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Geothermal A/C and Heat

Discussion in 'Energy, Environment, and Policy' started by W.Petefish, Nov 18, 2011.

  1. W.Petefish

    W.Petefish Active Member

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    Has anyone had a geothermal system put in to their house to cool or heat it? If so, How big? How much energy do you save over what you had?
     
  2. donauker

    donauker Member

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    #2 donauker, Nov 18, 2011
    Last edited: Nov 18, 2011
    I installed a two-stage 4 ton geothermal system about 6 years ago. I don't plan on ever owning a home without it.

    Here in PA our heating requirements are greater then our cooling requirements so that dictates system size. I switched from natural gas heat which was considered low cost heat. My annual savings in heating and cooling was around $1000. Of course that was when I was buying my electric. With my 16.2 kW solar installation I no longer need to buy my power.
     
  3. AnOutsider

    AnOutsider S532 # XS27

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    Our builder has one specced into our home, but as ground-breaking is a good 3-4 months away, I don't know the details. It's a "green" builder though, and he said that it's definitely worth it, though he wouldn't recommend any bigger panels unless there are state incentives (which we no longer have)

    *edit* don, I see you're also in PA. Did you install your kit before the state incentives ran out? Do you feel you'll recoup even after rebates?
     
  4. EV_de

    EV_de Model SP10/XP9 EU ZOE#47

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  5. clea

    clea Member

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    They are drilling the holes for my two-stage 4 ton system as i write this. Being as we have extreme differences in temperature between summer and winter i am hoping to make decent gains for both heating and cooling. I will be able to give a decent evaluation in a year as hydro quebec keeps good stats on the power usage for a few years and i will be able to do a comparison against my previous usage then. i have also had them include the preheat option for the hot water as well so am counting on this to make an even bigger difference being as i have 3 adolescents that like to take long showers.
     
  6. W.Petefish

    W.Petefish Active Member

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    We are doing the consult as I write this. Any problems with the HOAs?
     
  7. clea

    clea Member

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    doesn't really apply to my case. in fact both levels of government (provincial and federal) encourage homeowners to make this kind of update to their systems when applicable by offering rebates, so it becomes even more cost effective and shortens the payback period.
     
  8. W.Petefish

    W.Petefish Active Member

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    #8 W.Petefish, Nov 18, 2011
    Last edited: Nov 18, 2011
    Seems like 4 ton systems are popular with builders and installers. As it turns out, our yard is the perfect size for a 4 ton system.

    We worked it out to be a Bosch split unit with an American Standard furnace for heating. A 3 zone controller is also going to be installed.

    The only problem we are having is we haven't heard from the Home Owner's Association on wether they will object to the 4 holes being drilled.
     
  9. mpt

    mpt Electrics are back

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    Don, any recommendations on installers?
     
  10. donauker

    donauker Member

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    I assume you are referring to the state grants on the solar. I don't recall anything on state grant for geothermal at the time of my install although there was some federal tax credit I believe.

    I did get the full grant for part of the first phase of my solar install. The grant was limited to a max of 10 kW so I received that max toward my 13.5 kW initial install. The unexpected down side on the state grant was that it was federally taxable income in the year it was received, so all told the grant didn't make up for the drop in cost of materials in the time since that install. I added another 2.7 kW last year to reach 100% with our increase of electric vehicle use. This addition didn't qualify for grant since I had already received my max allowance.

    The big factor effecting payback at this time is the collapse of SREC values in our state. My initial calculations of a 7 year payback have now extended considerably but that changes based on what happens with SREC values. At this point I am not overly concerned about payback since the install is done and as the CC commercials stated some things are priceless! No gas station stops and no ongoing electric rate increases for me!
     
  11. donauker

    donauker Member

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    We do have a HOA that has fairly strict rules (zero tolerance of sheds, all landscaping change requires approval). I don't know if I even checked with them as I was new to HOA at that time and I didn't see were it applied in that it only temporarily impacted my own land and when they were done there was no visible change other then a reseeded area of the lawn and the removal of a noisy outside AC unit from the back of my house.

