Viessmann 222F with Weather compensator & UFH

[stewy66]

Hi,

Just had this boiler installed and need to fit UFH, I have got the following Viessmann parts:-

valve 7338214
22mm conns 7207285
Actuator 7441998

But we are not sure how this works with the boiler as there are no installation instructions?

1. How does the three way brass valve link into the heating circuit, does the return from the UFH return to both to the valve and the boiler via a T joint?
2. Do we need a pump on the UFH circuit and if so where do we connect this to the boiler?
3. Where does the flow temp sensor seat, on the outward flow or return pipe?
4. Does the room where the UFH circuit is installed need a room stat and does this need to communicate with the boiler?

Any help greatly appreciated.

Stuart

 

[Agile]

Is the boiler installer not trained and an accredited Viessmann engineer?

 

[stewy66]

No the plumber I am using is a friend of mine, he is gas safe with many years experience with installing boilers.

But unfortunately, this is the first Viessmann boiler he has installed.

Viessmann Technical support have now kindly answered my questions so far, so we will see how we get on from here, answers below.

1. How does the three way brass valve link into the heating circuit, does the return from the UFH return to both to the valve and the boiler via a T joint? Yes, to the side branch and the boiler return.
2. Do we need a pump on the UFH circuit and if so where do we connect this to the boiler? Yes, plug 20 on the actuator.
3. Where does the flow temp sensor seat, on the outward flow or return pipe? Flow.
4. Does the room where the UFH circuit is installed need a room stat and does this need to communicate with the boiler? No.

 

[Agile]

You may not get the longest warranty if the boiler is not commissioned by an accredited installer!

That might only cost about £84.

UFH is another black art and if not designed correctly may not function very well.

The worst problem people have is designing and setting up the controls and particular the timing.

I am helping someone whose nupty installer fitted the cylinder sensor not to the cylinder but to the heating coil pipe 2m away from the cylinder. Not surprisingly the cylinder was not getting heated properly!

Tony