)

Call your local plumbing/heating association or union and ask for some contractors who specialize in geo-thermal, you should probably find some. Or even do a search on the web and go from there. Geo-thermal is pretty specialized and the contractors that do it usually have a relationship with a team of subs and suppliers, from the well diggers to the plumbers and HVAC guys doing the final installs.

You will need a pretty heavy duty backup generator to ensure that everything keeps humming along in the case of loss of power. Also, you need to ensure that you have enough water flow from your existing well/water service, or you may need to dig another well. Also, you may have to check with your muncipality if you get municipal water as around here, some localities are behind the eight ball and view geo-thermal with suspicion and worry about the water draw.

Also, you have to take it easy with fancy plumbing (i.e., multi-head showers), as you have to consider carefully the total water draw as your heating system is always going to be the primary draw on your water supply.

    Bookmark   March 25, 2007 at 1:36AM
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I installed geothermal in an 1898 house in Montreal two winters ago. It was not too expensive as the system also provides air conditioning (which we didn't have previously) and the old oil furnace/tank needed to be replaced anyway. The only extra cost was drilling the vertical loop - but we're saving so much money on heating (and now have the added benefit of cooling) that break-even time is about 4 years at the current price of oil.

Here's a picture of the drilling of the vertical loop:

This is a 2000 square foot house and the annual energy bill is now around Can$1300 in a climate that has around 9000 heating degree days per year.

Paul in Montreal

    Bookmark   March 28, 2007 at 6:27PM
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hi, we have a family with a geo thermal home in a town down the road from us, there house is probably 5000sq ft, and his bill is 130.00/month. he loves it, the community that i live in is redoing our hockey arena and we are using geo thermal so that we can have artificial ice, even in the dead of summer if we want it!! it dosnt cost all that much to put in and the monthly cost of running it is about 1/3 of using freon (which is now almost illigal to put in as it is hard on the enviroment). good luck great pic paul in montreal!

    Bookmark   March 29, 2007 at 12:34PM
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We built our house last year and installed the cousin to geo-theraml, called "air source" heat/AC.

Geothermal obtains its heat transfer from the ground, whereas air-source gets its heat transfer guessed it...the air. Air-source installs are cheaper than ground-source since there's no drilling and no running of extra pipe. This "Lennox" cost about $15,000 CDN ($13,000 USD) Just a simple unit that sits outside the home that looks like a typical AC unit. It will draw heat from the air until the outdoor temp drops below -20 degrees Celcius (-4 F). Only then, does the elctric heat kick in.

We have a 3000 sq ft home and from March 206 to March 2007 our total electric bill was $1500 CDN ($1300 USD). Two people in the home, constant indoor temp of about 21 to 22 C (70F), includes AC in the summer when temps reached 35C (95F), and when didn't make use of a colthes dryer. Opting to hangs clothes on the line outdoors in the summers, indoors int eh basement during the winter.

That's about all the variables I can think of.


Here is a link that might be useful: our house building process

    Bookmark   March 29, 2007 at 8:40PM
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