Heat pump hot water heaters, also known as hybrid hot water heaters, are the most energy-efficient type of water heater available on the market.
A heat pump water heater (HPWH) is a type of water heating system that operates by transferring heat from the surrounding air or ground into a tank or reservoir of water, raising its temperature for domestic hot water use. It’s an energy-efficient alternative to traditional electric or gas water heaters because it doesn’t directly generate heat but instead moves existing heat from one place to another using a refrigeration cycle, similar to how an air conditioner or refrigerator works but in reverse.
Here’s how a heat pump water heater typically works:
- Heat Absorption: The system consists of a heat pump unit and a storage tank for water. The heat pump unit contains a refrigerant that circulates through coils or pipes. This unit is placed in a location where it can access a heat source, such as the air in a room, outdoor air, or even the ground (geothermal heat pumps).
- Heat Extraction: The heat pump absorbs heat from the source, which can be the ambient air, by evaporating the refrigerant. This heat transfer process is energy-efficient because it doesn’t require the direct consumption of fuel or electrical resistance heating.
- Heat Compression: The absorbed heat is then compressed, which increases its temperature significantly. This high-temperature heat is then transferred to a coil or heat exchanger within the water storage tank.
- Heat Transfer to Water: The heat exchanger releases the heat into the water in the tank, raising its temperature. The heated water is stored until it’s needed for domestic hot water purposes, such as showers, washing dishes, or laundry.
Heat pump water heaters are known for their energy efficiency, typically delivering 2 to 3 times more energy in the form of hot water than the electricity they consume. They are particularly effective in moderate to warm climates, where there is a readily available source of heat in the ambient air. However, their efficiency can decrease in very cold climates because they have to work harder to extract heat from frigid air.
It’s important to note that heat pump water heaters may have a higher upfront cost compared to conventional water heaters, but the potential energy savings over time can offset this initial investment. Additionally, they help reduce greenhouse gas emissions because they rely on electricity and heat transfer rather than burning fossil fuels directly to heat water.
Why is it important to electrify my home?
Electrification is a vital solution to combat climate change. Using fossil fuels inside buildings for cooking, space heating, and water heating is responsible for up to 40% of greenhouse gas emissions. Gas water heaters are the equivalent of having another gas-powered car. We must reduce these emissions to mitigate further climate change. When combined with renewable sources of energy, a fully electrified home can operate with zero emissions.
Choosing a heat pump water heater is one of the most impactful choices you can make for the environment. If you have to buy another gas pump water heater, you’re locking in another ten years of harmful emissions. This also involves missing out on rebates and the health benefits associated with eliminating gas from your home.
Do I need to switch if I have a tankless water heater?
Although gas-powered tankless water heaters can be more efficient than regular gas tank water heaters, they still rely on fossil fuels, namely natural gas, for water heating. Not storing a huge amount of water doesn’t make a difference if it’s still being powered by fossil fuels. Gas tankless water heaters also release a surprising amount of unburned methane — a global warming gas that’s 80 times worse for the climate than carbon dioxide! If you truly want to make a climate-friendly choice for water heating, heat pump water heaters are the way to go.
Are there any tax credits for heat pump water heaters?
Yes, under the Inflation Reduction Act, the federal government is offering a tax credit of 30% of your project cost up to $2,000. This counts for any ENERGY STAR qualifying heat pump water heater.
How does transitioning to electric water heating affect my energy bills?
Once you switch to a heat pump water heater, you will consume approximately half the energy required to heat your water compared to using gas.
According to Department of Energy researchers, “Heat pumps function like a reverse refrigerator. A refrigerator removes heat from an enclosed space and releases it into the surrounding room. A stand-alone air-source heat pump water heater extracts heat from the surrounding air and transfers it, at a higher temperature, into a tank to heat the water.”
Most modern heat pump water heaters are equipped with an additional electric resistance heater as a backup in case the surrounding air temperature is too cold. This is why they are often called hybrid water heaters, combining both a heat pump and electric resistance.
For optimal performance, heat pump water heaters should be installed in an area of your home that maintains a year-round temperature range of 40º–90ºF (4.4º–32.2ºC). Suitable locations include mechanical rooms, garages, crawl spaces, or unfinished basements. Additionally, these water heaters require approximately 700 cubic feet (28.3 cubic meters) of air space around them to function efficiently.
Energy consumption/usage: The monthly or yearly energy usage of the heat pump affects the operating cost. The average heat pump water heater consumes approximately 1,000 kWh per year. Larger tanks generally require more energy.
Choosing the Right Heat Pump Water Heater
When choosing the right heat pump water heater (HPWH) for your home, it’s important to consider the brand, size, and specific hot water usage requirements. Here are some factors to consider:
The most common HPWH sizes are 50 gallons, 65 gallons, and 80 gallons. The following sizes work best based on the number of family members:
- 50 gallons: Suitable for families of 3-4
- 65 gallons: Recommended for families of 4-5
- 80 gallons: Suitable for families of 5 or more
However, it’s essential to consider your specific hot water usage patterns. If you frequently use large amounts of hot water, such as for big baths or when hosting guests, it might be beneficial to size up. This may come with a higher cost upfront but can provide peace of mind.
We also recommend using a Thermostatic Mixing Valve (TMV). This valve allows you to store more hot water than you use since it mixes hot water from the tank with enough cold water to achieve the desired temperature. This feature can reduce hot water consumption by approximately 15% for each shower, dishwasher, or other hot water usage.