You probably know this: your once hot shower suddenly becomes cold, which dampens your mood.
Maybe someone in your household took an extra shower, or you did a few too many loads of laundry. This is a classic case of supply not meeting demand. Michael Rigney believes he can predict when a household will need more hot water, and thus avoid cold showers without having to resort to expensive alternatives like tankless water heaters.
Rigney's quest began a few years ago when he started looking into water heating. What he saw “was really eye-opening,” Rigney said in a recent interview with TechCrunch.
The basic technology of most water heaters, whether gas or electric, has changed little in decades. They may be cheap to buy, but they are not cheap to run.
Heat pump water heaters have changed that for many homeowners, improving efficiency and lowering electric bills. But even there, “I saw tremendous room for improvement,” Rigney said.
He founded Cala Systems in Boston in 2020, just as heat pump water heaters were gaining traction. That shift, he said, “presented an entrepreneurial opportunity to build the best heat pump water heater.”
Water heaters are usually fairly simple devices: essentially, they consist of three basic parts: an insulated tank, a heating element, and a thermostat. Most people set the temperature once and then forget about it; on rare occasions, they might set it a little higher when overnight guests arrive. As hot water is drawn from the tank, it is replaced by cold water, lowering the temperature inside. When the temperature is low enough, the thermostat tells the heater to turn on.
“This is really outdated,” Rigney said. “In 2024, we can do better.”
Cala Systems' first product will be a 65-gallon heat pump water heater.Photo credits: Cala Systems
Cala Systems' water heater combines 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, such as weather forecasts and time-varying energy prices, and sends it to the water heater. That data is then analyzed on the device along with household-specific information, including water usage patterns, the temperature of incoming cold water and whether the home has solar panels. (Rigney said the company will never sell household data.)
By analyzing water usage patterns, the tank can predict when demand will spike and heat water in the most efficient way possible.
For example, if the weather forecast predicts a few sunny days and then a few cloudy days, Cala's algorithms might decide to superheat the tank during the day using power from the homeowner's solar panels. Then, when hot water is needed, it would be mixed with cold water to cool it to the appropriate temperature. This would allow the water heater to make the most of the excess solar energy, essentially turning the tank into a battery that stores energy for a cloudy day.
In other cases, when both weather and water demand are constant, Cala's water heater can slow down the compressor speed, increasing the time it takes to heat the tank, resulting in an increase in efficiency. “When you're heating water, if you slow down the compressor, you increase the efficiency of heat transfer by about 30%,” Rigney said. “That's a pretty significant impact.”
And what if guests come? Cala has built in a boost mode that can be activated on the tank or in an app.
Today, water heaters in the United States are almost equally powered by natural gas and electric resistance, with oil, propane, and heat pumps rounding out the offering. Water heating accounts for about 20% of the energy used by a typical American household, and heat pump water heaters significantly reduce that while reducing people's dependence on natural gas.
Although heat pump water heaters only make up a few percent of the market, their market share is growing rapidly, partly due to incentives under the Inflation Reduction Act. And although they are initially more expensive to install, they are cheaper in the long run because they can be operated more efficiently, leading to lower carbon emissions in the home.
Rigney said Cala will buy parts from various suppliers and assemble the final product in the U.S. (“This is not a product that ships well,” he said, laughing.) The company's first product, a 65-gallon model, will cost $2,850; it can be preordered and will ship early next year. That's about $800 more than competitors, but Rigney said lower utility bills should make up that difference over time.
To help launch, Cala told TechCrunch exclusively that it has raised $5.6 million in seed funding led by Clean Energy Venture Group and the Massachusetts Clean Energy Center, with participation from Burnt Island Ventures, CapeVista Capital and Leap Forward Ventures. With so few heat pump water heaters sold to date, “this is a category that is still very nascent,” Rigney said. “We believe there is an opportunity here to redefine what people expect from a water heater.”
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