The Plug-in Heat Pump Water Heater Is Here!
The 120-volt plug-in heat pump water heater is here! The effort to bring these things to market began in 2018, and now they’re available to buy. This technology has some significant advantages over the standard 240-volt heat pump water heater. But it also has a drawback. Let’s take a quick look.
The big 120 V plug-in advantage
The 120-volt plug-in heat pump water heater requires, well, half the voltage of the standard models, like the one I have in my basement. Any electrical device that uses 120 volts can be plugged into a standard outlet whereas 240 volt devices need special wiring and connections. You can plug in a 240 volt appliance to an outlet with a special plug and outlet. Think electric clothes dryers. Most 240 V appliances, however, are hard-wired.
The thing about 240 volt appliances, though, is that you need more than just a different kind of outlet and plug. You may need three changes to make a 240 V heat pump water heater work in your home. First, a 240 V appliance probably needs two breaker slots in your electrical panel. That could mean you need a bigger panel or to have an electrician rewire things within.
Second, it also uses more electricity. That could mean having to upgrade the electrical service to your house. If you’ve got, say, a 100 amp (A) service, you may need to upgrade to a 150 A service to install a 240 V heat pump water heater. (See my second article on electrification, though, to find out more about panel upgrades.)
Third, you’re going to have run a new circuit from the panel to the 240 V heat pump water heater. This will require paying an electrician to open the panel, run the wiring to the water heater location, and set up the connection. When I electrified my 1961 home in 2019, I replaced the old fossil gas water heater with a 240 V heat pump water heater. The electrician charged me $600 to install the 240 V circuit.
So the big advantage of these new 120 V plug-in models is that they can save you thousands of dollars avoiding changes to the electrical system in your home.
The 120 V plug-in drawback
As you might expect, the lower voltage delivered to the plug-in heat pump water heater means less ability to heat water. That’s because it also gets less electrical power. The 240 V models are called hybrid heat pump water heaters because they have three ways of heating water.
They can use the heat pump. They can use electric resistance heating elements, the same kind you’d find in a standard electric water heater. Or they can use both the heat pump and the electric resistance.
With the 120 V plug-in models, you don’t get the big electric resistance heating elements that come with the 240 V models. Some don’t have the backup heating element at all. That’s great for efficiency, but it may limit your hot water.
I say “may limit your hot water” because the real difference between 120 V and 240 V heat pump water heaters is how much backup heat is installed. I have a 240 V model and keep it in heat-pump-only mode unless we have extra people staying with us and need faster water heating. That’s happened only once in four years though, but we do have the 80 gallon model.
Is a plug-in heat pump water heater right for you?
Heat pump water heaters use only a few hundred watts of power when they’re using only the heat pump. The highest I’ve seen mine go since I started monitoring my electricity last year is a bit above 400 W. Since I almost never turn on the electric resistance heat, I could have gone with an equivalent 120 V model.
What it comes down to is how much hot water your heat pump water heater can make and how much hot water you use. Well, I guess another factor would be how afraid you are of running out of hot water. We’ve had that problem only once with guests in the house.
If you have the electrical capacity already or are building new, you should be able to do it without adding much cost. In an older house that would require significant changes to your electrical system, the 120 V plug-in model can save you thousands of dollars.
Two ways to make 120 V plug-in heat pump water heaters go further is to get one with a larger tank or make the water hotter and then use a mixing valve to drop the temperature before use.
Heat pump water heater resources
There’s a lot of really good information available about both kinds of heat pump water heaters. See the related articles below for what I’ve written on this topic. Here are some other good resources:
- Canary Media published an article about the new plug-in models.
- The Advanced Water Heating Initiative (AWHI) has a lot of great info.
- The New Buildings Institute published an article about a 120 V plug-in heat pump water heater study and the report on that study. The study is title, Plug-In Heat Pump Water Heater Field Study Findings & Market Commercialization Recommendations and is available as a free download.
Today is Heat Pump Water Heater Day!
Finally, whether you’re interested in the new 120 V plug-in heat pump water heater or the standard 240 V models, you can celebrate Heat Pump Water Heater Day. So post a photo online of you hugging your heat pump water heater if you have one. Here’s mine:
The event is hosted by the Advanced Water Heating Initiative and there’s a full agenda for the day on their site, including webinars, resource drops, and more. Check it out!
Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and is the author of a bestselling book on building science. He also writes the Energy Vanguard Blog. For more updates, you can subscribe to Energy Vanguard’s weekly newsletter and follow him on LinkedIn.
Related Articles
Living With a Heat Pump Water Heater
Can a Heat Pump Water Heater Replace an Air Conditioner?
Will a Heat Pump Water Heater Freeze Your Basement?
Preparing an Old Home for Electrification, Part 2
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Are plug in heat pump water heaters as efficient as a 240v heat pump water heater in high efficiency mode?
Love the photo of the hug on National heat pump water heater day!
Interesting product so it frees up an existing 240vac connection in an apartment so it can be used for a dryer upgrade. Be interesting to read the reviews about how these water heaters stack up against the 240 volt models. Are they cheaper to buy verses the 240s?
Go for a heat pump dryer and you don’t need to upgrade electrical service there either. Bonus is that by not blasting conditioned air out of the vent, you’re saving on heating/cooling as well. We’ve had our heat pump dryer for a year, and won’t be going back.
Since I can’t find a way to comment on the article I found I can comment on a post one thing that the article missed is it makes it possible to have a heat pump water heater on low budget solar system since on low budget solar all I have is 120 my neighbor down the street also has low budget solar system no grid tie so no 240.volts now all we need is 120 volt heat pump dryer and we are all set
This Old House has a YouTube video where they install a heatpump waterheater. But the tank and heatpump are separate units, which seems like a good idea. Sanco produce a split system C02 heatpump waterheater with the heatpump outside, which seems like the good standard.
Do you know if Rheem has fixed the major noise problem with the newer versions of your water heater?
110v Rheem. I put mine outside in a standard shelter, earthquake straped to the house, only option. It is right beside the bed we sleep in and wife and I noticed low noise the first night but immediately got used to it. (1903 house, true 4″ studs filled with icynene, NO sheathing or house wrap). It seldom kicks on at night since not in use, AND you can modify the schedule using your cell phone app to set the temp to very LOW at night. Unfortunately the app cannot schedule “off”, but you can do it manually.
I have a mid-2023 production Rheem HPWH and the noise is on par with a ’90s fridge. It’s in the basement, so you can only hear it if there are no other noise sources in the house (which is rare).
Something that’s often missed in these articles is how often a Heat Pump Water Heater is replacing an existing electric water heater. In a lot of cases, there is no wiring change, the difference is mainly due to condensate drain requirements.
My biggest concern is the reports that these are noisy. The rheem seems to be noisier than when it first came out but it is hard to substantiate these claims. The unit will sit under my bedroom in the basement so noise is a big issue
I can’t speak to newer units, by my 2016 Geospring is quite noisy. It is installed in a utility room adjacent to my kitchen and dining room. I insulated the walls to the utility room and installed a solid-core door with weatherstripping, as if it were an exterior door. Problem solved – the Geospring is virtually inaudible when the door is closed.
I installed the GE Heat Pump WH, 10 years ago in daughter’s house.
Some facts: if you already have an electric wh, you likely have 240 vac installed.
240 does not use more electricity than 120. You pay for Kwh, not volts.
Noise has not been an issue, unit is in basement, do not hear it upstairs.
The unit helps air condition the basement, so a condensate drain is needed.
I kept the electric water heater, in line with the heat pump wh.
We rarely turn on the electric unit, as the heat pump unit is always forwarding hot water.
We changed the sacrificial anode at about 8 years. All water heaters need this done to preserve the tank.
We have used the wh to heat the basement floor which has radiant piping in the slab.
The house is all electric, 3900 sq ft, monthly electric bill aprox $100, dual heat pumps.
To help the heat pump wh, I installed a metal duct from attic above the radiant barrier to a position just above the wh. It has a filter box in the attic, a damper and duct fan in the tube. When the attic temp is above 85°f, the system blows hot air into the heat pump wh.
Do you duct the air to the conditioned space or use it to dehumidify the basement? Any issues with overcooling?
110v Rheem. Put mine outside, South California has plenty of warm air to pump from. Would have liked to put it in the conditioned attic to keep that cool since it is warm year around, but not willing to run plumbing up there. But outside it cools the bedroom wall, and condensate has kept my avocado trees watered and happy for a year now.
Actually Allison, you’re way off on your timeline. We built about 10,000 heat pump water heaters in 1980-1983 and most were 110V. We also built 220V but the 110V units did a great job supplementing solar water heating back in the day.
