Hot water Heat pump, anyone running them in their house?

[Eber]

I have a Rheem hydbrid hot water heater.
Girlfriend takes a marathon shower, uses up all 50 gallons of hot water (120F)
and it takes about 4-5 hours to recover. My unit takes about 500W . I love it.
it is always on the Solar system and never on the grid.

 

[OffGridInTheCity]

I have a Rheem hydbrid hot water heater.
Girlfriend takes a marathon shower, uses up all 50 gallons of hot water (120F)
and it takes about 4-5 hours to recover. My unit takes about 500W . I love it.

Yea, my daughter when still living at home would run the shower till all the hot water was gone! Me - I'm 5min tops

 

[1201]

I think the location / ambient temps make a difference, as well as amount of hot water - e.g. we do ~300ft of hot water recirculation for 'instant hot water' at the bathrooms at opposite ends of the house.

Here's my kwh/month the last 2 years with (I think) the major factor being ambient temp under the house of 55F winter and 75F summer. I presume that attic install with higher temps would make it significantly more efficient. On the other hand, I'm surprised it works as well as it does at 55F
View attachment 197476

Thanks for posting this. It's nice to see real world data on heat pump water heaters.

Here is my 40 gallon electric resistance water heater data. 2 adults and 2 soon to be teenagers
Averaging 244kwh a month

 

[drps10]

I have a 40gal 4500w dual element 14 yr old hotwater tank. Last month we used 5000gal. Family of 6 oldest is 13 and youngest is 5.

 

[Ampster]

I have been using heat pump water heaters in my homes since 2014. I also put one in my nephew's second home. He loves being able to turn it on or off remotely when planning a visit. He is an IT professional and I helped him wire WIFI thermostats for the baseboard heating. Maybe I can convince him to install a heat pump for heating but that house is surrounded by forest on the Medocino coast and he has several fireplaces.

 

[PhilIA]

I have the Rheem 80 gallon. It was only a couple hundred more than the 50 and I wasn't limited on space. House of 4, who are not conservative on hot water. In-laws or my mother tend to visit every month. Temp set to 140 degrees otherwise one of the showers would not have enough flow at a warm temperature. 2x baths a day about 4 or 5 times a week using a claw foot tub. We have never ran out of hot water, but probably were close a few times. I think we even had 3 baths and a shower between 6pm and 10pm a few times. Laundry is usually on cold/cool. 50-55 degree or so well water, doesn't change much throughout the year.

Mine is set to energy saver, nominal draw is about 400 watts about 8-12 hours/day, but will draw up to 4.5kw for limited periods during high draw. Installed late 2022. 2023 we used 2037kwh according to Emporia for the hot water heater although this year we're trending less. Peak months(Nov-Mar) were about 200kwh, other months about 150kwh. I set it to standby if we leave the house for a few days, but otherwise leave it at 140 degrees.

SW Iowa. Basement is around 60 degrees in winter, about 65 in the summer. Heat pump air outlet temp around 50 degrees. Absolutely no regrets. Rural, no natural gas available. For us a heat pump beats propane pricing down to a COP of about 1.25. $.11/kwh summer, $.10 winter but $.06 after 1000kwh electric rate. Last fill on propane was $1.45/gal(summer fill), currently $1.65. It does a great job of dehumidfying. Fully open basement, 1800 sq/ft. I don't find the sound intolerable in the basement(workshop with TV), but would want it in a well insulsated room if it was on the main floor.

 

[drps10]

More great information. I’ve been scouring the internet for information like this and can’t find it. Love this forum.

 

[enwinn]

I'm leaning toward the SANCO2
https://www.eco2waterheater.com/product-info

Jake goes through a lot of points and features in this video:

 

[enwinn]

Good comparison video of HPHW for 2024

 

[Quattrohead]

Cool down the garage but don't throw that energy away.

So in my Florida garage I have my hot water tank and a beer fridge plus three inverters and six batteries. At 9:00 a.m. this morning my garage was at 90 degrees Fahrenheit and my beer fridge and inverters are showing signs of stress. I had thought about putting in a mini split but decided to go...

diysolarforum.com

 

[drps10]

I'm leaning toward the SANCO2
https://www.eco2waterheater.com/product-info

Jake goes through a lot of points and features in this video:

Would love to see numbers of recovery time to bring temps back up in northern climates.

