For years, if you wanted a heat pump water heater in the United States, there was basically one option: a big, tall unit that combined the compressor and the storage tank in one piece. That worked fine for most American homes with basements and garages. But for the millions of people living in apartments, condos, and manufactured homes, those bulky units simply didn't fit.
Now, that is starting to change. Split heat pump water heaters — where the compressor sits outdoors and the tank goes inside — are finally gaining traction in the U.S. market. After a decade of having just one model available, two new manufacturers launched split systems in the last year alone. And a competition is underway to spark even more innovation.
The Northwest Energy Efficiency Alliance (NEEA), a group that works to make homes more energy-efficient, estimates that more than 2 million homes each year could benefit from compact heat pump water heaters — if compact models existed at scale. "These are homes that can't fit today's big units," said a spokesperson for NEEA. "We're finally getting the products we need."
The first split heat pump water heater to hit the U.S. market was the SanCO2, which arrived in 2015. Consumer Reports ranked it the number one heat pump water heater for its efficiency and speed. But at $5,300, it costs much more than standard models, which often sell for under $2,000. That's a problem, because the homes that need compact units tend to be smaller and more affordable — and the families living there are often the ones who can least afford a high upfront price.
In the last year, two more manufacturers jumped into the market: Ecological, which makes a tall, skinny tank, and A. O. Smith, which offers several options including small low-profile tanks. NEEA's Hot Water Innovation Prize likely helped push these companies to act. The prize challenges manufacturers to build split systems that are both affordable and compact.
This August, judges will announce the winner of that competition at ACEEE's Summer Study, a big conference for energy efficiency experts. The winning design could lead to pilot programs and, eventually, mass production.
Heat pump water heaters are considered one of the easiest wins in home energy efficiency — they use far less electricity than traditional water heaters that rely on heating elements. With split models finally becoming available, families in all types of homes may soon be able to take advantage of the technology.