An HPWH needs roughly 700 cubic feet when installed.Photo by AO Smith
As countries look to lessen their carbon footprint and meet tough climate goals, all eyes are on the building sector. There has been a push by almost all levels of government for innovation in the industry for “greener” technology. Technology like hybrid electric water heaters combine two different and traditional forms of heating — electric and gas.
“A heat pump water heater (HPWH) is a standard electric water heater with a heat pump. However, instead of generating heat directly, hybrid electric water heaters use electricity to move heat from one place to another,” explained Karl Fernandes, senior product manager at Rheem.
Further, Fernandes explains, “Essentially, the hybrid electric heat pump works as a refrigerator but in reverse. While a refrigerator pulls heat from inside a box and sends it into the surrounding room, a stand-alone air-source heat pump water heater pulls heat from the surrounding air and transfers it, at a higher temperature, to heat water in a storage tank.”
The system is comprised of three main components, the heat pump (on top), external condenser coils (around the tank), and the tank and electric elements. “By using a fan, the heat pump evaporator can draw in ambient heat, any air above 35 degrees,” explains Gregg Holladay, the business development manager of specialty markets with Bradford White. “The refrigerant then absorbs the heat, and the compressor increases the temperature and pressure of the 134A refrigerant, amplifying the heat. Next, the heated refrigerant runs through the coils, heating the water through the tank.”
Holladay also adds that, “The heat pump is the first response for recovery as hot water is drawn from the tank, using only about 500 watts of power to replace the heat. If the tank is depleted, the heat pump may also activate and standard heating elements to recover faster, following each manufacturer’s proprietary sequence.”
An HPWH has four operating modes, “heat pump-only mode, hybrid mode, electric-only mode, and vacation,” said Patricia Kirchner, product implementation manager at A.O Smith.
Tankless options
Storage units have dominated the water heating market; they are a standard and reliable option for homeowners. This also remains true for the heat pump water heater market and the majority of products available on the market are storage-type heat pump water heaters.
But tankless-type heat pump water heaters have started to make their way into the market. “Our technology doesn’t store any water. Our heat pump absorbs heat from the air and stores the heat in our specially designed thermal battery. This battery has a heat exchanger inside. When the water flows through the heat exchanger, it gets heated to the desired temperature,” explains Sri Deivasigamani, CEO of Intellihot. A concern with tank-type water heaters is that the water is stagnant within the unit. This can be concerning if there is an abundant amount of bacteria growth within the storage tank. Although some manufacturers of tank-type units have developed innovations which feature protection to help prevent the growth of bacteria on the tank lining.
Tankless heat pump water heaters could be an alternative for homes and businesses looking to utilize more space. Photo by IntellihotBenefits
One of the main benefits of adopting a hybrid electric water heater is that they are considered more efficient than other water heaters, gas, oil, or standard heaters. According to NR Can, a hybrid electric water heater is up to four times more efficient and uses up to 70 per cent less energy, on average, than a standard electric water heater. Additionally, electric water heaters led the overall water heater market and accounted for 51.3 per cent of the revenue share in 2022, according to a report done by Research and Markets.
Additionally, because the technology uses electricity, “There are no direct emissions from the home, unlike gas or oil. HPWHs use roughly 3,000 less kWh than a standard electric tank,” adds Holladay. HPWHs can also provide homeowners with monthly savings as, “Compared to a conventional style water heater, where you’re paying for the fuel or electricity, the hybrid electric provides cost savings because it’s using air that’s already there around the water,” states Kirchner. She adds that homeowners can save hundreds of dollars annually using an HPWH compared to a standard electric water heater depending on a home’s usage.
Hybrid heat pump water heaters work as a refrigerator but in reverse to provide water heating.Holladay also adds that when using an HPWH, “You get about $3 in hot water for every $1 spent because moving heat costs less than creating heat and HPWHs do both.” He also adds that a 240v HPWH has roughly the same rating in hot water provided and recovery as standard electric water heaters, with 65 to 67-gallon first-hour delivery (50 gallons), 77-gallon first-hour delivery (65 gallons), and 87-gallon first-hour delivery (80 gallons).
The benefit of using a tankless heat pump water heater, according to Deivasigamani, is that overall, it provides clean and healthy water. “Additionally, our tankless heat pump uses CO2 refrigeration, making the technology environmentally friendly. CO2 has a GWP of one, which gives it a superior heat transfer characteristic compared to synthetic refrigerants. Plus, it provides higher heat carrying capacity.”
Deivasigamani also mentions that Intellihot’s tankless heat pump water heaters “are three times more efficient than resistance tanks. Compared to paying around $100 per month, ours will be around $33.”
Installation
As with most installations, the best practice for installing a hybrid electric heat pump water heater or any water heater, “should always be installed with local codes in mind,” said Fernandes. Additionally, when working with water, thermal expansion is something that should always be considered. “We’ve focused on making the installation straightforward so that a standard regular plumber can easily put this product in. If you’re just swapping out electric for electric, it’s a simple switch out, and it’s mostly just properly sizing the tank. The contractor doesn’t have to touch any refrigerant or compressor, as that’s covered by warranty.”
To best utilize HPWH technology, “Install them in places that provide or have excess heat, for example, your basement furnace room, garage, or laundry room,” says Holladay.
This U.S. Department of Energy schematic shows the major components of a typical heat pump water heater.Additionally, for installation jobs, the main difference when installing an HPWH compared to a standard electric is that “You have to adjust and account for the air space needed for the unit. An HPWH needs about 700 cubic feet or louvered door,” states Kirchner.
Holladay, Kirchner, and Fernandes all mentioned that installation costs for an HPWH system are typically on the higher end when you are fuel switching and running a 240v line, but “For this product, through the Greener Homes Federal Grant, there are incentives of $1,000,” adds Fernandes.
Regardless of which system a homeowner decides to use, the main thing any person should worry about is, “whether or not your HVAC or water heating system in a home or business is efficient and healthy. We spend most of our time indoors, breathing in air and drinking water. So, ask yourself whether you are making any compromises,” suggests Deivasigamani.