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Community and Q&A

Forcing Heat Pump Water Heater Mode

user-1140204522 | Posted in General Questions on

I would like to switch from an electric water heater to a hybrid heat pump water heater.
I am in southern NH, so fairly cold in basement in winter.
I don’t want to over cool the basement as it is used by people to some extent.

I have a dehumidifier in the basement which runs for most of the year.

I would like to use the heat pump water heater whenever dehumidification is needed, and when its not too cold down there.  Basically I could make or break a relay when those conditions aren’t met and we’d like to switch to electric mode.

I see notes here and there that if certain sensors fail the units will default to electric only.  Any notes or ideas on any scheme to have a relay switch the heat pump into electric only?

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  1. paul_wiedefeld | | #1

    What about a electric baseboard heater set to a low temperature? Seems cheaper and more reliable. It’d come on if the HPWH cooled the space too much.

  2. Expert Member
    DCcontrarian | | #2

    This seems like an awful lot of trouble for a hypothetical problem.

    I've been living with a HPWH for 18 months now. My workshop is in the basement. I haven't noticed that it cools things unduly.

    If you do find that the cooling is excessive, a better solution is to direct more heat into the basement than switching to resistance heat.

  3. matthew25 | | #3

    I am not exactly advocating for this brand because of the noise issues that have numerous threads on this forum but Rheem’s products do have a smart connect WiFi control option and you could integrate with another smart home system such as HomeAssistant to code this logic for you. But also I agree with others that the cooling output of this unit will not be crazy and freeze you out of the basement.

  4. user-1140204522 | | #4

    Thanks for your ideas. My thinking is compared to now at 100% resistance heating, anything will be a reduction. Maybe it is only in the coldest 20 days I'll want to lock out heat pump? Maybe not at all as @DCcontrarian says. I think I will also be able to turn off dehumidifier, so this all could be a big savings.

    @matthew25 - I hadn't seen that integration feature you mentioned. I just searched a bit now. It looks like HomeAssistant may be open source? I wonder if anyone is using it successfully to control mode of water heater?

    I am open to other brands, its just that Rheem is carried at big orange store with rebates. Maybe others are available too with a little more work.

    1. tobym | | #6

      I can confirm that the Rheem HPWH heater integrates well with HomeAssistant and you can control the modes based on external sensors or other triggers. Not sure if I'd setup HomeAssistant for just this purpose though -- seems a bit overkill.

      1. matthew25 | | #7

        Agreed, I brought up HomeAssistant because it’s the system I plan on using one day when we build our house. Rheem has an app called EcoNet that will let you control the mode just from one app, but if you want it to be more clever and automatically switch based on weather you will need some sort of IFTT type of system. Perhaps iPhone shortcut automations can be used for this?

        And yes, HA is open sources and mainly built on Python. It is brand agnostic which is why I would pick it over other systems like Crestron, Control4, etc. Also free.

  5. walta100 | | #5

    I think the HPWH will remove much few BTUs from the basement and collects much less condensate water than the OP is imaging it will.

    Would a few people who own a HPWH be interested in collecting it water and measuring your output?

    My wild guess is it will be less than a gallon per day on average.

    The computers that run the hybrid water heater are quite complex a simple relay is unlikely to change its mode setting.


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