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Community and Q&A

Sizing a Heat Pump Water Heater to Qualify for Rebates

Pott0120 | Posted in General Questions on

I am building a new home in climate zone 5 in Salt Lake City Utah. I have a family of 5 and a fairly large home at 3900 ft2. My dilemma is I want an 80-gallon heat pump water heater, but my local utility offers $700 rebate on 55 gallon or less in size. I can use up to two rebates, so it is $500 cheaper to buy two 50-gallon water heaters than one 80-gallon water heater. I considered installing them in different locations, but the best location is my centrally located utility room.

My options are:
1) Buy a 50-gallon water heater and hope it is big enough.
2) Buy two 50-gallon water heaters and install in series collecting two rebates. Installation cost might wipe out my $500 in savings (TBD).
3) Spend a premium on an 80-gallon water heater.

Side note: Unless someone convinces me, Rheem is no longer extremely loud I was going to buy AO Smith.

Any recommendations?

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  1. walta100 | | #1

    Given the size of your home you may want one heater at each end to shorten the wait time for hot water.

    You might try monitoring your current home hot water usage to help you decide if you can live with 50 gallons.

    Note the 50- and 80-gallon units likely have the same size compressor and refrigeration system. So the larger unit only has a bigger storage tank.

    One has to wounder how much longer Rheem can continue falsely advertise 49 DB sound rating in the face of so many higher field measurements.


  2. Expert Member
    Akos | | #2

    The simplest would be to get a standard resistance tank water heater as the 2nd tank. You would plumb the resistance tank in after the HPWH in series. Set the temperature on the resistance tank a bit bellow the HPWH setpoint. This way the only time the resistance tank would run is if the HPWH can't keep up during very large draws which should only rarely if ever happen. This will get you much more first hour draw capcity for less cost.

    If you have long runs, you can also place the resistance tank on the other side of the house to get faster hot water without needed a recirc setup.

    For a new home the simplest way to stretch your water heater capacity is to install drain water heat recovery. With a bit of careful planning, it is easy to route all the drains to a single large unit in the basement. This is very simple install at build time, doesn't cost a whole lot and is pretty much a passive near zero maintaince item.

  3. Expert Member
    DCcontrarian | | #3

    I have the AO Smith and I can hear it in every room of a 4000 SF house.

  4. Pott0120 | | #4

    Thanks for all the feedback. I will look into the heat recover drain and possibly the extra resistance heater.

    What brand of heat pump should I buy? If Rheem and AO smith are too loud what is the next best?

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