In the last year or so, Heat Pumps have gone from being little known outside of HVAC circles to becoming a key plank in the Inflation Reduction Act. Today’s heat pumps are vastly superior to those deployed decades ago, but one startup thinks there’s still ample room for innovation.Harvest Thermal isn’t tinkering with the heat pump itself, though. In fact, the company uses an off-the-shelf system in all of its installations. Rather, it has developed a small add-on about the size of two shoeboxes that allows the heat pump to run when electricity is cheapest and cleanest.The idea behind the company was hatched when co-founder and CEO Jane Melia was confronted with a dying gas furnace in her “creaky old home in Berkeley.”“There was no way I wanted to put gas in again,” said Melia, who had previously worked at a solar startup. The obvious answer was to replace it with a heat pump, but to fully rid her home of gas, she’d also have to replace the water heater. That meant two heat pumps running on-demand, a setup that felt inelegant to Melia, an engineer with a doctorate in fluid dynamics. If she wanted to run either when electricity was cheap or when solar power was plentiful, she’d have to buy a big battery to boot. “Who can afford that?”The company’s goal to drive down the cost of home electrification has netted it a $4 million early stage round led by Earth Foundry with participation from MUUS Climate Partners, Starshot Capital, and Portfolia, TechCrunch+ has exclusively learned.Melia and her co-founders “went to the drawing board,” she told TechCrunch+, and came up with a system that integrated a heat pump and a hot water storage tank with “some really, really good controls.”