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  1. #1

    Geothermal short-cycling frustration

    We have an eight year old geothermal open loop system in a 90 year old house. A newer bigger (3/4Hp) submersible pump was installed before we put the geothermal in. We have short-cycling issues basically whenever the water is running. We have replaced two bladders to no avail and a pressure switch. The current recommendation to fix our short-cycling problem is to install at constant pressure pump for $. I read varying opinions here and don't fully understand some of what I am reading.

    Could short cycling be caused by a clogged heat exchange? I would appreciate any suggestions from knowledgeable people on the constant pressure pump solution, since the attempts so far with the bladder and the switch have not helped.

    Thank you!
    Last edited by beenthere; 09-01-2013 at 08:12 AM. Reason: price

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,774
    Moved to geothermal forum.
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    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Sep 2010
    Location
    LA
    Posts
    198
    So you've had this problem for 8 yrs right? What were the reasons given for bladders and switch being replaced?
    As a blind man speaking to this problem (pun intended for lack of info) I can't see how a geo unit not giving any problems could have a restricted condenser. Has anyone increased the cut in/ cut out differential of the press switch? What size is your geo unit and your water storage tank?

  4. #4
    Join Date
    Jan 2006
    Location
    Harrisburg PA
    Posts
    18
    Cheaper route would be a mechanical cycle stop valve...beenn using them for years, and have one on my own geo

  5. #5
    Join Date
    Mar 2012
    Location
    West Berlin, NJ
    Posts
    59
    The cycle stop valve is a cheap way to stop the pump from short cycling while using water.
    The best solution we have done is installing a Grundfos constant pressure system to all our open loop geothermal installs.
    I have had success with Danfoss "Cycle Gard" valves for retrofitting with newly installed submersible pumps, but always recommend Grundfos systems.
    Dan Callahan
    www.CallahanWellDrilling.com
    Get "well educated" with us!

  6. #6
    Join Date
    Oct 2005
    Location
    Pacific Northwest
    Posts
    2,261
    I'll bet 5 bucks that there is far to much water passing through the geo's heat exchanger. Post pics of the water piping that feeds the unit.

  7. #7
    Join Date
    Jan 2006
    Location
    Harrisburg PA
    Posts
    18
    Grundfos constant pressure systems are the best...hands down. The only issue is money. They work in harmony with the geo and the house without losing any pressure, just make sure the person sizing it knows what he is doing. Seen to many oversized CP pumps....

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