 

[Partimewages]

Math for recovery is pretty simple.
1 btu will raise 1 pound of water 1 degree F
1 watt equals 3.412 btu's.
1 gallon of water is 8.34 pounds.

 

[67BGTEV]

I've the 50g Rheem Platinum Performance Hybrid HPHW installed in late 2021 for a family of 4 in SF Bay Area.
Both my sons (each) are athletes and use 2/3 of the capacity heated to 130F.
I've programmed it to hear to 110F from 4pm to 11pm!; 120F from 11pm to 5am; 130f from 5am to 4pm. I'm trying to avoid hearing during peak TOU.
During winter it takes about 4 hours to recover from empty to full set to 120f, but doing summer, it takes 2.5 hours. My energy usage for the water heating is 2kMWh.
In Aug 2023, the thermistors went bonkers and Rheem sent replacements and I was able to replace those. This is a known issue with most of the Rheem manufactured units and there are many videos to help diy.
If your unit is 18 month old, call them and have them ship it to you, so that you can quickly replace them when they go bad.

 

[Danke]

Summer it’s a bonus. But if the unit is inside, during the winter one would need to factor in the extra energy used for heating the home because of the heat pump water heater.

 

[Brightside]

We have a 40gal Rheem HPWH. Installed in 2021. Just had the issue with bad thermistors causing evaporator temp errors. The unit would ice up or just alarm out and automatically switch to the 4500W heating element. Just put in the new thermistors and it's working fine again. So unless you diconnect the element, you need a way to run it, in case it kicks in.

It's installed in our laundry room attached to the living space. I put in a 8" duct from the ceiling of the living space to the HPWH inlet. So I suck the hot air off the ceiling to heat the water efficiently. The cold air is discharged into the laundry room and back into the living space. Recovery takes a few hours if all the hot water is depleated.

In summer it works as an AC depending on how much you use hot water. In winter I just add another log to the wood stove, when it's mild, I just use the house heat pump to bring in warm air. It dehumidifies all the time.

I got it because we had an electric on-demand water heater, and there is no practical way to run one of those off an inverter. I'm happy with the performance of the unit when it's functioning properly. Only uses about 400W when running.

 

[drps10]

Only uses about 400W when running.

thats the best thing about them! I just don't think I can buy one because of the laundry room being small. I know I could duct it like you just did, but them I'm heating more with the heat pump to heat hot water and not saving anything. The recovery time is kinda of long for my large family too. If it was just 2 of us, I would consider it more so. Thanks everyone for the information, very helpful. And feel free to keep commenting people! This is all great info for people considering and might saw them to pull the trigger and buy one.

 

[Danke]

I’m just putting large electric water heaters on my future build using the smart load feature of the inverter. So they draw electricity when the batteries are above a certain percentage (nearly full). I set the temperature to the highest setting to dump excess PV into them. Two 120 gallons feeding a 50 gallon. Also, the 120 gallon ones can be heated with my geothermal heat pump system, supplemented with resistant heating if necessary. I hope to last through any cloudy weather with that much heated water stored. Those three tanks together are less than $3,000. And are virtually maintenance free.

 

[Eber]

I’m just putting large electric water heaters on my future build using the smart load feature of the inverter. So they draw electricity when the batteries are above a certain percentage (nearly full). I set the temperature to the highest setting to dump excess PV into them. Two 120 gallons feeding a 50 gallon. Also, the 120 gallon ones can be heated with my geothermal heat pump system, supplemented with resistant heating if necessary. I hope to last through any cloudy weather with that much heated water stored. Those three tanks together are less than $3,000. And are virtually maintenance free.

Is that much hot water for heating the home too?

 

[Danke]

Is that much hot water for heating the home too?

No, I’m using geothermal water to air.

 

[edward4]

I’m just putting large electric water heaters on my future build using the smart load feature of the inverter. So they draw electricity when the batteries are above a certain percentage (nearly full). I set the temperature to the highest setting to dump excess PV into them. Two 120 gallons feeding a 50 gallon. Also, the 120 gallon ones can be heated with my geothermal heat pump system, supplemented with resistant heating if necessary. I hope to last through any cloudy weather with that much heated water stored. Those three tanks together are less than $3,000. And are virtually maintenance free.

I have a Rheem 80 gallon HPWH. It integrates with Homeassistant very well allowing you to create automations that can change operating modes and temperature based on almost any information flowing into Homeassistant. You can effectively make it a dump load whenever you need without any special wiring back to the inverter directly.