Multizone UFH plus rads plus HW

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Upstairs I currently have an old wired thermostat with a Honeywell controller for HW and heating. I will replace this with a wireless starter kit and Tado smart radiator thermostats.

Downstairs I have multi zone (5) UFH with old wired thermostats which link to a wiring system with manifold, pump, valves, actuators etc.

If I replace the old wired thermostats for the UFH downstairs with Tado wired thermostats, I expect the wiring centre will still be doing the communication to the boiler / pump etc for controlling the UFH.

But with both upstairs rads stats and downstairs wired stats both using the Tado app and the 2 channel (HW and Heating) Tado controller, will the tado system also ask for heat when the downstairs stats ask the wiring centre for heat. i.e. will I end up asking the boiler for heat twice, i.e. will the central heating come on upstairs (on rads without tado) whenever UFH is on or will the Tado system ignore the wired thermostats downstairs - i.e. it only controls their settings and does nothing when they ask the wiring centre for heat.

Also, and not wanting to complicate the question, but upstairs I currently have the old wired stat, so it's easy to simply replace this in place with a wired Tado stat rather than the wireless one that comes with the kit. But will the Tado system know that if this asks for heat, the central heating needs to come on unlike with the wired stats to the wiring centre downstairs. Just comparing to my old controller/stat, if that was heating ON, then it's down to the thermostat setting. So I imagine the Tado wireless receiver is effectively always sending the equivalent of ON to the boiler, thus letting the upstairs wired thermostat control or the tado rad stats control the central heating request?

I guess the root of the questions could be whether the wireless receiver communicates at all with wired thermostats or does the app and internet bridge only communicate with those.

I hope my questions are clear, sorry for rambling. To summarise this is what I want to know works:

Downstairs UFH plus 5 wired stats connected to pump/manifold etc.

Upstairs : A few tado radiator stats plus existing wired stat for all radiators that I might not have added a Tado stat too which would be effectively an extra zone.

I want HW to work, and all the zones to work individual zones to work independently.

Best Answer

  • GrilledCheese2
    GrilledCheese2 ✭✭✭
    edited October 2022 Answer ✓
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    You should be able to use Tado thermostats by using terminals 1 & 2 in the wiring centre for switching each zone. In the documentation there are options for an external floor sensor and a time clock module, you wouldn't be able to make use of these if fitted to your system. Tado thermostats don't use a Neutral wire, so you would need to isolate this wire in one of the parking terminals.

Answers

  • GrilledCheese2
    GrilledCheese2 ✭✭✭
    edited October 2022
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    First thing is to check the type of wired thermostat currently used by the UFH wiring centre. The most common type of thermostat is just a switch; the circuit between two wires is opened and closed based on the demand for heat. If the UFH is using this type of thermostat then you simply replace them with Tado wired thermostats. Some UFH wiring centres use proprietary controls where you have to use the manufacturer's thermostats. This type of system will not be compatible with Tado or any other smart thermostat.

    Upstairs you will need to use a wireless thermostat if you want to use the Hot Water Wireless Receiver device. It's easy to setup.

    The existing thermostats will not interface directly with the boiler. Your UFH wiring centre may be the only device that communicates to the boiler for the whole home. Or, it might handle only the downstairs and the motorised zone valves for the upstairs have their own connection to the boiler. Replacing wired thermostats should not affect how the different hydronic zones are activated.

    If you install smart TRVs upstairs then you link them to the wireless receiver in the App. The wireless receiver will be the Zone Controller for upstairs and ensure the upstairs and UFH can operate independently.

    If you are going to DIY install the system I'd suggest you install the wireless receiver and wired thermostats first. Check the heating system is functioning correctly and then add the TRVs at a later date to get finer control of the upstairs rooms.

  • rado_tado
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    Thanks for the advice. I will check the wired thermostats, I think they are just standard but will try to research if they are normal ones.

    Upstairs has its own motorised valves and connection to the boiler. The downstairs UFH is completely separate.

    I think the key point you have made for me is that I need to use the wireless thermostat upstairs and that the UFH will remain separate with the wired thermostats. And to do the TRV on the radiators last rather than a big bang approach..thanks!
  • rado_tado
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    Great, thanks for taking the time to look at this for me. Much appreciated.