My geothermal system

Discussion in 'General Discussions' started by ampicoj, Jan 12, 2011.

  1. ampicoj

    ampicoj New Member

    My new - Spring 2010 - geothermal system is made by Climatemaster/Carrier/Bryant. (Amusingly, there are three labels for the installer to slap on the equipment...). My 3800 sq ft house, built in 1993, previously had a Carrier geo system.

    [Political comment: I grew up near Syracuse, Carrier's "home". Given what they've done to Syracuse with their off-shoring, I would have preferred zero Carrier equipment in my home. I went with my dealer's wishes, reluctantly].

    There is a five ton integrated unit for the first floor. The 2nd floor is split with the
    three ton compressor in the basement and a Carrier Infinity airhandler in the attic.

    There are three wells, each of 479'. The loops are 1.25" tubing; each loop is 442'. The three loops are connected in a reverse flow setup. I think the interior piping is 2", all well-insulated.

    Flow is 15 g/minute to the five ton unit. 9 g/minute to the three ton unit.

    My base ground temperature seems to be around 54 degrees.

    During the summer the system was outstanding in AC mode. Loop stayed in the low 60s, once venturing up to 70. It seemed to recover to 54 in a day or two. We kept the house at 77 during some blistering hot weather.

    Rough cost was about $80/month. I have Energy Detective monitoring points on the integrated unit, the 2nd floor compressor and the 2nd floor airhandler. Exact costs are tricky as we are billed every two months and the rates/adjustment/fees seem to vary all over the place. We also have time-of-use metering. The Energy Detective software does account for this, but not for the various add-ons.

    Heating mode has not been as impressive. $130 to $150/month. I still have some tinkering to do: I have propane backup, via a hydro-coil in the first floor plenum. This will come on when the 2nd stage of the compressor kicks in. The loop quickly drops to 48-50. Very slow to recover it seems. It has gotten as low as 38. I don't yet have enough good data for a loop temp vs electricity cost graph. But that will come.

    One extraordinary fact: the ECM motors are wonderful! Lots of air movement and they use virtually no electricity. Truly impressive.

    Further down the road I have a water/water exchanged on the input side of the five ton unit. This will be used to warm the incoming water "somewhat" when in heating mode. This hot water source is essentially free - but not hot enough to heat the house with.

    I'd welcome comments, questions, suggestions!
  2. Fred2010

    Fred2010 New Member

    Knowing we will use more Energy to heat vs cool in the Northern areas, I think 130-150 per month during the winter we are having is reasonable. I heat a 3600 (set and forget 69F) sq foot home with a 3 T system and I am running 120-140 bucks per month. Last winter I had a few days when the system did not turn off once. it is a W-W system and my resistance back-up did not kick in. I do pre-heat my domestic hotwater from well temp to 120F

    just my 2 cents:cool: love heating with what is stored beneath me. FYI my loop is running 36F in and 29F back. 2 x 255 ' wells drilled into the granite

  3. dgbair

    dgbair Just a hobby Forum Leader

    Why do you have the propane heating kicking in on 2nd stage? I would think it would be set up to only kick in on the 3rd stage.

    Is the $130-$150 including the cost of the propane?
  4. geome

    geome Member Forum Leader

    Does the $130-$150/month include your propane cost for aux heat? Is it a common setup to have the propane hydro-coil backup engage with second stage?

    I would think using the propane hydro-coil as a third stage (in combination with the second stage compressor) would be more efficient since it would allow the more efficient geothermal system to run in second stage longer and possibly satisfy the demand without using any propane. We do not have this kind of aux, so I am not sure what would work best for your system.
  5. moondawg

    moondawg Member

    Loop temp of 38? In Syracuse in January?

    Sounds like it's working great.

    I agree on getting the propane to come on during 3rd stage instead of second.

    You've got a lot more room to move on your loop temps (more heat to be extracted) and it will be much cheaper to run your geo on a lower loop temp than it would to extract that heat from propane.

    This assumes, of course, that the loops have proper freeze protection inside.
  6. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    $130-$150 per month to heat a 3800 SF home in Syracuse? What's not to like?

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