Results 1 to 7 of 7
  1. #1

    Sizing the ground loop (Ground loop oversized??!)

    Hey guys, I've visiting this site for a while now learning all about ground source heat pumps and would really like to use one on our new home we are building. I've had a manual J and D completed, and now the ground loop design in coming back and I just don't understand how these folks are coming up with their numbers. Here are the details:

    House size: ~5170 sqft. (I know this really doesn't matter, but thought you would like to know)
    Location: Mountain area just East of Albuquerque NM (Very similar to Santa Fe, NM)
    Elevation: 6890'
    Ground temp: 66-68 (according to all the charts that I have seen)
    Ground material: Limestone (we had a soils report done)
    Heat loss: 90,510 Btu/h

    Loop design will be vertical, we have 2 acres, but there is limestone just under the surface and trenching would be difficult.

    Some folks (I don't know who came up with these numbers exactly) believe we need the following:

    Bore holes: 9
    Depth: 300'
    Pipe size: not listed

    What do you guys think? I know some of you have access to the computer software that can size these loops, would you care to run my numbers? I think that the size should be more like 8 bore holes at 250' each, and that may be over doing it still.

    Please help, over sizing this loop will put this system out of reach financially!!

  2. #2
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,378
    90,000 BTU heat loss is quite high for a brand new home. Perhaps put more money into sealing the house and downsize the geo system. Weigh the cost of using backup heat on those super cold days vs. the cost of the larger loop. You may find payback time for the larger loop isn't worth the cost of of installing it. If your heat loss is 60,000BTU or less on all but 1 month of the year, is it worth installing 50% more loop to save from using backup heat to make up the 30,000BTU differnce for that month?

  3. #3
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    2,001
    What is your cooling load? Cooling load can be very important in determining loop size even in heating dominant climates. I did some VERY rough calculations and came up with 2,500 feet or boring assuming a 80K cooling load and two 4 ton systems through average rock with .75" piping(keep in mind i have no knowledge of your area and do not know limestone since we have none in my area)
    I think 9 bore holes at 300' is probably correct and that 8 at 250' will be to short but I would need the cooling load to get a better calculation.
    Check out my YouTube channel - http://www.youtube.com/user/skyheating1 We have customer testimonials, product reviews and more!
    Like us on FACEBOOK if you like our advice here!

  4. #4
    What about going with an open loop well? As Skyheating said I dont know your area, I just know that here in Ga I have installed a few of these and they have worked great, it also eliminates the need for multiple holes. Again I know NM is a lot drier than normal, but is it not possible to tap into the aquifer at all?

  5. #5
    Join Date
    Dec 2008
    Location
    South Jordan Utah
    Posts
    158
    the OP has moved on with his install. This thread is dead.
    Dewayne Dean

    www.palacegeothermal.com

    See my live system data here:

    We Heat and Cool with Dirt

  6. #6
    Join Date
    Jan 2010
    Posts
    6,381
    Quote Originally Posted by geodean View Post
    the OP has moved on with his install. This thread is dead.
    So what was his final choice ?

  7. #7
    Join Date
    Dec 2008
    Location
    South Jordan Utah
    Posts
    158
    Dewayne Dean

    www.palacegeothermal.com

    See my live system data here:

    We Heat and Cool with Dirt

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event