4 Zone System Boiler & OpenTherm

Jason2024

Hi All,

Sorry for the long post...

I have been using Tado for a good few years in our previous house which had a Valiant Combo and then a Viessman 111W and Tado worked well, we added Tado TRV's later on and it was great to be able to turn off the heating in rooms we were not using for additional savings.

We have moved and our new house has an Ideal Logic + System s24 boiler. We have 3 heating zones all controlled with zone valves, these comprise of upstairs, downstairs and garage conversion. We currently have Honeywell T3R wireless thermostats upstairs and downstairs like these http://tinyurl.com/yeyvfn7z they are really not very good and every time you touch them it disturbs the battery and the screen goes blank grrr. In the garage conversion we have an ESI thermostat connected to a 3rd zone valve and a good old Drayton LP522 programmer for the hot water valve.

I have been doing som research and found this discussion https://community.tado.com/en-gb/discussion/comment/45099#Comment_45099?utm_source=community-search&utm_medium=organic-search&utm_term=thenicksenator

Interestingly our Ideal system boiler has Opentherm connections

We work away a few days a month and not being able to remotely turn on the heating is becoming a major pain.

I also have been looking at Ideal's Halo system which says it does Opentherm & can fully modulate 2 heating zones, however it lacks smart TRV's.

What I don't understand yet, is how the Ideal Halo heats the hot water and fully modulates the zones. My guess and I am waiting on Ideal to confirm is that when the Halo has a hot water time period set that it will then either closes the heating valves to heat the water at circa 70 degrees or it just says now I am heating water and tells the boiler to run at 70 degrees and thus during the hot water heating period the heating zones are then not modulated. As Ideal don't mention Priority DHW plumbing is required.

What I am trying to understand is.... can I get Tado to work in a similar fashion.

If I get a Tado Wired Smart thermostat and wire this to the Opentherm connections on the boiler, then if get a wireless starter kit with hot water control and connect this to the DHW valve and one heating zone then a further 2 x wired thermostats connect these to the 2 remaining zones as relay thermostats and then finally 2 wireless temp sensors for upstairs and downstairs.

Can I make this all work to gather and play nice. My thinking is that... if the wireless extension box is not connected to the boiler and is simply operating the zone valves and then the wired thermostat connected to the boiler via opentherm for the modulation.

I really like the Tado app and functionality and the investment I made in the valves I don't want to loose.

Later on I may swap the Ideal Boiler for a Viessman 100W which has a separate Cylinder flow and heating flow and return. Don't think a combi will be a good fit as the area has particularly hard water and is a larger property so having a unvented tank is great so as not to loose pressure when running 2 showers. We have very good water pressure as the pumping station is very close by.

Any thoughts or ideas would be appreciated.

policywonk

May I ask why the zone valves are in place? If the rads have their thermostats, what additional role are you expecting from motorised zone valves?
In my experience tado rad stats will open or shut a rad according to the set temp, allowing one to moderate temps by time of day on each rad. When a smart rad stat closes its valve, it effectively drops that rad out of the pumped loop that the motorised zone valve is feeding. If one follows the logic, when all rads in that loop shut off, they effectively turned off the loop whether or not the motorised zone valve is open.
Now as long as your boiler or pump can throttle back, or up, as needed, you may not need multiple zone valves for CH if you are going to apply smart rad stat heads from tado. Hope this makes sense.