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Geothermal loop

Trevor_Lambert | Posted in Mechanicals on

I’m nearing the point of hooking up a heat exchanger to a ground loop (ref: ). I have a couple of basic questions.

1. Do I need an expansion tank, or just a pressure relief valve?
2. Do I need a check valve?
3. For the heating season, I am going to place the heat exchanger above the HRV intake, oriented such that the air flow is in the direction of gravity. I am assuming that in this case I would not need a condensate drain because the incoming air is going to be hitting a warmer surface, plus even if there is any condensate it will just fall into the HRV where there is drain. I plan to relocate the heat exchanger in the cooling season to above the HRV supply port. In this case, there will definitely be condensation on the coil. Is it still ok to just let that fall back into the HRV and go out through its condensation drain? If not, I can try to fit a 90deg bend before the heat exchanger, though this might be tricky and will make the seasonal position change more work. Or maybe I could just tilt the exchanger a few degrees and have a drain on the low side of the tilt.

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  1. GBA Editor
    Martin Holladay | | #1

    You should follow the installation instructions provided by the equipment manufacturer.

    Zehnder has an installation manual for its Comfo-Fond system. Here is the link: "Comfo-Fond Installation Manual."

    The Zehnder manual mentions an "expansion vessel" (presumably, supplied as part of the equipment) as well as a condensation drain (see image below).

    If you are installing Ultimate Air equipment, you should contact Ultimate Air for installation instructions.

  2. Trevor_Lambert | | #2

    Hi Martin,

    I am using a Zehnder HRV, but not their Comfo-Fond (too expensive and too big). I guess I am the manufacturer of the pre-heater system, and I find my instructions somewhat lacking. A case of getting what I paid for.

  3. Deleted | | #3


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