Well. I have no links to share either but I’ve built a similar setup in my own house so I can share some experience.
A warning first. Make yourself aware it’s a complex topic. There’s many small variations in how existing systems work and no general solutions. That means there’s many potential pitfalls, so first and foremost don’t be naive and dig into materia deep first.
And yes, I’m sorry I need to tell you that your logic is flawed.
Some background first to avoid misunderstandings: According to common understanding, a thermostat is a thermometer plus a valve to open/shut water flow plus eventually one or more components as a “user interface” (mechanical handle, touchscreen, remote interface such as ZWave etc etc) PLUS a (usually simple) logic when to open/close.
In radiator heating setups, these are usually analog, mechanical and combined into one enclosure.
But in floor heating setups, thermometer, control logic and valve are separated from each other and located in different units and rooms. So your room thermostats aren’t really thermostats but rather thermometers with a UI and a output wire to send a signal when room temperature is below the target value, and your valves are just that, and inbetween there’s a control unit. Most of those simply forward the signal from the room thermostat to the valve to control water flow through that room.
There’s some control units to apply more complex logic and functions, though. Sometimes it also controls when to pump water through the circuits, and eventually it’s signalling the need to heat to the boiler or whatever ultimately is your water heating unit.
Once you start looking for that all I need is a good looking TRIAC based 3 wire thermostat which speaks Z-wave, you’ll notice you won’t find any. All of them are meant to operate radiators, they work based on the builtin thermometer and they don’t have any input port for a wire from the corresponding room thermostat.
Now even if you did find such a unit, there’s a major logic flaw:
If you replace the valves and start controlling water flow using direct zwave control, this will interfere with your central unit unless you completely remove that one from the control circuit.
Your central unit will still be operating the pump(s) or it’s talking to the boiler control unit to do so (in most houses, that boiler control unit will actually be controlling the pumps).
Key to a working system is to operate the pumps and to coordinate that with the valves. If you open valves but noone’s sending hot water, the system does not work efficiently or even not at all (you could set the pumps and “need to heat” contact to always-on but that’s pretty inefficient).
Now once you remove your control unit, you also have to re-implement all of its functions including the whole control logic (or at least some of it) in openHAB yourself.
Also note that the problem is not to replace the valve part (you can hook your valve actuator onto any openHAB-controlled on/off switch), but to replace your room thermostats. Today they just deliver a signal whenever temperature is below the locally-set threshold, but they don’t tell you the temperature. But that is what you need to know to do the control programming.
Effectively, you need to:
- dump your room thermostats and deploy an openHAB-attached thermometer into each room instead
- attach all of your valves to openHAB-controlled actuators
re-build (program) the whole heating logic including pump control (that’s key)
- build a new “UI”, that’s simple (it’s the openHAB UI).
Sorry for disillusioning you, but I believe that’s still better than to tell you to invest time & money and nonetheless get a nonsatisfying system.
And yes it can be done.
It’s a major effort, I did, my heating.rules is about 1k lines of code.
But once you made it, you can implement comfort features you cannot have in your exisiting system.
Here’s a thread to help you get going if you still want to.