me with my hand showing thumbs down next to a heat pump water heater on the right side

You may be aware that heat pump water heaters are becoming a lot more popular these days. They can save a ton of energy versus older tankless or conventional tank units, but there are some potential downsides to watch out for.

I wanted to cover six downsides that may surprise you about heat pump (also called hybrid) hot water heaters, so I wanted to talk through these, and provide possible solutions for each one.

So let’s get right into it.

We’ve also got this topic as a full video on our YouTube channel. You can watch it here:

Downside #1: Lots of Moving Parts

The great thing about these heat pump units is that they save about 75% energy versus a conventional tank unit, but that comes with more moving parts.

Because these include all the components of a regular conventional tank unit and a heat pump system, that leads to potential for more parts breaking and higher potential maintenance over time.

Possible Solution to Having More Moving Parts:

Make sure the unit has a long warranty, and even a labor warranty component or reimbursement to it. Most heat pump water heaters come with a 10 year parts warranty, and a shorter labor warranty these days, but just make sure to check.

Downside #2: Cost Vs. Conventional Tank Water Heaters

Again, while these units save a lot of energy, they cost more initially vs. conventional tank hot water heaters. They can easily be 2-3 times more up front, which makes most people shy away from them.

Possible Solution to Higher Initial Cost:

Make sure to check your local city, county, and state rebates and tax credits. For instance, locally here in Denver, CO, Xcel Energy gives an $800 rebate when you install one of these.

Be sure to also check the federal heat pump tax credits for even more savings off the initial costs.

an conventional water heater energy usage chart versus heat pump water heater energy usage on the right side

Downside #3: Install Cost

These units install basically the same way as a conventional water heater, but there are a couple things to look out for.

Firstly, heat pumps have a condensate drain line that needs to be installed so that the water can drain out and away from the house. You do this either by draining with gravity or with a drain pump (but they aren’t too expensive.).

Depending on the heat pump unit and model itself, it may install a bit differently than a regular conventional tank, and installers may charge more for this, especially if they are not comfortable with heat pump water heaters next.

Possible Solution to Higher Install Costs:

Find an installer who is comfortable with these heat pump units, and be sure to get multiple quotes. I’ve installed these myself as a DIY’er and it wasn’t that bad at all. Besides the drain line, it pretty much installs exactly like a regular tank unit.

Downside #4: Required Space

While the heat pump water heater tank size is pretty much the same diameter as a regular unit, it’ll be a little taller to fit the heat pump on top.

Not only that, the manufacturers require a minimum amount of cubic air volume in the room, because these units take the heat out of the air and move it into the water in the tank.

You need enough air circulating in the space to provide enough heat for the water to get up to temperature, especially if you live in colder ambient climates.

Possible Solution to Air Volume Needed:

Install it in a larger room where the air is always at a decent ambient temperature, so the heat pump doesn’t have to work so hard.

This can be places like a crawlspace, large mechanical room in the basement, or if in a hotter climate, garage are perfect for them.

You can perhaps duct the inlet and outlet as well so that it vents outside all the time.

Downside #5: Noise

These are not silent like regular conventional tank units. The moving parts and fan on the heat pump itself do make some noise, like a quieter air conditioner.

I like to mention this because I was personally somewhat surprised by the noise when I turned these on for the first time.

The manufacturers know that noise can be an issue and the newer models are getting quieter through the years. I made a video of the noise on the popular big box brand hybrid water heaters also. You can watch that here.

Possible Solution to Noisy Heat Pump Water Heaters:

Install these in an area where people won’t be hanging out. Garages, basements, and mechanical closets or rooms away from bedrooms is ideal.

Even outside in a protected shed or cabinet of some sort could work well in warmer climates.

an energy savings chart showing the savings of heat pump water heaters at different kWh rates around the country

Downside #6: You May Run Out of Hot Water

Since heat pump water heaters take longer to heat up the water itself, if you undersize the tank size for your house and household needs, you might be left in the cold (literally).

They save much more energy, but they do take longer to heat up the water. Most units also come with the standard heating elements of a conventional tank unit, and these two components work together to heat up the water as fast as possible. But you want to make sure on this just in case.

Possible Solution to Undersized Tanks:

With HPWH’s, you can actually oversize the tank compared to your old one, and you’ll still save tons of energy. This can turn into more of a luxury. Be sure to account for all people in your household, and you can look up the flow rates and other factors to size it right for your own situation.

Personally, I bought the 40 and 50 gallon for our two netzero home renovations, and they worked great. But maybe go with a 65 or 80 gallon if you want to be cautious.


So while heat pump water heaters can be great, these are indeed some things to watch out for if you’re planning to install them.

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