Hybrid heat pump water heater

I am waiting for it to pickup the HP portion of my AO Smith, from using the Other when it is on I am guessing 400-600 watts. Would love for Sense to pickup the HP on it but I have only had it for a few weeks now.

I have the Rheem 50 gallon, I’ve run it in heat pump mode from the beginning. I actually complained in the EcoNet app review section that energy saver mode was misleading. I ran it in electric resistive mode for a week just to see the efficiency difference. In that mode Sense labeled it as other.
I’ve only had my Sense since December 1st so I guess it’s still early days.

Watching this for about two years now, and can state that “your experience may vary”. Some folks find many/most of their devise in a month or two, some don’t find most of them after years. Best of luck with your situation.

Thanks to you and other recent responders regarding the thoughts about heat pump water heaters. We have a vintage (22 years old) water heater in our summer camp and definitely need to do something about that in coming months. Sounds like you are glad you made the choice you did, and that will influence our decision.

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I had an oil boiler previously for domestic hot water. I’ve only had my HPWH since April but couldn’t be happier with it. My local electric company gave me a $350 rebate do the decision was pretty easy. I figure if/when something regarding the heat pump breaks it has resistive rods until I get it fixed.

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Huge thanks for that pointer…we should check with the power company for incentives. That could make the cost purchase similar to a conventional heater.

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I also have installed a Rheem last year. If you connect it to your home’s WiFi, you’ll get usage data. It appears my Sense is under reporting, showing only half of the usage data. It doesn’t seem to matter which of the 3 modes I choose:
Automate Savings, Most Efficient, High Demand

I wrote extensively about my experience with this water heater here:
Replaced my failed gas water heater with a much more efficient Rheem hybrid electric with WiFi, its quiet heat pump is also dehumidying and cooling my basement

and in this section I have screenshots of the Sense data versus the Rheem data.

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Same here, sense under reports my Rheem hybrid.

I have a GE Thermospring Heat Pump water heater and it also isn’t being detected. I really wish they would enable detection for such an important device!

Sense sort of found my HPWH, well part of it. For instance my EcoNet app says my HPWH has used 186 kWh this month but Sense says it’s used 25.8 kWh

If you’re using 186 kWh in a month with your Rheem there is no way that you’re running heat pump only. Check to see if you’re running in energy saver mode.

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No it is in heat pump mode, I have it in a well insulated unheated storage room that is indirectly heated through a couple of central air vents I have cut in the wall behind my refrigerator. It is pulling air from behind my refrigerator which is approximately 70°. In the summertime I had it pulling really hot air from my attic in the summer and my usage was more like 68 kilowatt hours a month

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Loving this …

Like many, I suspect, I’m frustrated that I can’t dump the heat from the fridge directly into my HW tank, at least in summer. Short of some complicated refrigerant heat exchanger, pulling the warm air in that way is nice.

Remember those old alarm clock + kettle + toasters & “everything including the kitchen sink” kitchens that you get in small seaside hotels … well how about a MFHPHW?!

MF = Mini Fridge

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That would be nice. In the summer my HPWH was only costing me $10 a month pulling that hot attic air but that’s not an option in the winter here. I ran it in electric resistance mode for a week and the usage was much higher even pulling cooler air (70 degrees approximately) in my winter mode. Now not only is my HPWH using more electricity but my Mitsubishi mini splits are working harder to heat the house because the HPWH is stealing house heat. I’m curious if switching to pulling hot air from the attic is worth it in the summer as continuing to pull air from the house will help my mini splits when in air conditioning mode. So maybe the extra $10 to $15 a month spent on hot water will be mostly offset by easing the ACs load?

The trick of course is to switch the air intake (and outflow) in summer and winter.

Here in the northeast in a small apartment an as-is HPWH would be great in summer drawing heat from my apartment and dumping cool air. In winter it’s exactly what I don’t want … especially given that my heating is 100% resistive … and so in winter (without switching the air IO around) my place would probably run more efficiently with the HPWH in resistive mode.

Well I agree with 100% resistive heat You’re not saving anything in heat pump mode but from what I’ve read on various websites my Mitsubishis are efficient to the point where even having my HPWH steal heat from them I’m better off than having my water heater in resistive mode. I can’t pull air from my attic in the winter here in the suburbs of Philly because it’s too cold up there and I wouldn’t want to anyway so I’m pulling heat from the house. My question is in summer time I know that the really hot attic air makes my water heater more efficient but if I keep it in winter mode where it’s pulling warm air from behind my refrigerator and dumping cool dehumidified air out even though it is working harder than using the attic air is the fact that it’s helping my mini split air conditioner going to offset or maybe at least mostly offset the increased HPWH electrical usage from not pulling from the attic? It’s probably close to a wash in my opinion. That’s my winter mode duct…

It’s probably, as you say, “a wash”, but …

More efficiency in your case, if I understand your setup, could come from un-insulating the HPWH room in summer … i.e. the cool air output by the heat pump could cycle into a conditioned (by your mini-split) space vs being trapped in the insulated room and effectively working against the heating aspect of the tank. Leave the door open?

In winter, yes you want to draw the warm air (pre-conditioned by your fridge and more efficient mini-split) from the living space but you also, ideally, want to vent the cool air to the outside away from the “warm space” insulating the tank.

OK, I’m adding that the MFHPWH should also have an ice maker or can chiller :beers:

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I floated the idea of keeping the central air vent ( maybe adding another?) behind my fridge open in the summer and letting the cool air from the HPWH enter the house but I wasn’t sure if having basically an 8" hole between my conditioned space and my attic was a good idea considering the HPWH doesn’t run most of the day. I was thinking when someone showers or runs the range exhaust fan the vacuum created would pull air from the 8" duct to the attic as that would be the easiest source as the attic has ridge and soffit vents. So my storage room door ,which leads outside, has a large vent in it from when there was an oil boiler in there and it needed the intake air during the summer. I left that door vent open in the summer so when the HPWH was running the room wouldn’t become pressurized. When it got cold(ish) I sealed the door vent with poly board and HVAC tape, opened the central air vent behind my fridge and swapped the hpwh’s intake vent from the attic to behind the fridge… phew

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The interplay between hot-water-on and bathroom exhaust (shower mode) starts to get complicated. Eventually the only real solve is a heat exchanger (HRV/ERV) and ductwork. Seems like we have similarly obsessive concern … I start to wonder whether the excess heat my thoughts are generating could likewise be a factor! At least it’s cold right now.

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I thought about a (HRV/ERV) but probably not doing it at this point. That’s funny I did think that in my summer setup when someone showers ( exhaust fan on ) the HPWH would be on hence the air would be cool coming out plus the opening to the vented attic would make life easier on the bathroom exhaust fan. Problem is showers aren’t the only time the fan runs and then there’s the dryer…with the dryer running I’d be exhausting cooled conditioned air and drawing in really hot attic air.
It’s part about the money but I think it’s just as much a sort of hobby. Only certain people can listen to all the different permutations regarding ducts run where, vents opened or closed, air flow and temperature etc…

I’ve labeled my Rheem Hybrid water heater in my Sense inventory. Given Rheem is apparently having issues with the reliability of their monitoring, do you have any ideas about ways I can improve detection by Sense?