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Smart radiator thermostat

No wiring, no plumbing. Just thread it straight onto your steam radiator.

Start a pilotHow it works

Run a pilot and measure how much your building can save this heating season.

A white ARC unit threaded onto the brass valve of a white cast-iron radiator, a temperature lit on its display.

Smarter ways to save and stay comfy

  • 61% less radiator runtime1

  • Threads on in minutes6

  • No rooms running too hot

  • BACnet/IP for your BMS2

Adaptive heating

ARC intelligently holds the room temperature while people are there and turns the radiator down when they are not. Your old radiators start to seem almost alive — revived, you might say.

Charge that lasts the entire season

A swappable rechargeable battery that lasts the whole heating season, and refills over USB-C. No dangling wires, and nothing to replace mid-season.6

Up and running in minutes

Compatible with almost all US steam radiators, ARC threads easily onto existing radiator valves and shows up on the dashboard instantly.

The knob still works

Just like a thermostat. Turn the dial to adjust the temperature by hand, and the schedule takes over again once the room empties.

Interested in seeing them in your building?

Start a pilot with us now
From a peer-reviewed field study.10

Six months or moreon one charge6

Every unit's charge shows on the dashboard.

  1. 01

    Thread ARC onto the valve

  2. 02

    Plug in a gateway for the building

  3. 03

    See every room on the dashboard

72°F

Sample readout.

Watch ARC in action

ARC is intelligently tuned to give you the most comfort for the least energy.

A drawing of Room 214: a desk under the window, a chair, a plant, and a steam radiator with ARC on its valve.

Take control to walk into the room yourself.Move your cursor into the room to walk in.Tap the room to walk in or out.

Room 21410:00Day
Room
72°F
ARC
Holding
Energy use

The modeled day

A modeled room. The readouts are illustrative, not measured.4

Every room in one place

Monitor every room from the dashboard, or from your own BMS, and see how each one performs. Get real-time insights into consumption and cost.

The ARC dashboard on its Devices screen: every controller and gateway in the building on a row of its own, with the room it is in, the temperature there, the temperature it is set to, its battery, whether it is heating, whether it is online and when it was last heard from.The same list with one radiator opened out of it: the kitchen of a second-floor flat, 19.0° and rising to 20°, 15% battery, set to run on a schedule, with a panel giving its type, signal strength, firmware version and when it was last heard from.The same dashboard on its energy report for a heating season: a bar for each month from October to March, the months before ARC beside the months with it, over a row of sample figures for energy, cost and carbon.
Every radiator on one list, any one of them opened, and what a heating season saved. Sample values.

  • Built for steam

    Made to take the full heat of a North American steam radiator.

  • Peer-reviewed

    Rigorously tested in multiple field studies.1

  • Designed in the US

    Steamed up in the heart of Chicago.