Heat-pump water heaters just keep getting better

Industry Discussions Energy & Utilities
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Last November, Jonathan Cohen needed a new water heater for the house he and his wife had recently purchased.

The labor economist at Amazon was keen to get a heat-pump water heater, a superefficient electric technology that could save him money on his utility bills. Thorough by nature, he emailed 12 plumbers to ask how much it would cost to install Wirecutter’s top pick. He got few responses, none encouraging. Plumbers who were willing to install that model said the price would depend on an unknown quantity: subcontracted electrical work.

Cohen recoiled at the potential logistical nightmare. ​“You’re dealing with a plumber, and then they have to coordinate with an electrician, and they have to get separate quotes and pull the permits,” he explained. ​“I didn’t want to be a project manager.”

Then his brother-in-law told him about Reservoir, a new heat-pump water heater startup that has in-house tradespeople and competitive pricing that includes installation.

Why choose a heat-pump water heater?

Heat-pump water heaters are about three times as efficient as gas-fired or electric-resistance varieties, cut planet-warming emissions, and often lower monthly utility bills. Switching from a resistance system can save a household almost $23,000 over the appliance’s 15-year lifetime. Because they move heat instead of generating it, heat-pump water heaters act like air conditioners and can replace dehumidifiers, saving homes with muggy basements hundreds of dollars each summer.

But the tech has yet to take off. While Americans bought about 5 million electric water heaters in 2024, beating out the next most-popular option, gas-fired, only an estimated 214,000 were heat-pump water heaters, according to the decarbonization nonprofit New Buildings Institute.

“The biggest barrier is cost,” said Noah Gabriel, senior project manager at the institute. Consider the difference in two products from leading manufacturer Rheem: A 50-gallon heat-pump water heater has a list price of $1,699, while a highly rated electric-resistance model retails for just $799. The installation cost for a heat-pump version can be comparable to that for conventional systems, adding another $1,000 to $4,000 or more, depending on factors like tank size, a home’s electrical readiness, and local labor costs.

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OK, this is weird.

When we moved into our new-to-us but-with-a-previous-owner house about 6 years ago, I chose to replace the water heater. I bought a heat-pump version at the local Lowe’s (it cost more) and had it delivered.

It took exactly the same electrical connection (220v) as the old one, took exactly the same water connections as the old one (one in, one out, one pressure relief valve) and I changed it out myself in a few hours.

The biggest issue was getting it around the corner in the furnace room, past one of the household heat pumps that give us our A/C and winter heat.

There was literally nothing different about the install, except for downloading an app and connecting it to the “brain” of the unit.

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In many places, the new code requires all sorts of other things that add labor and cost to a HWH install. For example, many places require an overflow pan with a drain, that means that the pan has to be purchased ($20-30 at Grainger), placed onto the floor (or other surface), THEN the water heater has to be placed INTO the pan and centered (this is sometimes difficult because they’re pretty heavy), and then the plumbing for the drain from the pan has to be installed. Could add 2-3 hours of labor (at $150/hr that adds $300-$450 easily), add parts and miscellaneous and it’s quickly an extra $600-800 total. The emergency pressure valve has to be plumbed in many places as well. And there are also places (and I recommend EVERYONE should have) an automatic shutoff valve that is triggered by water somewhere near the bottom outside the tank (aka “a leak”). The high-end Rheem heat pump HWH comes with it, but for all others it has to be purchased separately ($192.58 list).

Before you know it, the complexity gets beyond the average DIY-er. So they pay $2k to have a relatively simple water heater installed. To me, $2000 is a ripoff for something so simple relatively, so I also DIY (get a son or SIL (or wife or daughter even) to help wrestle the thing across the garage and onto the pan). For my current HWH (heat pump of course, since 2015 or so) I installed flex connections for the supply and hot side to make the next install easier. I have a torch and I can do copper soldering, but why bother if I can avoid it.

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In no particular order: mine came with an auto shutoff wire that hangs down and sit on the floor. I did nothing except let gravity keep it there. It’s a little plastic box and the wire disappears into the “heat pump housing”, which sits atop the water tank. (The “heat pump” module about a foot to maybe 18” tall and sits exactly astride the tank.)

My pressure relief valve is plumbed. It was before, so I merely hooked up the same pipe. (I had to make a slight extension because of the different location, but that was trivial with Pex and a crimp ring.

I chose not to put a pan underneath, which would have been hard for me (alone) but if it was required I would have. I more or less “walked” it into final position anyway.

[Edit: OK, thinking about it here’s how I would have done it: Get a four pieces 2x4, maybe 6” long each. Put them on the floor and put one other longer piece (long enough to allow the pan to slide under, 30”?) atop them as a bridge. Nail them together. Now walk the WH over to the bridge, which you have in almost place for final position, tip the water heater up and onto the bridge. Slide the pan under. Tip the water heater back down into the pan, keeping it at an angle as you kick the bridge out of the way, set the water heater back in upright position. Done, except perhaps for centering.] There’s always a way! Being a solo handyman requires creative solutions. I think this one might work!

So it’s possible there could have been an extra half hour if nothing else changed, (and hour with my “pan install” but to call plumbers and not have them respond because “it’s a heat pump”? Weird.

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To me this is a fantastical number. Must be for a large (wasteful?) family.

My current summer time NG bill is about $15/mon for water heating, dryer and cooking.

Mike

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Sure, using NG. Making heat with electrical wires is wildly inefficient. But that’s what electric stoves, HWH, dryers and the like do.

It’s so bad that the electric utilities gave discounts to encourage people to be totally electric otherwise it would never price out. But they want to encourage consumption, so they subsidize on the backs of other rate payers.

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A heat pump water heater moves heat from the surrounding air into a water storage tank using a continuous four-step refrigeration cycle. [1, 2]

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Sure. It takes heat out of the air and puts it into the water. It returns (much) colder air to the room in the process. At first I was worried that being in the same small room with two other large heat-pumps (the household HVAC) it would make it harder for them to work. (I belatedly realized that being geothermal they pull their heat from water and return it to the nearby river.)

But I found a fun hack; I rerouted the cold “exhaust” from the hot water heater over into the next room, in which I have the batteries that charge from my solar panels. So they help keep the batteries cool, which is, uh, kinda cool.

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This is the way!

The best way to use residual heat pump energy (unwanted cooled air, or unwanted heated air) is to route it somewhere where it might be useful to you. Even non-heat pump systems can make some use of their residuals, for example, the hot outdoor coils of a traditional split system A/C could be routed through the coils of a traditional resistance hot water heater which makes the whole system more efficient overall.

I’m visiting one of my kids and family now and their clothes dryer has stopped heating (it’s a condensing dryer) and I’ve tried a few things to fix it, and the next step is to take it apart and check the electricals. Since I don’t have any of my tools with me (except for my metric hex wrench set), I can’t do much. So perhaps it is time to buy a new one. Looking at heat pump models. Anyone have any recommendations (AEG, Bosch, Midea, etc make them)?