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Help with what hardware/setup to have



Here's my current setup:

1x combi boiler

2x wireless thermostat (Honeywell CM927) with their 2 receivers connected to a single control unit

2x motorised valve

2 zones (one with all radiators, one for underfloor heating in the Kitchen)

4x bedroom radiators

2x bathroom radiators

My boiler is in a cupboard on the first floor so I can't have a wired thermostat connected to it.

My main goal is to be able to control each bedroom individually, a nice to have would be to control also the underfloor heating.

My understanding is that with 4 TRV and a wireless thermostat I can achieve my main goal, but for the underfloor heating I would need a wired thermostat (which I can't have).

I don't really care about changing the existing system for the underfloor heating, but I understand that I might not be able to combine Tado + Honeywell.

My questions are:

  • Can I connect a tado wireless thermostat/receiver to the existing Honeywell control unit? If not I'm assuming I will need to replace the Honeywell control unit by the Tado receiver
  • If I have to replace the Honeywell control unit by the Tado receiver, can I also have a wired thermostat for the underfloor heating that I would fit in the boiler cupboard and another wireless (thermostat / temp sensor) setup in the same room (in the app) but that would live in the kitchen. This system would match Rob's answer to this discussion:

Thank you!

Best Answer

  • GrilledCheese2

    If you want Tado to control both UFH and radiators, then you will need to remove both of the Honeywell BDR91s.

    The Tado wireless receiver replaces one of the BDR91s and the wired thermostat replaces the second BDR91. As you stated above, you need an additional wireless temperature sensor to group with the wired thermostat.

    Just purchase one starter kit, everything else should be sold as an add-on device.


  • Thank you @GrilledCheese2 that makes sense.

    So to recap I need:

    1x wireless receiver (to replace 1 Honeywell BDR91s)

    1x wired smart thermostat (to replace 1 Honeywell BDR91s)

    1x wireless temperature sensor (to go in the kitchen downstairs)

    4x TRV.

    Looks like it comes up a little bit cheaper to get the Wireless starter kit with an additional smart thermostat, rather than the wired starter kit with an additional wireless receiver :).

    Thanks again, it's good to know the wireless receiver and smart thermostat can be wired through the Honeywell control unit.

  • Yes, your list is correct. You don't have to install everything at the same time. If it makes it easier you can initially purchase the starter kit and replace the BDR91 for the radiators. Next upgrade the UFH. And finally add the TRVs.

  • Hello @GrilledCheese2 ,

    I'd really appreciate a bit more of your help 🙌.

    So I've replaced one of the BDR91 (connected to the radiator valve) with the wireless receiver, and installed the 4 TRVs and everything is working perfectly.

    Now I'm looking at replacing the other BDR91 (connected to the UFH) with the smart thermostat, however there is no instructions available because when I select BDR91 I get "You're trying to replace a wireless receiver..." message.

    I'm just wondering how should I wire the smart thermostat because there is a bridge inside the existing BDR91 (see photos). Any clues?

    Thank you!

  • My best guess so far is to do:

    SL -> NO

    L -> COM

    N -> P2

    But I'm probably wrong 😅

  • GrilledCheese2
    edited November 2022

    The bridge wire connected between L and A is not required.

    Connect L to CH COM.

    Connect B to CH NO.

    Connect N to P1. This is a neutral wire that is not used by Tado. The P1 terminal is just a slot to keep the wire safe.

    Because you've already replaced one BDR91, the app wizard may work better if you just tell it you're replacing a wired thermostat. If the app asks again what you're replacing try entering Honeywell DT90E, or a similar thermostat.

  • Just finished the installation and it works perfectly.

    Thanks again @GrilledCheese2 🙏