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have heat pump water heaters improved in the last 2 years?

acrobaticnurse_Eli | Posted in General Questions on

I’m beginning to seriously consider installing a heat pump water heater but I see many complaints about Rheem that are ~3 years old, with few comments less than 2 years old. It seems that the Gen 4 rheem was generally well received while gen 5 was substantially louder. Does anyone know if the increased noise issue has improved, or have another model to recommend? 

This would go in a deeper section of my encapsulated crawl space, right beneath my laundry room, with no contact with any structural component of the house, so some noise should be ok but I’ve seen people complaining about noise all the way to the second floor throughout the house.

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Replies

  1. Danan_S | | #1

    I think I may have one of the loud generations of Rheem HPWH (installed in 2021). It's behind a wall adjacent to my kitchen and living spaces. I put sound absorbing materials (cork insulation panels) between the heater and the walls around it, and that seemed to handle most of the noise.

    I've forgotten about what sound remains. Perhaps I've gotten accustomed to it, but also there are so many other sources of noise in the house (teenagers) that it really can't compete in terms of sheer annoyance!

    A side note: if your crawl space is fully encapsulated (no air exchange with outside), make sure you duct the air intake and exhaust of the water heater to the exterior, since it needs a constant source of fresh air.

    1. acrobaticnurse_Eli | | #3

      I'm curious about the need for ducting intake/exhaust air for a constant source of fresh air. The crawl space is roughly 1200 square feet and averages 4 feet high with a small section that is just tall enough for a heat pump water heater and accessing the filter on top, totaling ~5000 cubic feet while most heat pump water heaters seem to need about 1000 cubic feet. The crawl space is usually about the same temperature as the rest of the house year round.

      I initially thought about just building a small shed against the house that could be open to the outside 10 months of the year and then use resistance heat the other 2 months, with the potential benefit of less noise transferring to the house, but had thought that installing in the crawl space near where the old water heater is installed would be better if I could make enough room for it. This is for climate zone 3a with heating provided by a single stage heat pump. When the AC/heat isn't running the house is relatively silent as no other appliances make much noise in the living space.

      1. Expert Member
        DCcontrarian | | #6

        You have no need for ducting. In zone 3A the HPWH will help a lot with your air conditioning.

      2. Danan_S | | #8

        If you do it unducted the HPWH will make your crawlspace colder. Depending on the humidity, that could result in condensation in the crawlspace.

        If that's an issue, given how mild climate zone 3a is, you can duct to the outside and for most of the year you won't see much drop in efficiency.

        Perhaps start with the unducted installation and monitor things. If there is an issue it should be easy to add ducting given how much space you have.

        1. Expert Member
          DCcontrarian | | #12

          Just don't duct to the outside. That's not how they're designed to work.

          It's not going to cause condensation, the HPWH dehumidifies and removes moisture. That's one of the benefits. In a properly constructed encapsulated crawl space it will work the same as in any other conditioned space. You're required to have air exchange with the rest of the house, having that cool dry air inside your house is good.

        2. acrobaticnurse_Eli | | #13

          If/when I get a HPWH it will be interesting to see how it affects the temperature and humidity. I keep a sensor in the crawlspace near where I'm considering placing a HPWH. In addition to the dehumidifying effect of the HPWH I have a dedicated santa fe dehumidifier in the crawl space.

  2. Expert Member
    DCcontrarian | | #2

    >A side note: if your crawl space is fully encapsulated (no air exchange with outside), make sure you duct the air intake and exhaust of the water heater to the exterior, since it needs a constant source of fresh air.

    Where do people get this idea?
    It's supposed to get air from inside the building envelope and return it to the building envelope.
    It doesn't need fresh air, it needs conditioned air. It's not burning anything. The last thing you want is outside air, that would completely destroy your efficiency -- which is the whole reason for getting a HPWH in the first place.

    1. Danan_S | | #4

      > It's supposed to get air from inside the building envelope and return it to the building envelope. It doesn't need fresh air, it needs conditioned air.

      The original comment said:
      > This would go in a deeper section of my encapsulated crawl space

      I assumed that an encapsulated crawlspace is probably not conditioned.

      Normally, yes I'd agree that if one is in a cold climate, a HPWH should be put into the conditioned space.

      But absent that option, it seems like they have to duct to somewhere. They could duct to the conditioned space, but they would have to do it carefully to avoid bringing air from the crawlspace to the conditioned space. From what I've seen, that would be near impossible given that the compressor and coils of most HPWHs are exposed to the surrounding space.

