When choosing the right size heat pump water heater, you want to consider how many people are in your household and how much water they typically use at the same time (for example, back-to-back morning showers).

*Tank sizing recommendation is based on a 240-volt heat pump water heater
**Assumes roughly 8-minute showers using 17.2 gallons of hot water

If your household uses a lot of hot water, your contractor may recommend a larger tank size so that your water heater relies more on the highly efficient heat pump, rather than the electric resistance, to maximize your energy savings.

The optimal size should provide your household with enough hot water to make it through your highest period of water usage, including for showers and baths, shaving, hand washing, food preparation, dishwashing and clothes washing. A qualified plumbing and heating contractor with experience in heat pump water heaters can help you choose the best size for your home.

The U.S. Department of Energy provides a worksheet for estimating your maximum one-hour water usage to help with equipment sizing.  

Heat pump water heaters also need ample air space to work well. Basements can be an ideal location for a heat pump water heater. If you’re locating your heat pump water heater in a smaller space, like a utility closet, you may need to provide extra air by using things like a louvered door or wall grates to pull in air from an adjacent room, or by ducting it into another space. Be sure to talk with your plumbing and heating contractor about the space and ceiling clearance needed and consider any applicable building codes for your area.

If you are upgrading to a heat pump water heater, you should assess your panel size. You may need an electric panel upgrade, particularly if you are upgrading from a natural gas water heater to a 240-volt heat pump water heater. You can follow this guidance to determine your panel size or talk with a licensed electrician if you are unsure if you need an upgrade. With new advancements in low-voltage appliances (such as 120-volt heat pump water heaters) and load-sharing devices, there may be ways that you can manage your electric use without the need for an electric panel upgrade. See the Resources and FAQs page for more information on this.

Heat pump water heaters generate a small amount of sound (about as much as a dishwasher) and also generate cool air, so they’re better suited to basements, garages, interior rooms or sheds and utility closets, rather than living spaces.  

Heat pump water heaters produce a small amount of pure water condensate that must be plumbed to a sink or drain. If your water heater is near a clothes washer or furnace, you likely will have water drainage or a water pump nearby.