How Quilt solved the heat pump’s biggest challenge

Smart home startup Quilt introduced a tri-zone heat pump on Tuesday that promises to maintain efficiency even in challenging conditions that hinder traditional occupants.

The three-zone unit does what it says on the label: one outdoor unit is now capable of powering three indoor heads, as they are known in the HVAC world. It’s a product that will make large installations simpler and cheaper while reducing its out-of-home footprint, and it’s key to the startup’s expansion plans, which were recently bolstered by a $20 million Series B focused on expanding sales.

But the real story is how Quilt developed the new product.

Since its founding, Quilt has prided itself on the amount of data it collects from its heat pumps. Not only are they connected to the Internet, but they are also equipped with more sensors than traditional heat pumps.

By analyzing that data, Quilt’s engineers were able to do things that other companies couldn’t. In September, for example, they shipped an over-the-air upgrade to heat pumps in people’s homes that unlocked an additional 20% capacity, which could be directed toward one or two zones. With the free update, people can feel more comfortable during heat and cold waves.

The team also used the data to develop the new three-zone module and, in the process, solved a nagging challenge faced by many competitors.

Like all heat pumps, multi-zone units work best when operated at variable speeds – that is, when heating or cooling demand is low, the compressor runs at a lower speed to provide only the amount of heating or cooling required.

But there are limits to how low their ability to function can be. Compressors become less stable at low speeds, making them more difficult to control. Matthew Noll, co-founder and CTO of Quilt, compares it to driving a car at low speeds. Maintaining a speed of 70 mph is easier than maintaining a constant speed of 11 mph. “It’s a little more difficult,” he said.

To compensate, most systems stop the compressor at some point, sacrificing some efficiency and comfort in the process.

However, Quilt was able to draw on data collected from about a thousand units already installed in people’s homes and businesses, giving them insight into how the systems work in the real world.

“The way most systems are developed is they’re tested in the lab under a couple of scenarios because testing is expensive. You end up with a product that’s kind of average,” Noll said.

“We have a thousand units in many different climates, and if we see something, we can look at it across a range of different units to understand whether there is room for improvement or whether we see a problem in a corner case,” he said.

The company also uses a larger copper coil than many competitors, allowing it to have smaller compressor specifications. This combination, along with a few other design modifications, allows Quilt to provide approximately 90% of its rated capacity (27,000 BTU) at -13°F (-25°C) without sacrificing low-demand performance or efficiency. Quilt says it’s the most efficient of the three zones on the market.

To save energy, each indoor head can be individually controlled, providing up to 2,210 BTUs of heat or 1,570 BTUs of cooling. If no heating or cooling is needed, refrigerant will still flow through the lines as in other heat pumps. But thanks to the outdoor unit’s low-speed performance, it only releases about 300 BTUs of heat in heating mode. This is equivalent to the same amount of heat lost as an adult.

Where does the quilt go from here? Knoll wouldn’t comment on future plans other than to say Quilt “wants to be able to have a solution for all homes.” There are more products to come, and large amounts of data will likely help drive their development.