A heat pump water heater works like a refrigerator in reverse. Instead of using a compressor to pull heat from inside the refrigerator and transferring it to the surrounding room, a heat pump uses the compressor to take heat from the surrounding air and transfers it inside a storage tank, where your water is heated.

Most heat pump water heaters also have backup resistance elements – like a standard water heater – for situations when the ambient temperature in the room is not high enough. For most efficient operation, most heat pump water heaters are suited for a year-round temperature range of 40 – 90 degrees F.

For northern regions that have slightly colder temperatures, we recommend using the Northwest Energy Efficiency Alliance’s (NEEA) Northern Climate Qualified Heat Pump Water Heaters list as a guide to choosing a heat pump water heater that will suit your needs.

When selecting a heat pump water heater, you should consider the following:

1. What size and first hour rating do I need?
   Consider the number of bedrooms and bathrooms you have in your house, and ask your installing contractor to suggest a size that will fit your needs. Most heat pump water heaters will have a capacity of 50, 66, or 80 gallons, and the first hour rating – a measurement of how much hot water the heater will put out in an hour of operation – will only be slightly higher than the capacity, because the heat pump heating process is fairly slow.
2. What space constraints do I have?
   As heat pump water heaters are often taller and wider than the current model in your home, you need to consider the space available for a larger unit. Ask your installer to guide you through the process to determine if you have enough space to have the unit installed and to service the air filter.
3. What should I look for in an Efficiency Factor (EF)?
   The higher the EF, the lower the operating costs. The best heat pump water heaters have an EF of 2.0, which means that they are 200% efficient. While that might sound strange, the EF is comparing the amount of hot water produced per unit of electricity consumed in a typical day, so 200% efficiency means the heat energy produced is twice the amount of electricity consumed.
4. What brand should I select?
   Some important things to consider when choosing the brand of your heat pump water heater are warranty, availability of local service providers, and reliability. The best heat pump water heaters on the market have a lifetime warranty on the tanks, which are constructed with stainless steel.

   Make sure there are installers in your area who are certified to work on this product, in case you need to have your water heater serviced. Also, read up on what others who have bought the brands you have in mind have to say about their water heaters’ reliability.

Many utility companies offer significant incentives to help bring down the upfront cost of purchasing and installing a heat pump water heater. Call your utility company to find out about incentives available in your area.