Hard Water in Closed Ground Loop

Discussion in 'General Discussions' started by Doug Stansbury, Mar 4, 2021.

  1. Doug Stansbury

    Doug Stansbury New Member

    I have a closed loop GSHP that was installed in 2014 and have become concerned recently that the water used to mix with glycol and fill the ground loop, may have been taken directly from our well instead of using distilled water as quoted at the time of installation. The water in the ground loop has been tested recently and my suspicion has been confirmed. The water was found to be very hard at 384 mg/L CaCO3. I am concerned about scaling in the heat exchanger and reduced efficiency and/or damage to the system. I am curious to hear if others have had this issue and what the recommendations are to address this concern. Thank you.
  2. SShaw

    SShaw Active Member Forum Leader

    Manufacturers typically publish water quality requirements in their installation manual. Look up the specs for your unit.

    Below are the specs from Waterfurnace. PPM is the same as mg/L, so your well water is slightly over their specs. Note that this is more of an issue with open-loop systems that are constantly bringing in new water. Since you have a closed loop, it's a self-limiting issue. If any scaling did occur, that would remove the minerals from the water and the hardness level of the water in the loop would go down. So, I would expect being slightly over the spec for a closed system would not be a major issue.

    If there were an issue, you could always de-scale the HX and/or replace some of the loop fluid to lower the PPM.

    What's going on with the system that has you concerned after 7 years of operation?

  3. Doug Stansbury

    Doug Stansbury New Member

    Thank you SShaw for the information. That is good to hear. I am surprised the Waterfurnace hardness tolerance is so high. I would think it should be lower than that. I have a Hydron unit by Enertech and will have to check their water quality requirements. I noticed some scaling in the flowcenter and that was the cause for concern. I haven't experienced any operational concerns, although we didn't have any exceptionally cold spells this winter in central NY. I only have trouble when the outside temp gets down to -20F or is the less than 0F for an extended period of time.
  4. SShaw

    SShaw Active Member Forum Leader

    Sounds like it's working pretty well then.

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