BMS is clearly commercial, although there are some domestic home automation products that will monitor and switch on CH, not do the controls.
They are unsuitable for this application as better and cheaper solutions are around.
Landis & Staefa do v good one, I have an old one still in its box in the garage. Forget the model number. All the large controls people will do one.
I am.
Simulated proportional feedback controls are "excellent" and do a wonderful job. BMS system have come a lot way and that they now can control, whereas the originals were monitoring and simple digital (on-off in BMS terminology) switching systems. I have experience with Landis & Gyr Visonic and Honeywell Delta systems. There is no reason why domestic BMS system cannot be cheaply available. All is needed is an I/O module where the valves, sensors, relays, etc are connected, and the module to a P/C and the appropriate software. Simple and easy. Not rocket science. The skill is setting it up, which the avearge DIYer will have a hard time doing. Getting a plumber to set one up will be near impossible.
The UFH valve will open full allowing full heat to the UFH. It will probably not be enough. If so then the rads come in to boost. When set point is near it starts to back off and the rads immediately are modulated down and then to off, with the UFH still full on.
The UFH is will be undersized, that is the point. On mild days only UFH will be required.
That is UFH for you, but this will be an undersized UFH system. The instances when the rads come in, the UFH will not be coping.
I'm not sure he has. He needs to see if a UFH system will cope first. If not abandon the UFH and stick to rads modulated by a good load compensated condensing boiler.
Compensation is feed forward control, it reduces the cold and hot spots and prevents temp under and overshoot.
That is why weather compensation is "vital" with UFH.
You can have room, wind and solar influence with a compensator. Extra modules and sensors.
That is using a two stage controller.
Two different solutions. The two stage controller will be expensive as it is commercial. Cheaper domestic compensators are available.
All clear now?