Hot Water

Safety

Heat pumps only use electricity, so there is no danger of carbon monoxide poisoning or gas leaks that you can have with a gas water heater. They are as safe as an air conditioner.

Clean

If you supply your heat pump water heater with 100% renewable electricity then producing your hot water will generate no greenhouse gasses and no air pollution.

Thanks to our friends at Electrify Now - water heaters for allowing us to share the following content.

NOTE: Many federal tax credits and rebates from the Inflation Reduction Act have been cancelled by the Trump Administration at the end of 2025. Make sure the information you find online is current.

For more information see the video Heat Pump Water Heaters - Lowest Cost, Lowest Carbon Hot Water from Electrify Now and San Diego Learn

These videos cover heat pump water heaters available in 2024. Heat Pump Water Heater Buyers Guide and 2024 Top 7 Water Heaters Compared

HPWH.pdf

Things to think about

Can take longer to reheat than a gas or electric resistance water heater unless they have backup resistance heating elements. All 240 Volt, 30 Amp units have the backup heaters. Some 120 Volt units have smaller heaters, some have none. Can offset this by putting in a larger tank so you have more hot water to start with.
Require sufficient air in the room to extract heat from. Without any venting most require around 100 square feet of floor space, so a garage is fine but a closet or utility room may be too small unless they have louvers in the door. Most units can be fitted with ducts to bring in warmer air (or exhaust cooler air) from (to) another room.
Make more noise than a standard water heater (similar to a dishwasher). Check the decibel ratings on the unit before you buy.

120 Volt Models

The 120 Volt models were developed to make it easier to replace a gas water heater with a heat pump. They typically can plug into a 120 Volt, 15 Amp circuit that is also used by another appliance. This can avoid the need for an electrician to install a new circuit, saving money.

The main disadvantage of these models is they either have no backup resistance heating elements or have small backup heating elements that will take longer than the 240 Volt to reheat the tank if all of the hot water is used. Also, due to the lower UEF these versions are not eligible for some government incentives (e.g. Golden State Rebate $700 to $900).

There are two methods to avoid running out of hot water and having to wait for the longer reheat time.

Install a unit with a larger tank than the gas water heater you are removing. For example, if you are removing a 40 gallon gas water heater you should install a 60 gallon heat pump water heater.
Install with a thermostatic mixing valves on the output pipes. You set the hot water temperature in the tank to 150℉ and the mixing valve adds enough cold water to lower the actual output water temperature to the normal 120℉. The added cold water simulates having a larger tank.

A O Smith 120 Volt model

Rheem 120 Volt model

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