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OT : Geothermal heat pumps. Are they worth it?

Discussion in 'Off Topic Threads' started by andybull, Feb 26, 2010.

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  1. andybull

    andybull Active Member

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    I own a home in Carolina, which I plan to someday make it my primary residence. The power bills I get for the home when I have been there for less than two weeks in one month, have been over $500.00, both in the summer and winter. The AC unit was built in '89 (I was told it's a good unit by an AC professional), it works in conjunction with an oil burning furnace.

    The main floor is around 4,000 square feet, with a basement/garage of the same square footage. I plan to have foam insulation sprayed on the floor joists (garage ceiling), also on the upstairs attic.

    I received an electric cooperative periodical with an article regarding geothermal heat pumps and it sounds like I might be able to lower my power bills if I have one installed. I have plenty of land where a well can be dug and lines can be put underground.

    Is this a good system? If so, who makes the very best?

    Thanks,

    Andy
     
  2. Setterman

    Setterman Well-Known Member

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    Andy, I built a new 3,400 sf home 4 years ago and debated on a Geothermal system in lieu of the standard LP gas furnace and electric AC unit. The Geothermal system was $14,000 more than the conventional system. I am a commercial building contractor, and very familiar with Geo systems. I had one of my Mechanical contractors do an energy audit on my house. We determined it would take 10 years to pay back the $14,000 unless energy costs increased 35%, then it would take 6 years.

    I have maximized insulation in my house,(R40 in the walls) which is different than your situation. I can heat my house with 1,000 gallons of LP/year, but you may see a better gain because of your AC costs.

    I would hire some one to do a energy analysis on your house. Based on last years useage it should be easy.
     
  3. Doug Brown

    Doug Brown Well-Known Member

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    In a house that size geothermal is a good option. I'd get rid of that oil burner, they're a pain.
     
  4. HSLDS

    HSLDS Well-Known Member

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    Over simplified, a "heat pump" (air based) needs a back-up unit for heat in most climates. The units work on a temperature differential and when it gets too cold (or technically too hot) the unis cannot do their jobs.

    Given the ground temperature hovers in the low to mid 50's a geothermal based unit is perfect. Figure temperatures in summer in the 90's (40 degree difference) and winter hitting the 20's at night (30 degree difference). This allows the extraction of heat rather efficiently.

    You most likely will NOT need a back-up unit with geothermal.

    Insulation matters too - I just saw a house approaching 10,000 sqft with an estimated cooling and heating bill of under $500 per year for a geothermal unit.
     
  5. Catpower

    Catpower Molon Labe TS Supporters

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    Are they worth it? Depends on which end of the stick you are. I've been in the HVAC business for 35 yrs and have done geo since the late 70's

    They will save energy, but most of the claims you will hear are pure BS, or they have the cheapest electricity in the world, and also keep it 55 degrees in the house during the winter, and 90 during the summer

    About the only way that geo will make a decent payback, is if you have a deep pond or lake and you can pump & dump, or install the loop in it. Boring a loop is extremely high priced, although it has come down with horizontal boring, but you still have the problem of leaks in the loop, and they do occur.

    I like geo because they are high priced to buy and with age maintain. Do we have one? Nope, but we are building one to use as we have a 7 acre lake behind our house, and it's been slow so the labor is cheap.

    But if you are inclined to get one Climate Master makes a good unit but that's what I sell. Water Furnace also makes a good unit
     
  6. trapwife

    trapwife Well-Known Member

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    We built a 4,000 sq ft home in 1996 and installed a Water Furnace geothermal unit. We also had them use the spray on insulation that is recommended to be used in combination with the geo unit. We got a rebate from our local electric coop plus a free hot water heater since our home is all electric. At our electric coop, the electricity used for the geo furnace is billed separately from the rest of the house, at half the regular rate. At first we were worried that it wouldn't be hot/cold enough, but that never happened. We are very happy with ours. It was priced higher to buy in the beginning, but natural gas wasn't available to us and I didn't want an LP tank in the yard.
     
  7. GD1949

    GD1949 TS Member

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    I installed a 3.5 direct exchange geothermal system in 20O6 and am very happy with it. It provides efficient operation for my radiant heat system and my AC in the cooling season. I used vertical boreholes ( seven 6" holes from a central axis at an angle of 70degrees) This allows a very compact footprint of about 6' diameter for the earth taps. Copper lines were installed in the boreholes and R22 flows through them in the same manner it would in a heat pump system. Only difference is the compressor unit is inside and the source of latent heat is the earth. I hope this is helpful feel free to contact me if you need further info

    George DeGennaro
     
  8. andybull

    andybull Active Member

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    George:

    How many square square feet of home did you have this done to? Being that you recently had this work done, what was the cost? Was this new construction, or old?

    I'm considering doing this for the main floor as I stated above and leaving the upstairs heating and AC unit alone.
     
  9. DTrykow

    DTrykow Active Member

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    I built a new home last year and looked in to Geothermal. With average ground temp at mid 40's it was not worth it for me. Also the cost was a 30K difference between propane and Geo. I needed a super tight house and two heat pumps and two wells. I went with propane and wood heat. Dave T.
     
  10. kehrby

    kehrby Active Member

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    Location:
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    We installed a Waterfurnace system 15 yrs ago in our 2300 sq. ft house. Our home is also full electric as getting gas run here was going to be expensive. I also heat a well insulated workshop, separate from the house, with baseboards and my electric bill is $250/month year round. Northern Indiana climate so it gets cold in the winter and hot and sticky in the summmer. I've been very happy and have had no issues other than regular maint. $8500 installed 15 yrs ago.

    Steve
     
  11. GD1949

    GD1949 TS Member

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    Ours was an addition to an existing house with a total of 4000SF. The addition was well insulated with blown in fiberglass (looked at iscynene and winced at the cost and used Spyder from Owens Corning instead) The old House was built in 1984 and had adequate insulation. I used a product called Warmboard for the subfloor in the addition. Expense was considerable; 10K for the Geo mechanical equipment and installation of the earth taps. I also used a high efficiency European gas boiler for backup to the geo and domestic hot water We have no plans to ever leave our home so we have a long time horizon for the payback. Direct exchange is definitely state of the art for this type of system. Ours was made by small outfit in PA called Greatair. Due to limited after sale support I would not recommend them although the mechanical equipment has been good so far. Hope this is helpful.

    George DeGennaro
     
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