The Boldr Kelvin is unlike other space heaters I've tested. It is a blank mirrored panel, 3 feet across on its longest side, meant to hang on a wall. It comes in any color you want, as long as it's white or black.
The Kelvin looks a bit like a TV without a border, or the monolith in Stanley Kubrick's 2001: A Space Odyssey. Instead of driving apes crazy, this particular monolith emits far-infrared heat (a type of radiant energy) that its maker promises will make me feel toasty-warm while consuming a fraction of the power of a standard heater. Unlike resistance heaters with fans, it's blessedly silent. And there's an app that tracks basically everything, from room temp to energy use.
In the usually hype-free world of space heaters, a trail of influencers and review outlets have hailed the $400 flagship device from Boldr—an international tech startup incorporated in London and with founders in Lithuania and Brazil—as the “smartest heater you'll ever own,” a piece of “modern wall art” that makes traditional heaters seem obsolete, and a “seriously great” solution to your house's one cold room.
While it's certainly the most interesting heater to pass my desk in the past year, I've had a much more troubled relationship with the Kelvin. This has been true since I tested the first-generation device last spring. Boldr's app remains a work in progress, the heater's use case is narrow, and the panel kicks a surprising amount of heat back to the wall you hang it on.
Red Heat
Photograph: Matthew Korfhage
The Kelvin's biggest selling point is that it can save you energy by using far-infrared heat, a part of the non-visible spectrum that humans are thought to perceive primarily as warmth. Far-infrared has been a subject of great interest lately as a potential treatment for conditions as diverse as cancer, cardiovascular disorders, diabetes, and arthritis.