Viessmann boiler, weather comp and UFH urgent advice

[puc]

Ok here’s the situation, I am a home owner (not an installer) and I am looking for some clear advice for a heating system I'm looking to have put in over the next 2 weeks.

The house is a semi with 4 bed 1 bath, and 2 en-suites. We are considering a Viessmann 222-F WTC, and I have spoken with Viessmann technical and the Viessmann installer but all have suggested different installations with different pros/cons.

We are looking to have radiators throughout the house, and then UFH in the kitchen, and the 3 bathrooms.

I understand that the UFH circuit needs a lower temp circuit and this could be done in one of two ways, both of which result in a lower temp, boiler controllable circuit for UFH
Solution A] Sub-mounted mixer assembly or
Solution B] 3-Way valve, extension kit (with integral actuator and temp sensor) and pump

However, I have 3 rooms which need UFH, and the boiler can apparently control 1 direct circuit, and up to two mixed.

One tech guy suggested using low loss header and normal zone valve/pump type system for UFH rooms and room stats, really!?

Question
How can I have control over the 3 UFH rooms as they all would share one heating curve? Can I just use Solution B (my preferred) and then zone the mixed, lower temp UFH feed somehow?

Is there any better ways to do this?

Thanks in advance.

 

[Agile]

What you are asking about is something of a nightmare!

If you paralleled all the UFH heating rooms then it would be possible to get reasonable operation and you could have manifold valves on each to have individual control.

But the cost of doing what you want PROPERLY is very high indeed, perhaps £2000 !

My view is that it will not be worth it.

I know that a nice UFH system with no visual and physical heating emitters on view is attractive to all home owners. But achieving the same level of comfort and control as radiators is very expensive indeed. There will also be many installers who dont really understand whats required either.

So how will the temperature of the UFH circulation be controlled by your "B" scheme?

Tony

 

[puc]

Hi Tony,

Thanks for your feedback. The Viessmann tech told me that the B circuit has its own heating curve ont he boiler so can be set to the desired temp of say 40 degrees. A sensor on the mixer valve reports this back to the boiler and then the boiler adjusts the water temp accordingly.

Without a room stat based (normal) system though, I'm not sure how weather comp actually works in terms of air temp in reality.