Heat Pump Water Heater FAQ

Basics

Heat pump water heaters use 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 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 a tanked gas water heater. The split systems consist of an indoor storage tank and an outside unit with a compressor (and associated equipment) that captures heat from the outside air. 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. Some types of HPWHs can function at temperatures below 0 degrees F.

Heat pump water heaters come with different tank 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. If you are switching from an electric water heater, a HPWH can reduce your water heating costs by up to 70%. If replacing a natural gas water heater, you will likely reduce your monthly water-heating costs, but the savings may not be substantial. Pairing the HPWH with a solar array can generate substantial savings when compared with a conventional natural gas water heater. Finally, if a gas water heater is replaced with a HPWH powered by clean electricity, the carbon footprint of the household is greatly reduced.

No. Tankless electric 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. HPWHs that use CO2 as a refrigerant can achieve even higher efficiencies.

Economics

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 will generally have lower operating costs, cutting your monthly bills right away. Numerous factors can affect the unit price, including geographic location, installation complexity, model selected, and contractor rates.

It depends on a number of factors, especially the electricity and gas prices in the area and the structures of the electricity and gas rates. YellowTin can help by estimating the savings based on your inputs.

Installation

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, to an indoor closet. 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 tank for 3 people or fewer and an 80 gallon tank for 4 or more people in the household.

Maintenance

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

Environment

It depends on the carbon intensity of the electricity used in the HPWH. In most of the US, a HPWH will have a lower carbon footprint than a gas water heater. If rooftop solar is used as the source of power, the carbon footprint of running a HPWH is drastically reduced.

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 allows 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 6-year or 10-year warranties on their products.