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Can heat pump water heater freeze pipes in basement

Stolzberg | Posted in General Questions on

We just bought a 1900 farmhouse in rural Massachusetts and were considering putting in a heat pump water heater in the basement, which is unfinished with stone foundation and concrete floor.  Our HVAC guy warned against it, suggesting it could cool the basement too much in winter and freeze our pipes.  So wondering if this is a real problem,  and if it is could we put in a vent system that would allow us to use external air during the winter months and switch over to using basement air during the summer months.

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Replies

  1. Cramer Silkworth | | #1

    Highly unlikely. Most (if not all) heat pump water heaters have a low temp cutoff where they switch to electric resistance backup heating elements around 45F. The basement may still freeze if the foundation is incredibly leaky, but that has nothing to do with the water heater.

  2. Brian Wiley | | #2

    I seriously doubt it. I have a heat pump water heater in our vented crawlspace where there is a small dugout area with pad for mechanicals; we have uninsulated pipes and no real wall insulation to speak of. We’re in zone 5, and it did great all winter. Obviously every situation is unique—like a water heater in a crawlspace—but my guess is that’ll do just fine in your basement.

    Also, mine has the ability to change the mode from eco (entirely heat pump) to hybrid, as well as conventional where it turns off the heat pump. If you were really concerned you could always switch it to conventional during your coldest months.

  3. Jay Thomas | | #3

    I have a stone wall foundation and a concrete floor. Once I put an air barrier on it (1/2 inch EPS) the temps stay around 60 degrees in the dead of winter. (Outside air temperature is 15 degrees) Using a thermal camera to seal is invaluable.

    Not sure where the heat is coming from, probably some combination of ground transfer (almost entirely below grade) and air leakage down.

    Either way, the heat pump works great all winter. The more you insulate the better it will do. Uses about a kw/day and in the summer the de-humidification is really helpful to keep things dry.

    You are much better off insulating than adding venting --- more holes and more air leaking in.

  4. Jay Thomas | | #4

    Only thing I would note though when you have company over switch to high demand mode. :)

    The heat pump only mode could not keep up when we had a lot of people over and ran all the appliances at the same time!

  5. Stolzberg | | #5

    Thanks for the feedback. Do you all think adding a drain water heat recovery pipe would help the water heater keep up during high demand without switching over to electric mode?

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