    I was a bit concerned about my roof mounted solar install being the first in the development but I think they got the idea pretty quick that they didn't want to do public battle on that front!
     
  12. donauker

    donauker Member

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    I ended up contracting with a well respected driller in the area for the wells and ground loop portion and with a local family owned HVAC company for the geothermal unit installation.

    I have sufficient construction and HVAC experience with years of rental property purchase and remodeling and a commercial account at a wholesale HVAC distributor so I was considering doing the purchase and install myself with a bit of assistance with final charge and testing from a the brother in law of a close friend who is an installer. But when I got quotes from several local firms who were aware they were biding against each other, I decided it wasn't worth my while doing all that work myself.
     
  13. Alfred

    Alfred Member

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    #13 Alfred, Nov 19, 2011
    Last edited: Nov 19, 2011
    I have 2 vertical bore holes, 300m deep each. They feed the "heat source" side of two Vaillant heat pumps. The base of the calculation for this type of installation in Switzerland is to assume about 50W per m of heat exchange tubing underground. So if you need 30kW peak, you will install 600m of tubing to exchange heat. Vertical bore holes are nowadays the most common type of installation. Horizontal registers cool down your garden and not everybody has enough room. The costs of operation (electricity) are about 3-4 times lower than what I paid or might pay now for gas. Linear payback will depend on oil price (gas is tied to that) and will be about 5-10 years. Tax concessions and support from the local electricity board assisted. Heat pumps of this type are by now very common in Switzerland. I heard that they command currently a dominant share of new installations. To cool your house as well would be possible, but is not common. We do not have more than a few weeks with 30°C (86°F) or more each year and that you can survive without cooling.

    How those bores were put down I summarized in a short film here: MobileMe Gallery
     
  14. Eberhard

    Eberhard #421 Model S #S32

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    300m is really very deep. you should also see an increase in temperature of 3° each 100m. 15°-20°C that what you can expected. Very nice for a heating pump. in germany the maximum is 100m because of "bergrecht". If you go deeper here, you need an exploration permission.
     
  15. W.Petefish

    W.Petefish Active Member

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    We are having 4 300-400ft (91-122m) holes bored in our back yard and from what the geothermal map looks like it will be a good amount of heat flow.
     
  16. Alfred

    Alfred Member

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    We also need permission. How deep I was allowed to go was decided principally on the basis of geological information. I am sitting on a block of sweetwater sediments starting about 200m above nearby lake levels. So I was given a more generous allowance than someone lower down would have received. This was very fortunate as it is cheaper to drill just two holes for the 600m of total length sought than to drill a larger number of shallower holes. Fewer holes mean also fewer connections and pressure balancing devices on top.The effect you mention due to the thermal gradient helps of course too. So far my source never averaged less than 9°C. Now it runs around 12°C at the beginning of the season.
    I just saw an estimate that about 80% of new homes here are heated by heat pumps and that about half of them will take the heat from the ground (the remainder being air probably).
     
  17. W.Petefish

    W.Petefish Active Member

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    Got finished with the drilling today. (they drilled 4 holes 91m deep in a day) Facebook photos. I got numerous comments and questions when I rolled up in the roadster.

    No complaints from the HOA yet.
     
  18. shark2k

    shark2k Member

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    Any more updates on this? Always like reading/seeing stuff of about ground source heat pumps.

    -Shark2k
     
  19. clea

    clea Member

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    my system is ready to go online tomorrow. After a few delays with the drilling all the issues have been resolved and they are just testing the pressure in the lines overnight before they make the final connections and flip the switches.
    downloaded all the usage data from hydro quebec for the last three years and will use it as a basis for comparison against the newer data to see if my analysis of an eight year payback period is reasonable.
    don't know if anyone else has set theirs up but i added the connection to the hot water tank as well to preheat the water in a tank which is the feeder for the main hot water tank. am curious to see if that also affects it. not sure if i will be able to differentiate its effect from the rest of the system however.
     
  20. VolkerP

    VolkerP EU Model S P-37

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    clea,


    thanks a lot for putting up that information.
    Is your system capable to put excess heat from solar thermal (or any other heat source) back into the ground? If not, was that a consideration and you decided against it?
     

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