Heat Pump Water Heaters

Intro/quick and dirty

I suspect most people probably don’t think about their hot water as much as I do. In fact most people don’t think about their hot water at all until they don’t have it anymore at which point the options are limited. If you have a garden-variety gas-powered tank water heater then you might consider replacing it BEFORE the tank fails and floods your house/basement. The good news is that now you can get a heat pump water heater that just plugs into the wall so no electrician needed. Rheem makes several options and I suggest getting the largest tank you can fit in your space and make sure the plumber installs a tempering valve so you can crank up the temperature to 140 degrees and then mix it back down to extend the amount of usable hot water.

What is a heat pump?

Your refrigerator is a heat pump! A heat pump just uses a law of physics that says that when a gas changes pressure, it must also change in temperature. This way you can “move” heat instead of creating it. If you also combine this phenomenon with variable speed DC inverter drive technology, you can create hot (or cold) air or water at efficiencies approaching 300 to 400% and higher.

Why get a heat pump?

Now that the world reached an agreement to phase out fossil fuels at COP28, house electrification will go from a fringe activity to mainstream to required. Heat pumps use electricity which can be generated with renewable means that help us achieve our critical climate goals. They also should save on utility bills since they use 1/3 to 1/4 or less as much energy as their gas counterparts.

Planning Ahead

If you have the luxury of planning ahead you can think more carefully about what you want and not be forced into a corner.

If you have a hydronic system now or you want one, it makes sense to get a heat pump system that can do BOTH space heating and domestic water heating
If you just want to heat domestic water then you might want to get a hybrid heat pump water heater that has a 30 Amp, 240 Volt circuit that can kick in if you need it (think teenagers back from college taking back to back showers!). These tend to come in 40, 50, 65, and 80 gallon versions and they require a general contractor or at least a plumber and an electrician.
Heat pumps make noise and cold air! An attached garage is a perfect place to put one but most older houses don’t have one. A basement could be a good location as long as it isn’t under a bedroom. A laundry porch could also work and worse case if you have to put it inside the house you can get your contractor to vent it into the attic so that it pulls hot air from the attic instead of from the living space.
If you really don’t want any noise or cold air problems, you can get a “split” model that has a tank that can go anywhere and an outdoor unit that goes outdoor and solves both noise and cold air problems.

Rebates/Tax Credits

As the Inflation Reduction Act rolls out it should be more clear what is available but because these rebates are income-dependent it is harder to say what is or isn’t available
Anyone should be able to take the 30% (max. $2,000) federal tax credit for a heat pump
Check for other available rebates (and contractors) here: https://switchison.org/

Contractors

Make sure you find a contractor with experience installing these as they take a bit more expertise than just a plumber typically has
In order to get some of the rebates, you have to use a contractor who is enrolled in the rebate program. Check here to see: https://switchison.org/

Brands

The three big names in American water heaters are Rheem, AO Smith, and Bradford White. I think Bradford White has higher quality standards but they don’t seem to offer plug-in units yet and are typically more expensive.

Tankless

Many people switched to tankless gas heaters for the obvious reasons of infinite hot water and space saving. If you really don’t have room for a tank you could consider getting an electric tankless water heater but they draw a TON of electricity and likely require you to upgrade your main panel to 200 Amps. If you have a small space like an ADU or you live alone and/or are careful about your water use, you could get away with a smaller on-demand electric water heater like the EcoSmart ECO 11 that only pulls 60 Amps and can handle a shower in our temperate climate. If you make sure not to shower when you run laundry then you’ll be fine

Optimizing

You don’t just have to settle for a single source of hot water. If you have a large house and/or the water heater is located far from where you use it, there a lot of other options you can employ to get a better experience and save water
Many companies make small tanks in 1, 2, 4, and 7 gallon sizes that mostly just plug into a normal outlet. We have a 4 gallon electric water heater under our kitchen sink and we all really love it because the hot water comes almost instantly. The 4 gallon tank is mostly right-sized for a dishwashing session especially if we use a dish pan. It does run out sometimes but then it only takes 20 minutes to refill.
It is really nice in the depth of winter to wash hands with warm water. Consider a small point of use electric on demand heater like an EcoSmart Eco 6. It is very small and can sit under a bathroom sink but it is powerful enough to make instant hot water for hand-washing. Alternatively you could do a smaller 1 or 2 gallon tank but these need to have pressure and temperature relief valves so not a great option for a bathroom on the 2nd floor.
If you are doing a major remodel or have a one story house and you are replacing old galvanized water pipes anyway, consider installing a hot water return line from the farthest water fixture from the water heater. Your plumber can throw a pump on top of the water heater with an adjustable timer so that you can recirculate the hot water in the morning and evening when most of the hot water is being used. This vastly reduces the wait time for hot water at all fixtures which saves water and time.

Bhima Sheridan