Choice of smarthome system for Thermona THERM 28 KDC oven with opentherm

I would like to build a smart-home system at my home, starting with a heating upgrade, and I'm in a conundrum as to which system to go for. For a start, I'm keen to control the temperature of individual rooms (including hourly schedules) from my phone via the internet, switching on the water heating on assumptions: I have a Thermona THERM 28 KDC combination furnace, which currently works with a Honeywell CR 04 controller (with outdoor temperature sensor, opentherm communication). The house uses underfloor water heating (4 loops for 3 rooms) and radiator heating -> I need 16 heads.

I'm confused, I wanted to go for the widely available zigbee/tuya solutions, but I don't see controllers that communicate in the opentherm standard. From the market solutions I see that Tech/sinum controllers have this solution, e.g. Opentherm St-2801 (the rest of the kit components quite expensive) -> is it worth spending that much on this system? And a cheaper system from provisolar (PH-PK25-p225), but the units themselves already look old. Please help me in choosing a system, assuming the controls will be in the same ecosystem (if this is a correct assumption .

Honeywell Evohome

If you have underfloor heating and radiators, it is worth considering a hydraulic coupling, a mixer with actuator for the underfloor heating and a separate pump for the radiators. All this and the boiler can be controlled by Tech i2 via OpenTherm.

Plumpi wrote:

Honeywell Evohome

Since you have underfloors and radiators, it's worth thinking about a hydronic coupling, a mixer with actuator for the underfloor and a separate pump for the radiators. All this and the boiler via OpenTherm can be controlled by Tech i2

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I hadn't heard of the Honeywell Evohome - thanks, I'll have a read. I'm getting closer to building a system on HA though, I see some solutions are available on opentherm.

The items you mentioned - clutch, mixer and separate pump are necessary if the controls are changed? The cooker is about 17 years old and probably won't live long - when replacing the cooker I'd like to retrofit the system with the items you've listed - is this a good idea (the most urgent is currently changing the controls to remote)?

Pete12 wrote:

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The items you mentioned - the clutch, mixer and separate pump are necessary if you change controllers?

No. They are needed to make everything work well when there is a mixed installation i.e. there are underfloors and radiators.