Hybrid heat pump water heater



My AO Smith HPWH was discovered within a month, but only half of it. One phase reports the compressor cycles pretty accurately, but after 8 months, the other phase still has not been discovered. Strange since they both should be the same.


Another bit to save energy:
Get an Intermatic timer, the one rated for 10,000 watts.
I have my water heater (heat pump only mode) run between 11pm and 7am and set to 140f. By the time the timer commands a shutdown, the tank has had a chance to recoup from both morning showers.

Are you saying that the Rheem EcoNet heat pump water heater doesn’t have a timer mode? And that you needed to buy a separate timer for it? I installed a timer on our current water heater but was hoping that Rheem EcoNet would be able to replace that. Disappointing.


It doesn’t have a timer, but does work with 3rd part apps. You can toggle modes or home/away modes. I believe it “works with nest”. I can control it via home assistant.

Any of these methods achieve the same goal without needing a timer.


Context: We currently have a resistant storage water heater, an Aquanta control unit for it, and solar PV. The rate plan we’re on with Hawaiian Electric means that it to our advantage to have the water heater heat up water in the tank from 10am-4pm daily, and to have us use that water in the evenings and for morning showers. We get $0.15 per kWh sold back to Hawaiian Electric and they charge us about $0.33 per kWh for power they sell us.

Current setup: I’ve programmed the Aquanta to only run between 10am and 4pm daily. It heats up to about 130 degrees and that water is enough to take us through the evening.

Need: Can I integrate the Rheem with home automation so the set temperature is less from 4pm to 10 am? That way I can have it run while the solar is generating electricity and maximize my savings.


Depends on your home automation platform, if they have an integration, they you certainly can do this. I can do this with home assistant.


So home assistant can automate the schedule for the Rheem hybrid water heaters?


Yes, you can change the temp/mode based on anything available to home assistant.

For example: If my wife pushes a button, change the mode from heat pump to high demand. (For large bath tub)

Or: if the time is between 4pm and 10am, set the temp to 120 and change the mode to heat pump only, else eco mode and 130 degrees.



I have installed a Rheem 80 gallon Hybrid Heat Pump. Only been 2 weeks and not identified yet (nor was I expecting it to). I actually got my landlord to install it - he paid for the cost of a standard water heater and the installation costs and I paid the excess over the costs of a standard. So I’m very interested in how quickly it will pay off for me (and hopefully before the end of my tenancy agreement!).

It’s not currently on a timer as I thought the heat loss would be so low that it wouldn’t be worth it. Plus as its only operating in heat pump mode (as we never get below 60F here), which I understand takes longer to heat the water and I wasn’t sure when I should turn it on in time to get enough hot water. 1 hour, 2 hours etc? I do have a circulation pump, which has been off for a year as that was driving my electricity bill sky high and thanks to Sense I was able to quantify the savings from turning it off. When the circulation pump was on for 3 hours in the morning (on a timer) the water heater was actually on for about 90 minutes (as it kept having to reheat cold water). When I turned it off that went down to less than 30 minutes. Twice a day so huge savings each month. So I need Sense to identify the new heater to see if its worth turning the circulation pump back on and stop wasting as much water as I wait for hot water in the shower.

So I have some questions:

Do people use a timer with their heat pump?
Does anyone use a circulation pump and does it cause the heat pump to come on a lot more?
When my circulation pump was off we could not get any hot water and had to go down into the basement to turn it on to have a hot shower (and remember to turn it off afterwards). That was not popular. I think that is functioning as designed though although no plumber was able to confirm that for me. So is there an easy way to turn the circulation pump on from upstairs?


I don’t have the heat pump but do use recirculation for hot water. Your bill was likely sky high from heat loss.
I have the highest R-value I could find and it dropped my heat loss per foot to about 8.5 btu. Bare pipe has heat loss of 40-45 btus.
The best pipe insulation you can buy at hone stores is 2.1-2.4 R-value and nowheee near adequate.


What do you use for pipe insulation


Consider an “on demand” recirc pump; far more efficient. I use the one from www.ChiliPepperApp.com. You have to push a button before each shower, but it only took my wife and kids a week to get used to it.


It’s the same foam material that you find at Lowe’s or Home Depot except much thicker. What they carry is 1/2” thick all the way around the pipe. I ordered from Lowe’s and got the 1” thick insulation. A very important parts is making sure it’s sealed up. It has a built in adhesive strip to help seal it after you put it on the pipe but will also require plumbers tape in some areas.
There is a member on here that knows my setup and he is in the energy efficiency consulting business. He was surprised about how good my results are. So was I.
I run my pump with a timer and a thermostat. The timer comes on for four hours in the morning and six hours in the evening. When the water in the pipes drops by 10degrees, the oump turns on and runs for 3-5 minutes. So it’s not constantly circulating. The pump runs once every 30-45 minutes and it it cost .10-.20 a kWh an hour above what it would cost if the system is off. So at 10 hours a day the most is costs is 60 kWh hours a month and I pay .085 kWh.
Does it waste energy? Yes, some. But the trade off is worth it to me to have instant hot water and we have cut back 1,000 gallons a month on water usage by not waiting for hot water.
By the way, listen to @steve he knows what he’s talking about and suggested the same to me. I had already done mine but if I had to do it all over again I’d be following his advice.
Insulation is Lowe’s item # 13751


I use/recommend doing both. Good hot water pipe insulation delivers significantly hotter water to your faucets, allowing both lower tank temperatures and less hot water flow. Then a controllable circulator (Steve’s recommended www.ChiliPepperApp.com is very cool indeed…wish I’d known about it when I did mine) clears out the standing tepid/cooled water without dumping anything down the drain. In many houses, doing an effective job of the insulation is challenging, due to access issues.

