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I am planning on changing an oil hot water heater to a heat-pump hot water heater — any suggestions?

djt_1971 | Posted in Energy Efficiency and Durability on

Water heater to be installed in a heated basement and the home has 4 people living in it with 2 full bathrooms. Can I use the heat pump to dehumidify as well?

The location is eastern PA.

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  1. GBA Editor
    Martin Holladay | | #1

    Q. "Can I use the heat pump to dehumidify as well?"

    A. Yes.

  2. dickrussell | | #2

    DJ, why do you want to replace the present water heater with a heat pump unit? This has been discussed before. The heat pump will draw heat from the surrounding air and use that energy to heat water. The surrounding air will be cooled substantially, which may be useful in summer. In the other three seasons, the heating system will have to replace the heat removed by the heat pump. In those seasons, assuming the heating system is oil-based, then you won't be saving anything, but would actually lose. Most of the heat that goes into the water ultimately comes from that oil-based heating system, via heating the air, but the balance is the electrical energy used by the heat pump.

    Air-source heat pump water heaters make more sense in cooling-dominated climates.

  3. richmass62 | | #3

    Dick -- I am under the impression that if you put the heat pump water heater in the basement outside the conditioned space, the heat lost will be replaced by ground heat, so with enough insulation on the basement ceiling there is no loss to the the interior of the building.

    This requires of course that the water tank and pipes leading from the HPWH be extremely well insulated, because the basement temperatures are likely to be close to 50 degrees.

    I am considering the same approach here in massachusetts and I am wondering if anyone in a northern climate has tried this. Also wondering if anyone has measured standby losses of heat pump water heaters.

  4. user-869687 | | #4

    Rich, note that the original question was for a conditioned basement, not outside the conditioned space. I think Dick Russell has the best answer here. If you read consumer reviews of HPWH units, people say they don't work particularly well when the ambient temperature is cool, even just into the 60's. They pretty much turn into standard electric resistance units in a cool room. Inside a garage in Miami, they work great.

  5. wjrobinson | | #5

    Unheated basements here drop to 30-35 degrees winters!! Take even more heat out and the temperature goes lower than 30-35 degrees!!

    Heat pump water heaters are for warm homes that need cooling and dehumidifying. (Think Puerto Rico, Cuba, Curacao...

    Once again its amazing how powerful advertising is.

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