We were quite obviously decades before our time and back then we relied on State and Federal tax credits and utility company incentives to be cost effective. We also relied on escalating electric and gas costs, but that really hasn’t been as severe as we predicted.
As Chief Technology Officer of The Oregon Water Heater Company and later the Oregon Heat Pump Company, I learned a really good lesson about Americans’ expectations for comfort. If the heat in the home went out the homeowner would call for a service tech and schedule an appointment in the next day or two or three. They’d wear an extra sweater and maybe light a fire in the fireplace and patiently wait. If the water heater failed all Hell broke loose and if we weren’t out there to repair it in a couple of hours, we got an ear full! This lack of tolerance is also the reason tankless water heaters have never taken over the market. They’re just too slow for most Americans spoiled by the faster delivery of hot water we’re accustomed to.
It’s been nearly 40 years since I’ve owned a HPWH. I think it’s time.
Love this new tech! Another benefit is a small dehumidifier for the room its in.
Time of year could also affect the capacity(winter vs summer):
-air temperature in the location of the heater
-temperature of the water going into the heater
Allison,
I also have a 240V hybrid electric water heater (A.O. Smith 50 gallon); it has been installed since we moved in our home in May 2022. There are (usually) 3 occupants in our home: my wife, my youngest daughter (senior in college), and I…and a yellow lab and a house cat. Initially, I did the default and left it on “hybrid mode” for the first month. That month, my eldest daughter lived with us for the month before her wedding (4 occupants), but the last week, we hosted all four of our adult children (6 occupants) PLUS my daughter’s 6 bridesmaids for a few days. I was nervous about the hybrid keeping up with the demand, but it came through like a champ! I nervously asked all occupants (10 adults for 2 days), and no one complained about a lack of hot water (maybe they were just being nice…;) Not being sexist, but of those 10 adult occupants for 2 days, 8/10 were adult females…taking adult female showers.
Anyway, after that, I change to “efficiency” mode and it has stayed there ever since. Now, occasionally, I ask my wife and daughter about hot water and they get tired of telling me they have never had an issue with not having enough hot water.
At the beginning of October 2023, I installed an Emporia Vue, and as of today, 10/25/23, my October usage is 28.8 kWh, and my monthly peak 15 minute demand is 2.44 kilowatts.
I am impressed with my hybrid water heater (and if I had the option at the time, knowing what I know now, I would have gotten the 120V option); I HIGHLY RECOMMEND it!
So why don’t we put a 40 gallon unit in each bathroom? Then there would be no delay in getting hot water for your shower, and when the heat pump kicks on after your shower, it will help dehumidify your bathroom without running the exhaust fan. If you use a water-saving shower head (<1.75 gpm) that would give about 20 minutes of shower per tank.
I replaced a gas water heater in 2016 with a Geospring. The gas water heater was my only combustion appliance. I discovered that I was paying a “delivery charge” of around $20/month to the gas company, plus the actual cost for the natural gas used. When calculating a payback period for a hybrid heater, one should keep the savings accrued by cancelling gas completely. I cancelled my gas service and have saved about $250/year on delivery charges alone – almost $2,000 over 8 years.
The cost of the hybrid heaters has almost doubled since I purchased mine in 2016. My Geospring from Lowe’s cost $900 in 2016. The least-expensive models now cost about $1700. It looks like the new 120V Rheem ($2000) costs about $300 more than the equivalent 220V model ($1700) from Home Depot. Less features for more money?
Hey Allison. Building a new home and installing heat pump water heater system. I believe you had or talked about a recirculating pump system in your home?? Do you have any input to that along side of the HPWH.
Really enjoy your blogs.
Thanks
I DO have a recirculating hot water system and it works great with the Rheem 110v HPWH. I notice no difference from the old gas. I do use the Rheem app to schedule the heating for morning and evening when we are home. The hpwh uses very few kwh, I need to get a monitor on it soon. And I use an Emporia “Smart Plug” to schedule the water pump to match. I think the pump uses more kwh than the HPWH, but as I said I need to measure it. And if you get the urge to shower at 2am, the apps can turn on the HPWH and the Emporia from your cell phone
Not my Rheem a year ago, Novembet, and it has performed wonderfully. It was prerelease, and I ended up working with them because the app was not ready.
Great post, and timely. I have a 2007 Noritz tankless that is going to die one of these days and I’d like to replace with a HPWH, preferably a 120V version since the location was wired for a gas appliance.
