Smart home startup Quilt thinks it has finally cracked the nastiest problem in residential heat pumps: how to keep multi-zone systems efficient when demand is low.
On Tuesday, the company unveiled a three-zone heat pump that lets a single outdoor unit drive three indoor "heads" — HVAC-speak for the wall-mounted units that actually move air. That matters because multi-zone installs tend to get big, messy, and expensive fast. Quilt’s approach cuts the outdoor footprint, simplifies installs and, crucially, promises to stay efficient in the same tricky conditions that trip up incumbents.
The launch comes on the heels of a $20 million Series B aimed squarely at expanding sales. But the more interesting story is how Quilt got here.
Turning heat pumps into data platforms
From day one, Quilt has treated every heat pump like a connected sensor platform. Its units are online by default and packed with more sensors than typical systems. That gives the company a live feed from the roughly thousand units already installed in homes and businesses.
That data isn’t just for monitoring. In September, Quilt shipped an over‑the‑air update that unlocked an additional 20% capacity on existing systems. Homeowners didn’t swap hardware. They just woke up to heat pumps that could push more heating or cooling into one or two zones when a heat wave or cold snap hit — for free.
The same telemetry is behind the new three-zone model.
The low-speed problem everyone hates
Like most modern systems, multi-zone heat pumps work best when they can run at variable speed. When a home only needs a little heating or cooling, the compressor should throttle down and sip power instead of cycling on and off.
That’s where things get ugly. Compressors become unstable at very low speeds, which makes them hard to control. Matthew Knoll, Quilt’s co-founder and CTO, compares it to driving: holding a steady 70 mph is much easier than keeping a car locked at 11 mph. “It’s a little harder,” he said.
Most manufacturers avoid that headache by shutting the compressor off once it drops below a certain speed. They protect the hardware, but they give up efficiency and some comfort along the way.
Quilt leaned on its field data instead.
“The way most systems are developed, they’re tested in a lab under a couple scenarios because testing’s expensive. And you end up with kind of a… average product,” Knoll said. “We have a thousand units out there in many different climates, and if we see something, we can look at it across a bunch of different units to understand if there’s room to optimize or if we’re seeing a problem in a corner case.”
Instead of designing around a handful of lab tests, Quilt tuned its controls against real-world behavior across climates and building types.
Bigger coil, smaller compressor
Quilt didn’t just lean on software. The hardware matters, too.
The company uses a larger copper coil than many competitors. That lets Quilt spec a smaller compressor without sacrificing output. In combination with other design tweaks, the system can deliver nearly 90% of its rated 27,000 BTU capacity even at −13 °F (−25 °C), while still performing efficiently at low demand.
Quilt says that makes this unit the most efficient three-zone mini‑split on the market.
Each indoor head can be controlled independently. On the low end, a single zone can dial heating down to 2,210 BTU or cooling to 1,570 BTU. That kind of fine-grained control is key if you only want to condition, say, a bedroom at night without over‑conditioning the rest of the house.
Even when no zone is actively calling for heat, refrigerant still circulates through the lines, just as it does in conventional systems. The difference is how little stray heat Quilt’s outdoor unit throws off at low speed. In heating mode, it releases only around 300 BTU — roughly as much as the body heat from a grown adult.
Where Quilt goes next
Knoll isn’t ready to talk specifics about the roadmap, beyond saying that Quilt “wants to be able to have a solution for all homes.” More products are coming, and the company is betting that the same mountain of performance data that shaped this three‑zone system will guide whatever comes next.
If Quilt is right, the next wave of heat pumps won’t just be efficient out of the box. They’ll keep getting better every winter and summer, one software update at a time.
