Five years ago, while working at Apple as a product designer, Mary Ann Rau decided to electrify her house and move away from fossil fuels. She installed solar, a battery, an induction range, and owned an EV. But there was still one big challenge: her HVAC system. “When it came to heat pumps, I was shocked when I got a quote for $40,000 to install heat pumps in my own house,” Rau says.
Today, Rau launched a startup that’s tackling the problem of making heat pumps more accessible. Merino Energy, which just came out of stealth, makes heat pumps that each take an hour or less to install and come with a fixed price per unit of $3,800, including installation fees. For a whole home, the system could be half the cost of a typical mini split installation. (For someone who wants to add a unit to a single room, it’s an even bigger difference, coming in at a third of the cost.)
Rau left Apple in 2023 and first worked at Quilt, another startup designing sleek mini-split heat pumps. There, she learned about the complexity of installation, a major driver of cost. “I learned that that was really the true bottleneck when it comes to heat pump adoption,” she says. Mini split heat pumps—units that are installed in walls in rooms throughout a house, and then connected to a condenser outside—can each take eight hours to install. Skilled technicians have to add refrigerant to long lines between the mini splits and the condenser. Labor for the whole process is expensive.
New window heat pumps are faster to install, but aren’t compatible with some windows. (Rau’s cofounder, Brad Hall, previously worked at Gradient, one of the companies pioneering window heat pumps, but couldn’t install the product at his own home.) They saw an opportunity to design a different alternative.
Merino’s design eliminates outdoor units and the need for complicated connections. Instead, it uses two vents in the wall, one to pull air in and one for exhaust. Each unit takes around an hour to install, shrinking the overall cost. Because refrigerant is added at the factory and not on site, that also reduces labor. Adding refrigerant at the factory also means there’s little risk of it leaking; small leaks can be a major source of emissions. “One leaky mini split can erase the benefits of transitioning around 50 homes off of fossil fuels,” Rau says.
The team worked closely with installers to understand what needed to change. Part of the challenge with existing heat pumps wasn’t just the installation time, but the fact that HVAC companies were spending valuable hours visiting homes to give quotes that homeowners ultimately couldn’t afford. By offering flat rate pricing, homeowners can decide beforehand if they want to move forward. The approach means that Merino can give installers better margins while still saving homeowners money.
The team also carefully considered the product design. “It’s designed to blend into your home like a modern artifact,” says Rau, who worked on AirPod design at Apple. The heat pump is quiet as it runs, and relatively sleek at 7.8 inches deep, “so it doesn’t take up too much space visually in the room,” she says.
It also integrates with smart home tech like Apple HomeKit and Google Home, as well as wearables like the Oura Ring. “There are clinical studies that show that you can improve sleep quality and sleep efficiency by reducing temperature by several degrees when you’re in REM,” Rau says. “So if you choose to integrate your Oura Ring with our product, then you will get the benefit of automatic temperature control based off of your sleep cycle.”
The company is launching first in California, where there’s strong demand for heat pumps. Los Angeles recently passed a rule requiring landlords to keep indoor temperatures below 82 degrees as extreme heat becomes more common. Many apartments in L.A. still lack air conditioning, making the new tech a relatively affordable way to add it permanently. Merino also makes a simplified version for low-income housing and recently installed it in a Bay Area apartment building for formerly homeless residents
The state also has an aggressive goal to install six million heat pumps by 2030. “At the current pace of installation, it would take until 2045 for California to hit its goals,” Rau says. “With Merino, we think that we can actually do it in four years, and that’s because we’re doing installation eight times faster.”
The startup opened preorders on its website today, and expects to ship the first products in late 2026.