Radbot Is a Robot for Rads That Could Reduce Heating Costs by 30 Percent

It's a smart thermostat for hydronic heating systems and is not such a dumb idea.

After we downsized and duplexed our house, the thermostat is in our apartment and the people upstairs constantly complain that they are too cold, especially now when it is seriously freezing out. That's why I have been thinking about the Radbot. I learned about it when I met inventor Damon Hart-Davis in London. It is a smart thermostatic valve for hydronic (hot water radiator) systems that are common in older houses like mine, and most houses in Europe.

Radbot in a box in London/ Lloyd Alter/CC BY 2.0Unlike conventional thermostatic valves, the Radbot reacts to more than just temperature but also changes in light levels. Vestemi claims energy savings of up to 30 percent. This seemed high to me, especially on hot water systems that have so much thermal lag, which is the time it takes for the radiator to start radiating. But these are not theoretical numbers; it has been tested. Hart-Davis explains how it learns through "probalistic predictive artificial intelligence," and deals with the lag:

If Radbot thinks you’re around now, you’ll get full target temperature. If Radbot thinks you might be, or will be soon, you get a small 1C or 2C temperature setback from the target implied by the dial position to save energy. No more than 3C if the room is light, but that is enough to get most of the target 30% savings. Radbot also looks ahead and tries to bring the room nearly to temperature in the hour before likely occupancy to minimise walking into a cold room. Maximum night setback is 6C.

Radbot/Screen capture

It also "computes and remembers a rolling 7-day notion of occupancy in 1-hour slots."

I have been dubious about smart thermostats and critical of smart vents, but having a smart thermostat on each radiator in each room makes a lot of sense, especially in a house like mine where the fancy new boiler is undersized and can't keep the house warm on really cold days like we are having right now (-8°F/-22°C yesterday). Turning off a rad doesn't cause the same kinds of problems of back pressure and distribution that turning off an air vent does. Sami has also demonstrated that smart thermostats can give you meaningful savings in leaky homes. Turning off the radiator in unoccupied rooms might make a difference, with radiators on only in rooms when people are using them.

I have also noted that smart thermostats work best in lousy buildings where the heating system is very busy; in super-insulated homes, the temperature doesn't drop very much and a smart thermostat would be bored stupid. But in the UK there are tens of thousands of leaky old houses and council flats (city-owned apartment buildings) where the boilers are always boiling and the radiators always radiating, with much of the heat being lost through leaky windows and uninsulated walls. This is where the Radbot could shine.

In a perfect world, all of those old buildings would get the Enegiesprong treatment, wrapped in insulation and new windows and not needing much heat at all, but as Sami notes, that costs about £85,000 per home. Smart thermostats like the Radbot are no substitute for insulation, but could make a real difference.

Sales Manager Dave Rose, CEO Jeremy Lock/ photo Lloyd Alter/CC BY 2.0

In the photo above, CEO Jeremy Lock and Sales Manager Dave Rose are out pitching the Radbot in London. More at Vestemi.com