Heat pump water heaters

What is a heat pump water heater?

Heat pump water heaters (HPWH) operate at efficiency of 200% or more. A HPWH is equipped with a heat pump that transfers heat from the air into the water. By moving heat, rather than creating it, they can offer high efficiency.

Benefits of a heat pump water heater

A heat pump water heater:

• Operates with high efficiency.
• Provides cooling and dehumidifying in the space around the water heater.
• Provides flexibility between heat pump and traditional electric resistance when necessary.

Your trade-off is an increased initial cost and increased maintenance, due to heat pump water heaters including more mechanical parts. They also require more space to meet air flow requirements than a traditional tank water heater. HPWH can be noisier and are slower to heat up a tank of water. Additionally, heat pump water heaters are well suited for use in warmer climates. Because they draw heat from the air, they can place a higher demand on your central heating system during the winter.

Note: Many manufacturers do not recommend their heat pump water heaters be placed on an off-peak program where they’ll be subject to energy control.

How do they work?

HPWHs transfer heat from the air into the water itself. The process looks like this:

• An evaporator vaporizes a refrigerant.
• A fan moves the surrounding air, and the refrigerant absorbs the heat from the air.
• This heated refrigerant moves to the compressor, where pressure and temperature increase.
• Heated and compressed refrigerant runs through a condenser and transfers the heat to the water itself.

Most heat pump water heaters offer traditional electric resistance elements as a back-up heat source.