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Boiler safety checks with smart radiator valves

I’m based in the UK and have a set up that consists of Tado smart radiator valves on each radiator and 2 Tado Wired Thermostats on ground and first floor that act as zone controllers for the radiator valves.

Last night I noticed that the boiler was firing even though all smart radiator valves were closed and the app was showing that no rooms were heating. After running checks on the system I discovered that it was the zone controllers on the first floor that was calling for heat while it shouldn’t have.

To solve the issue I increased the temperature in one of the rooms served by this zone controller, waited for a few minutes and then brought the temperature back. The relay in thermostat clicked this time and the boiler stopped. (Forum search has shown that a stuck relay is an issue that was experienced by other users as well)

Although my heating system has a bypass valve that the hot water would go through if all radiators are closed, this situation is still undesirable as the boiler runs unnecessary for long period of time circulating hot water through a very short loop.

It is totally preventable if Tado could implement the following integrity checks into the system.

  1. If a zone controller is off and one of the rooms starts heating make sure that radiator valve opens first, Tado gets confirmation that it is open and only then the zone controller calls for heat
  2. While zone controller is calling for heat do periodic checks that at least one radiator valve in the zone is open. If the check fails then stop calling for heat.
  3. When a room needs to stop heating and there are no other open radiator valves in the zone, make sure that the zone controller stops calling for heat, wait a few minutes to allow the boiler some time to stop the pump and only then close that last radiator valve in the zone.

Having these checks in place will greatly improve the reliability of systems where all radiators are equipped with smart valves.

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