Boiler / pump on and off every few minutes

I've just installed Tado smart thermostats and TRVs in our house.

When we are requesting heat in a room, the radiator does work and heat up as expected and go off at the right temperature, but while on, the boiler or boiler pump switches on and off every few minutes. I'm worried that this will lead to excessive wear and tear and ultimately failure over time.

Tado say: "Please note that your tado° will need a short period of time to adjust (normally a couple of weeks), so please observe it and let us know if there is still an issue then." They also confirm that the Tado devices are working as intended.

However, this problem doesn't seem to be going away. Any thoughts on how to fix it?

Thanks.

Answers

  • It sounds like your boiler may be SHORT CYCLING. How many radiators are requesting heat when the boiler is switching on and off?

    A modern boiler can modulate its gas burner to give less energy to the heat exchanger e.g. a 18KW boiler can turn itself down to 5KW. However, if you have a single radiator (usually less than 2KW) requesting heat it will obviously not be able to accept the excess energy and the water returning to the boiler will be too hot. The boiler will turn off the gas burner and wait for the water in the pipes to cool before it ignites again.

    If you don’t have a new boiler then there is no modulation and it is full power or nothing.

  • Hi that sounds like what's happening. Our boiler is a year old. It's usually when we have just 1 or 2 radiators requesting heat. Do you know if anything can be done about it?
  • Most boilers will short cycle as the house temperature approaches the set temperature and the heating load becomes too small for the heating source. But a boiler that does it too often may wear out prematurely. The only thing I can suggest is to group some of the TRVs so that multiple radiators are switched on at the same time. Not ideal, but it’s a common problem when zoning individual radiators with smart TRVs, regardless of the brand.

    Fortunately you have a new boiler so it should modulate its burner a lot better than the older ones.

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