Either one has fairly short payback, particularly if you have electric hot water heaters and live in a part of the country with 0.18/kwh power costs. We did both together and definitely passed our breakeven point several years ago.


I have done the math for the suggestion provided by @steve
I’ve made the best out of what I had to start with (water heater tank) but would recommend the way I’ve done things only to improve what is already in place. For someone replacing things like a water heater, I would say go with on demand.
Half of our water heater total usage in KWH is to keep water hot. That’s when it’s not being used at all.
Not recirculating and not drawing hot water the heater uses an average of .3 kWh around the clock.
That’s 216 KWH a month. I have very low electricity cost but for someone that pays a premium for electricity, they stand to save a lot of money.
Also consider water heater life expectancy is either 6,9 or 12 years. I did get 19 out of my 6 year Heater but that isn’t normal.


What are you doing for pipe heat loss once the pipe goes into your wall?


I don’t have enough loss there to worry about.
my home is on a block foundation with piers and
Beams. All my plumbing is in the crawl space and there is only a couple of feet at the most to each fixture that isn’t heavily insulated. Where it Tee’s off under the house and changes from 3/4
To 1/2 it’s insulated even ont the transition and everything to the floor. Both the showers have access panels so I opened them up and insulated from floor to valves. I thought about using spray foam on the others but don’t think it would save enough to worry about.
i am seriously thinking about insulating on top of the 7.1 3/4 i have now but its going to be expensive and cross the point of diminished return.
There is just not any way possible to get to zero heat loss. The water heater itself is where the majority of my heat loss is due to the large surface area.
Ive tested since installing and tried almost every combination of turning on and off, on a schedule, different flow rate and so much more. i think i can get it a touch better than it is but perfection is just not possible. It’s about the best it can be for a tank system. if i had to do it over then i would follow what @steve suggested and gone with on-demand.
Bottom line for me is I knew it was going to cost money. I had a number in mind where the added cost was worth the convenience and I’ver Actually been much lower on the extra cost than expected. and we are using about 1,000 less gallons of water a month now. If you figure how much less my water bill is, it’s pretty much break even.


When we had to replace our original “builder junk” electric water heater (it leaked after only 5 years), we carefully researched water heater construction/insulation. Note that we had added an insulation wrapper from our local big box store, and it made hardly any difference to insulation efficiency. I’d not waste my time and money on that again.

We found that for a few hundred dollars more there were super insulated models available (NOT at home centers) that are somewhat larger and have inches of dense foam all around the tank. The insulation is so much better that our water heater can sit idle in our 70 degree basement all day and not lose enough temperature to kick in again after morning showers. The new unit dropped our hot water heating bill by a huge amount, so the cost difference has already paid for itself. Sense does reliably detect our new hot water heater (one of the very few things it does) and it shows $250/year at our high NH electricity costs and that’s with incoming water at 50 degrees from our deep well. That’s a BIG drop from our original costs, and we have more and hotter water available.

Note, we didn’t get a hybrid, which were barely available years ago, but my understanding is that most of those do have excellent insulation. They are also MUCH more expensive to purchase but save hundreds of dollars per year.

I wouldn’t rush out to replace a good working unit, but when one dies…they don’t last anywhere near as long as they used to…I’d recommend a high end replacement.


Your right @andy, the box store heaters don’t have good insulation. I made my own “blanket” of sorts. I wanted something form fitting and better than the R-6 blanket they sell.
The water heaters your talking about with super insulation are triple the cost here, adding $700 to the cost of the water heater alone.


We paid about $450 more for our Vaughn Hydrastone Plus Foam unit at our local commercial plumbing supply (builder rate), the price difference of which paid off in just over one year compared to the energy wasting original builder junk. The Vaughn unit has heavier gauge steel, a ½” ceramic lining, and 2-3” of dense foam insulation. They claim that the combination of the ceramic and the foam provides 1/3 degree per hour heat loss and we see a bit better than that in our 72 degree basement.

I would do it again in a heartbeat. Sense did acquire this device pretty quickly and it shows an annual energy cost of about $260. This is a case where Sense clearly showed before and after results.


That’s great @andy
That yearly cost estimate is good and low.
Mine says about $410 which is Lower than the energy guide sticker that shows $424. I have a 40 gallon and there are four of us using it. Hot water is a big expense for us with all the dishes, laundry and showers. The water heater I did purchase also has ceramic coating but not 1/2” thick and 2” foam insulation. I added fiberglass as it’s a better insulator and also have reflective insulation for a vapor barrier.
Yours is definitely doing a good job, I’ll not see numbers that low.
Your also going to get decades out of your instead of years.