Tado v3 opentherm connecting to Logic System Max boiler

rlaw86

Hi, I currently am having central heating system and boiler installed, no existing CH so everything is being plumbed in new.

I've been speaking to the heating engineer and they are struggling to figure out how best to install to allow me to use Tado with opentherm support.

From the reading I have done I would need a X-Plan (PDHW) which will allow me to connect the Tado in such a way that will allow Opentherm support.

The boiler is Logic System Max S22 with an unvented cylinder. I purchased a Tado v3 starter kit EU version and TRVs for the majority of the radiators so don't think I require different zones for the CH.

Can anyone advise if what I am trying to achieve is possible and how it should be wired/plumbed?

I've found the following wiring diagram which uses a Nest and the heating engineer for now is following this and if we get to the point where we can't get Opentherm working then will fallback to just connecting the Tado for the relay.

policywonk

It is possible, if your heating engineer can replace the on-off dry thermostat with one that will engage opentherm, then the rest is easy to handle. Suggest you contact Ideal and ask them if they can recommend an Opentherm cylinder temperature sensor to replace the original thermostat. If they can recommend one, then contact Tado support:

1. Identify the boiler model.
2. Identify the tado bits you have.
3. Explain you are willing to have your zone valve removed. If you prefer you can add an automatic bypass valve to help the boiler shut down more quickly when all the radiators are shut.
4. Identify the cylinder temperature sensor recommended.
5. Ask them to give you a confirmation whether it can work in Opentherm and provide you instructions on how to complete the change.

Come back and let us know how this proceeds. A lot of people hit this hurdle but it has been crossed.