This startup wants to turn your water heater into a smart thermal battery

Unless your shower turns cold, you probably don’t give much thought to your water heater. But it’s a major energy user in the home, and unlike solar panels or heat pumps, it’s gotten relatively little attention as a piece of smart home tech. A new startup is trying to change that. The company, called Reservoir, designed a heat pump water heater that predicts when you’ll need hot water and heats up in advance, when electricity is cheapest. The upfront cost is comparable to other water heaters,...