Heat Pump Water Heater FAQ


A heat pump water heater uses electricity to move heat from surrounding air to the tank water instead of heating the water directly. This process makes them three to four times more energy efficient than standard electric resistance water heaters and can cut water heating costs by up to 70%. Heat pump water heaters have a tank gallon capacity similar to standard models, with the same range of temperature adjustments.

Heat pump water heaters generally fall into two types or categories – integrated and split system models. Integrated systems are “drop-in” and have approximately the same form factor as tanked gas water heater. The split systems consist of an indoor storage tank and an outside unit with a fan for capturing the heat. They require additional plumbing between the indoor and outdoor unit.

An indoor unit can technically function in any climate but might increase space heating bills in winter as it draws heat from the conditioned space. Outdoor units function well above freezing temperatures. Come CO2 based units can function to temperatures of 5F.

Heat pump water heaters come in different sizes. The most common size currently on the market is 50 gallons. 65 and 80 gallon units are also available. Consumers replacing a standard electric water heater with a heat pump water heater of the same size should not notice a significant change in the amount of hot water available.

Heat pump water heaters use a proven energy-efficient technology to heat water for residential use. Switching to a heat pump water heater can reduce your electric water heating costs by up to 70%. In case of gas water heating there will be savings but they may not be substantial. Pairing the HPWH with a solar array can generate substantial savings over a tanked gas water heater. Finally if clean electricity used to run the HPWH, the carbon footprint of the household is greatly reduced over a gas water heater.

No. Tankless water heaters can be at most 100% efficient as they directly heat the water with electricity. A HPWH just moves heat and can be effectively 300-400% efficient. The efficiency rating can be obtained by multiplying the EF (Energy Factor) rating of the HPWH with 100.


The purchase price of a heat pump water heater is higher than the cost of a standard electric or gas water heater, but utility rebates, tax credits and promotions can significantly reduce the purchase price. Plus, the unit pays for itself by significantly reducing household energy use, saving you money almost instantly. Numerous factors can affect the unit price, including geographic location, installation complexity, model selected, and contractor rates.

It depends of the electricity rate used, the tier of electricity used and the gas rates of the area. YellowTin can make an accurate calculation on the savings based on your inputs.


For electric water heaters the process is mostly straightforward. The HPWH might be slightly taller to accommodate the heat pump on top. To switch from gas, an electrician needs to draw a 240V line from the main panel or a sub-panel to the installation point of HPWH. Also some condensate lines have to be added to drain out minor condensate from Heat Pump.

Heat pump water heaters can be installed in a variety of locations, from an unheated garage or basement to a heated utility room. The unit does make some noise with a fan and spews out cold air as it captures heat from its surroundings. The cold air, if undesirable, can be vented out using ducts. The split units have the fan outside the house but require additional plumbing to connect the indoor out outdoor units.

A normal rule of thumb is 50 gallon for 3 people or less, 65 gallon for 4, and 80 gallon for more than 4 people in the household.


Unlike standard electric water heaters, heat pump water heaters use an air filter that needs to be cleaned with water periodically to ensure efficient operation. Other maintenance needs are similar to those of standard electric or gas water heaters.


It depends on the carbon intensity of the electricity used in the HPWH? In California almost in all areas the HPWH will have a lower carbon footprint than a gas water heater. If rooftop solar is used the carbon footprint of running it is essentially zero.

Steps to use

Heat pump water heaters are more interactive than standard electric water heaters. Most heat pump water heater models feature a control panel that allow homeowners to select water temperature and operation mode. Some are even WiFi connected and come with a Smartphone app. The app lets the consumer control the HPWH and examine energy consumption patterns which can then be used to optimize the usage.

Major manufacturers of heat pump water heaters typically offer 10-year warranties on their products. Please contact your heat pump water heater’s manufacturer for more details.


Silicon Valley Clean Energy (SVCE) offers rebates to customers to switch from a natural gas water heater to an electric Heat Pump Water Heater. Income-qualified households will be eligible for additional incentives. You must live in the respective CCE territory to qualify.