Modulating in relay mode

My tado thermostats are wired in relay to the boiler, a lot of the time the zones have 1 ‘wavey’ line and are calling for heat according to the app. The boiler doesn’t tend to start up when this happens which I’m fine with but it skews the boiler activity timings in the app.
Is there a way to prevent this?


  • johnbur
    @Danger8 I don't think that 1 'wavey line' contributes to the time in 'heating activity?
    For me, if I only have 1 'wavey line' showing in the app, the time does not go up. (or, it didn't when I thought the same...!)
  • @Danger8 I also have tado thermostat wired in relay mode to the boiler (2 wires). The thermostat also shows only 1 wavy line for most of the time. What I think is a problem is that the boiler turns on for like 2-3 minutes and then water pump runs for another 5 minutes and it turns off. Everything is turned off for 2-3 minutes and then boilers turns on again. This scenario repeats over and over again. I'm not really sure if this is good for the water pump. How does you boiler work with tado? Is it the same?

  • ValiE
    edited January 2022

    @andertl same happens to my boiler: it starts for around 16 sec and then it enters in a strange stage (maybe pump is re-circulating the hot water) for around 2 min and 52 sec, this happens for many times. Also it seems to try to modulate the power - that sin wave icon shows just one item

    Did you managed to solve the issue?

  • @ValiE Contact support. They are able to set minimum heating time and minimum time between two cycles. Default values are 180 seconds and 1200 seconds. I don't understand why this settings is not in the app. I had Netatmo previously and it was possible to set these parameters in the app.

  • Thanks @andertl , I already got in contact, or at least I hope Marie forwarded my complains to the technical team ... but still now reply from them.

  • rafm5
    rafm5 Volunteer Moderator
    edited December 2022

    @andertl and @ValiE - did you manage to get this sorted?

    What I'm seeing is, at 55°C the boiler works in 2 modes: 30 seconds heating + 2 minutes for water pump?

    That gives 50 on / off cycles per hour!

  • KBH

    Yes this is a major issue with the tado thermostats. I fitted a smart power plug to the power point of the boiler and it shows that it cycles on and off up to 8 times - this cannot be good for the SIME DGT30E. I wish there was a setting to just function ON and OFF without "wavy lines" like every other thermostat functions. I will replace it soon as the heater is close to the bedroom window and having it cycling drives us mad.