      If they live in a place that rarely freezes (looks like they live in 3a), then ducting to the outdoors seems better because it doesn't steal heat from the conditioned spaces or introduce air quality issues.

      1. Expert Member
        DCcontrarian | | #5

        Code requires an encapsulated crawl space to be conditioned.

        Generally HPWH's shut off the heat pump when the incoming air is less than 50F or so, because the coil has no freeze protection. So there's a narrow window where it might make sense to run a HP on outside air, when the outside temperature is between about 50F and 65F. Any colder and the heat pump shuts off, any warmer and you start needing to cool the house and the cooling is appreciated. But unless you live somewhere where it's always in that range, how do you switch back and forth? And in that temperature range there's really no efficiency advantage from outside air, nor is cooling the house a big factor.

        1. Danan_S | | #11

          > Code requires an encapsulated crawl space to be conditioned.

          I didn't know that. Thanks for educating me :)

          > Generally HPWH's shut off the heat pump when the incoming air is less than 50F or so, because the coil has no freeze protection. So there's a narrow window where it might make sense to run a HP on outside air, when the outside temperature is between about 50F and 65F.

          Rheem's HPWHs at least have a heat pump operating temperature range of 37F-145F. That would seem to cover a lot of zone 3a's days. The COP will drop at the lower end of that, but it should still be > 1. I've definitely seen mine operating down to 37F.

          > But unless you live somewhere where it's always in that range, how do you switch back and forth?

          I don't advocate for switching back and forth, but picking one configuration that works well most of the time.

      2. acrobaticnurse_Eli | | #7

        Thank you. It does get cool outside a couple months out of the year, but since I insulated the crawl space walls, removed insulation between the crawl space and the rest of the house, added a vapor barrier to the ground, and a dehumidifier, the crawl space temp generally matches the temperature of the rest of the house.

        My main concern is adding something that will produce irritating noise throughout the house and/or break in 5-10 years. In the mean time I'm maintaining a 25 year old electric water heater while contemplating future options aside from another silent electric resistance heater.

        1. Danan_S | | #9

          > My main concern is adding something that will produce irritating noise throughout the house

          Even if it isn't insulated, since it isn't touching any structure, you'll probably be fine. And furthermore, you said it was under the laundry room, which is probably fine if it has a bit of noise.

  3. jadziedzic | | #10

    There are other brands than Rheem; we have a Stiebel-Eltron Accelera 300E and have been very happy with the performance, and the noise while running (which is mostly the fan blowing air through the coil) is not objectionable.

    Sound Power Level 60dB
    Sound Pressure Level 52 dB(a)

    1. acrobaticnurse_Eli | | #14

      Thank you. The Accelera 300E caught my eye and then I was confused why energy star doesn't list it, though tax credits aren't everything. I like that it uses a powered anode vs a sacrificial one. With any other water heater I plan on installing a powered anode before placing the tank into the crawl space.

  4. freyr_design | | #15

    Ao smith is very quiet

    1. acrobaticnurse_Eli | | #16

      Thank you. I wish it was possible to tell from reviews on sites like Lowes/HD how common a complaint really is. For AO Smith I see very few noise concerns, just compressor failure. It's hard to tell if compressor failure is more likely with AO Smith, or if it's just the main problem left to complain about.

  5. acrobaticnurse_Eli | | #17

    From all that I've read so far I think if/when I get a HPWH I'll get one that it will be manageable for me to uninstall and return locally if needed, I'll check all the connections and elements to make sure nothing is apt to leak, check the ohms resistance on the elements to ensure they're good, make sure it stays upright for 24+ hours before turning on the first time so the compressor is happy, and monitor the circuit with my emporia vue so I can readily see if the heating elements are being used when I'm expecting the heat pump to be doing the work.

    I should also make sure the warranty/return is valid if installed DIY. I know the Sanco2 warranty is only valid if purchased and installed by one of their designated installers. A master plumber that is not on their list would not be covered by their warranty, much less a regular homeowner. I also realize that local rebates would require install by someone on a list my utility maintains, while the federal tax credit doesn't seem to. I imagine no good professional is cheap enough for it to cost less to use them in order to get a $350 rebate, and find I'm often more likely to obsessively check over everything than a professional that needs to get to their next job.

    I may also install a merv 8 filter box on the air inlet to allow for good low resistance clean air just like I did for my ERV, add a full bore ball valve for drainage, and a powered anode so I'm not left trying to switch out sacrificial anodes around the compressor.

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