Boldr Kelvin Review (2026): Heats Your Body, Heats the Wall

Company co-founder and CEO Maddy Ablyazov told WIRED in a video interview last April that he sees the heater as just one part of an energy management platform that will allow homeowners to track energy use and costs across devices as diverse as heat pumps and solar panels. Boulder is, at heart, a tech startup with a space heater.

The Wi-Fi- and Bluetooth-connected Boulder app tracks energy use over time, potentially across multiple devices and multiple rooms. Temperature and humidity are measured by one of several external thermostats, including a Clima Smart Controller ($165) that can ideally sync with other heat pumps or AC units in your home.

However, the app is still a work in progress, and has changed dramatically in the last year. Like most smart-home devices I’ve tested, it took a little trial and error before I decided Boulder’s devices would play nice with my router. This is a known difficulty with all 2.4-GHz smart-home devices, whether meat probes or security cameras. Still, the Boulder app needed more work than some.

Some of Boulder’s tools are glitchy, including an AI-guided feature designed to track and estimate energy costs. Boulder’s app quoted an absolutely indifferent 10 cents per kilowatt-hour for my Portland, Oregon, residence — a rate my city hasn’t seen since 2020. Adjusting Boulder’s app to the current rate also wasn’t as easy as typing in the rate that appeared on my energy bill. I had to jury-rig a solution that involved math. Booooo, math.

Other tools work more successfully. I can set the Boulder’s thermostat to lower the temperature at local sunset each day and raise the temperature at sunrise or at a specific time of my choice. I can also set the Kelvin to turn on when the temperature in a given room drops below a specific temperature or when the humidity reaches a set level. Alexa and Siri can also be integrated for those who prefer to chat from their devices.

If I want to give the device (and Boulder) access to my location, I can even set the desired temperature based on whether I’m home or not. I verified it was working, then turned off location tracking. I guess you trust who you trust.

I expect Boulder’s energy management system to continue to evolve. And there is reason for optimism: it will be a useful device along with other heating devices. But caveats add up. And I doubt I’ll use it with Kelvin.

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