heating confusion.

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I have quite the jankie set up. Tado TRVs on all heaters and a nest 3 thermostat. I have a fairly new boiler from intergas with open therm capability. The nest heating control is wired to the boiler. Can anyone explain why each TRV can trigger the boiler and call for heat despite nest and Tado not being compatible? Discovered it the hard way when my baby learned to crawl and turned on a heater (child lock is on now). For clarity - Nest connected to boiler, nest thermostat not calling for heat. Tado TRV overrides this and successfully calls for heat. No Tado Smart thermostat installed.

Answers

  • davidlyall
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    I think your system set up is possibly too obscure for comment on here.

    You'll probably need to enlist and installer who has experience of both Tado and Nest to make sense of what's going on

  • johnnyp78
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    I don’t see any way that this can be happening unless a) the nest can communicate with Tado trvs or b) the intergas boiler can. Both of these seem fairly unlikely - have you tried calling for heat from all your trvs? Does the nest register any activity when you do? Or does the boiler? You might be able to see what’s going on if the boiler has a menu screen.
  • I agree with you, i cant work out how this is happening. The nest doesnt react at all. The boiler is always on standby and it fires up as soon as the TRV calls for heat. Seems to bypass the nest altogether. Given Tado use their own communication protocol it should be impossible for the TRV to command the NEST heat controller. I even issued thew command through home assistant to see if the logs recorded any reaction from Nest and nope.

  • johnnyp78
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    Ok, I've done a bit of digging - is your Intergas model an Eco RF or Xclusive? They come with a built in radio transmitter which is compatible with Honeywell controllers like the DT92, which operates at a frequency of 868mhz, as do the Tado TRVs. Looks you've bypassed the extension kit, though no idea whether it's telling the boiler simply to turn off and on or whether it's telling it to modulate its output.

  • You sir are a genius. Thank you. My headache can finally be cured
  • johnnyp78
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    I wonder if Intergas or Tado are aware of it? Would save a bit of cash (and time wiring) if you could just buy Tado TRVs that will work with their boilers, without the wireless receiver, though I'd be interested to see if the TRV is telling the boiler to modulate its output. As they're opentherm compatible it might well be.

  • The other thing I wonder is how the boiler would distinguish between different systems. EG if my neighbor had them in their house would it trigger my boiler? For me its not an issue, my nearest neighbor is 30 meters away but if your in a block of flats, what's to stop it?

  • johnnyp78
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    It looks like they’re supposed to be paired first so yes, could be an issue if they work without doing that.