The biggest thing I’ve had a hard time understanding is the consequences of cooling my basement in the winter (Colorado). It is finished and semi-conditioned. In the summer it keeps itself a pleasant 65-70F. In the winter, it would drop to 50-55F on its own, and I use a little electric space heat to bring it back to 60-65F.
That makes it seem like, in the winter, I’d just be feeding electric space heat to the unit, lowering its effective efficiency by quite a bit.
Is there any recommended way of thinking about this / calculating the impact to confirm that the summer savings outweigh the winter costs?
I believe people are over thinking the cooling/dehumidifying effect of the HPWH. Sure it’s a minor factor but my Richmond 50 gallon HWHP (Menard’s Rheem) only uses about 2kwh/day. Spread that over 24 hours and its probably a negligible temperature difference unless you have the unit in a really small room. I’ve noticed no real affect in my basement that is only a couple of degrees cooler in the winter and I would mainly attribute that to the colder wall.
I installed a Rheem 240V 50 gallon this summer. It was heavy/difficult to move into the basement. So far it has provided plenty of hot water for 3 adults. We keep it on heat pump only mode.
It cost $1900 from Lowes/HD. I received $800 rebate from our local utility and should get a rebate on Federal Taxes of 30%, so it is comparable to buying a regular natural gas or electric water heater.
The anode looks difficult to replace and I’m not sure how many plumbers know how to service it if I have a problem.
You people act like this is some big new thing! I’ve had an add-on HWHP since 2009! It just now took a dump on me and is no longer made sadly. From Nyle Corp. It was called Geyser. Worked great but was a bit noisy. 110V. When price of these stabilize maybe I’ll get another one but not at over $2K!
İf 120v is supplied with up to 100amp, that means 12kVA of power. The same power can be delivered via 240v with only 50amps. The claim that you need upgrade doesn’t sound right
Nobody has a circuit in their house that supplies 120Vac at 100 amps.
Curious about your opinion of the SanCO2 water heaters.
I just put in a new water heater in Hawaii, which would have been the perfect climate for a heat pump water heater. But the only models available had such lousy reviews that I couldn’t risk it. Why can’t they make these more reliable?
Cindi…I’ve had one of the very first “add on” HWHP’s since 2009, it finally died last summer. It only drew 5 amps of power on it’s 120V outlet. That’s efficient to begin with! The other “inefficiency” of course is that they are SLOW to recover, but the trade off of electric savings far outweighs it. I’m in the Great Lakes region, my tank is in the basement, an almost consistent ambient air temp of 58-70 degrees between winter and summer, respectively. It works fine. And as I understand it, at least hope too, since I’ve got a new “all contained” 120V plug in tank on the way, is that they are getting better at efficiency, i.e. better recovery times. It’s just me and the wife, so we don’t notice much problems. Get one!
P.S.: I’m lucky too, in that we’re on solar as well as a 1.4Kw Bluetti “off grid” solar generator, that I’ll be able to go back to running the HWHP from that, making my hot water totally free, rather than suck it off the main large solar array at least during the day. Best of both worlds.
Just finished 25 houses in Pittsburgh and one thing I’ve not seen emphasized is that without a flue they can be located anywhere, so we set them in the basement directly below the kitchen, radically shortening time to deliver hot water.
Located anywhere is slightly misleading. Basements are great but a small room or closet like someone might try in the south without a basement would probably not be able to dissipate the cold air discharge.
Well yehhhh…..always best to set a tank for maximum distribution, in my 90′ long T-ranch I set mine smack dab in the middle of the house, that way it’s the same distance just about everywhere. Kitchen’s on one end, Bath 1 right over the tank (as well as master bedroom….slight “ugg” there) and master bath at far corner. Works fine. I would think everyone should know that any electric hot water tank no matter what style has no flue.
Why would you need to upgrade your service if you use a 240 unit. The higher voltage means lower amperage .
Higher voltage implies lower amperage only if wattage is held constant. IIRC, wattage for 240V water heaters is 4500w.
Aaron: In addition to what Tim said, the reason you might need to upgrade your service depends on whether you’re adding new electrical load or not. If you’re replacing an electric resistance water heater with a HPWH that has the same power, you’re fine. If you’re replacing a gas water heater with a 240V HPWH with strip heat, you’re adding a significant load.