Replacing Nest with Tado


Hey folks!

We have a pair of Nest Thermostats with a single combi boiler (Valliant ecotec 832).

This boiler runs two heating zones, hydronic UFH downstairs, and rads upstairs. There is Nest Heatlink wired into the wiring center next to the boiler. There is a second Heatlink wired into a wiring center next to the UFH manifold. The boiler and the manifold are physically around 10ft apart. (Interim question here: is this standard?)

One of the Nests has died, and I’ve disliked the Nest Ecosystem since Google acquired them, so I’m thinking of changing to Tado, to gain access to TRVs, among other things.

Is it just a case of buying 2 Wireless Stat kits, swapping out the heat links and the stats, and basking in the glory of a job well done?

Or, is it much more complicated than that? A few folks have said that I only need one wireless receiver, but how do I wire that into the UFH manifold?

I’m happy working with 240v if it’s a simple job (I.e. a straight swap), but does it sound like I should call a heating engineer to unpick the current system?

Thanks folks!

Best Answer

  • policywonk
    policywonk ✭✭
    Answer ✓

    Am not an installer, but have had to install, myself, a similar set up at my home, with one manifold running the UFH downstairs, and upstairs the rads being controlled by TRVs. The wiring centre thats linked to the UFH manifold will have the following components:

    1. Specific valves are assigned at the wiring centre controlling each individual UFH heating loop. These valves can be wired in such a way that they can have either individual thermostats driving each valve, or maybe one thermostat driving many valves, or a combination (hope that makes sense). Usually - and it is best - the relationship between the thermostat and the wiring centre is a wired one- because when there is a problem in the system it is easier to debug than when wireless thermostats control those valves. If you have only ONE heatlink controlling the entire manifold, I presume that there is ONE wireless receiver to link into the wiring centre.
    2. When one or more of the valves are opened because one or more thermostats call for heat, the wiring centre driving the manifold will also trigger (i) the UFH pump, (ii) a two way valve to provide heat into the manifold and (iii) call for heat from the boiler for the entire system. There will be a trigger wire from the wiring centre to switched live for the boiler and the two way valve.

    Thus guide : - should help you identify how the boiler and wiring centre are wired in together and understand how the boiler is triggered.

    Replacing the Nest heatlink for the UFH isnt a big deal, will probably take you about 2 hours in total once you've figured out the wiring. For that it helps to download manuals for the wiring centre and study how the wiring centre was in fact set up - it enables you to see how it all fits together.

    Then it is a simple matter of replacing the Nest receiver with the wiring to the Tado Controller. Before you take another step please pause and consider whether you need to install more thermostats on that UFH system - as this will be crucial in reducing your operating costs.

    Once you have the Tado controller talking to the wiring centre, with one more more wired thermostats the basics have been achieved.

    The Tado app will guide you through this and Tado do have decent support when you hit a glitch. Come here if stuck.

    When this basic component of the setup is completed, you can consider replacing all the radiator valves with dedicated Tado TRVs - there is a benefit because they have the capacity individually to call for heat when they need it.

    This leads to a need for a further check to be made. Please check your plumbing and confirm whether there is a second zone valve determining whether heat goes upstairs, which also drives a second pump dedicated to the upstairs heating loop. This picture should help.

    The important thing is to ensure that your wiring centre is able to control the zone valve for upstairs as though it is yet another heating loop. The Tado controller will then handle the rest.

    Hope this is clear.


  • therealsn

    Hey @policywonk!

    Thanks so much for your extensive response! For now, we're going to stick with Nest as I was able to get a replacement back for our existing stat. But, I'd like to move over to Tado eventually, mainly for the TRVs (our daughter likes her room a lot warmer than ours!), and your instructions are perfect!

    Thanks again!