You've probably experienced it: Your previously hot shower suddenly turns cold, leaving you feeling depressed.
Maybe someone in the family took an extra shower or did a few extra loads of laundry. It's a classic example of supply not keeping up with demand. Michael Rigney thinks it might be possible to predict when your home will need more hot water and eliminate cold showers, without having to rely on expensive alternatives like on-demand water heaters.
Rigney's quest began a few years ago when he started researching water heaters, and what he saw was “really eye-opening,” Rigney told TechCrunch in a recent interview.
The basic technology of most water heaters, whether gas or electric, has not changed much in recent decades, and while they may be cheap to buy, they are not cheap to operate.
Heat pump water heaters are starting to change the game for many homeowners by improving efficiency and lowering utility bills, but even there, “I felt there was a lot of room for improvement,” Rigney says.
He founded Kara Systems in Boston in 2020, a year when heat-pump water heaters were just starting to become popular. Because of that change, he said, “I saw an opportunity to start a company to make the best heat-pump water heaters.”
Water heaters are relatively simple appliances. They essentially consist of three basic parts: an insulated tank, a heating element, and a thermostat. Most people set the temperature once and forget it. On the rare occasion that they have guests over, they might set the temperature a little higher. As hot water is drawn from the tank, it is replaced with cold water, lowering the temperature inside. When the temperature gets low enough, the thermostat tells the heater to turn on.
“This is really outdated,” Rigney said. “We can do better by 2024.”
Cala Systems' first product is a 65-gallon heat pump water heater. Image courtesy of Cala Systems
Cara Systems' water heaters combine an advanced heat pump with an AI-powered control system to predict hot water demand and heat the water in the tank accordingly. The company collects general information like weather forecasts and energy prices by time of day and sends it to the water heater. That data is then analyzed on the device along with home-specific information like water-usage patterns, the temperature of the incoming cold water, and whether the home has solar panels. (Rigney said the company never sells home data.)
By analysing your water usage patterns, the tank can predict when demand will spike and heat your water in the most efficient way possible.
For example, if the weather forecast predicts a few days of sunshine followed by a few cloudy days, Cala's algorithms may decide to use daytime power from a homeowner's solar panels to heat the tank. Then, when hot water is needed, it mixes it with cold water to cool it down to the right temperature. This allows the water heater to make the most of excess solar power, essentially turning the tank into a battery that stores energy for cloudy days.
Other times, if the weather and water demand remain constant, Kara's water heaters can slow down the compressor speed to increase the time it takes to heat the tank and increase efficiency. “In hot water, slowing down the compressor speed makes the heat transfer about 30 percent more efficient,” Rigney says. “That can have a pretty significant impact.”
What if you have guests over at home? Cala now features a boost mode that can be activated on the tank or via the app.
Currently, water heaters in the U.S. are roughly split between natural gas and electric resistance, with oil, propane, and heat pumps remaining. Hot water accounts for about 20% of a typical U.S. home's energy use, and heat pump water heaters would significantly reduce this while also reducing people's reliance on natural gas.
Heat pumps may only make up a small percentage of the market, but their share is growing rapidly, thanks in part to incentives from the Anti-Inflation Act, and while they are expensive up front, they cost less in the long run because they are more efficient to operate and reduce a home's carbon footprint.
Rigney said Kara plans to buy parts from a variety of suppliers and assemble the final product in the U.S. (“It's not an easy product to ship,” he laughed.) The company's first product, a 65-gallon model, costs $2,850 and is available for preorder, with deliveries expected early next year. That's about $800 more than competitors, but Rigney said the difference will eventually disappear as energy costs fall.
To support the rollout, Cala told TechCrunch exclusively that it has raised a $5.6 million seed round led by Clean Energy Venture Group and Massachusetts Clean Energy Center, with participation from Burnt Island Ventures, CapeVista Capital and Leap Forward Ventures. To date, there have been very few heat pump water heaters sold, so “this is really a nascent space,” Rigney says. “We see an opportunity here to redefine what people expect from a water heater.”