Wavin ufh manifold problem

[steve1]

We've just had, ( 2months or so ), wavin ufh installed, everything ok until a few days ago when the whole manifold started to vibrate really badly, narrowed it down to the thermostatic actuator bouncing, ( for want of a better word ), tried adj it to stop it, ok for a few seconds and then starts bouncing/vibrating again.
i might add, this is the valve that looks like a trv and is situated on the left hand side by the pump.
After a few calls, the plumber who installed called round and has decided that the valve inside the body is faulty and is ordering a new part.
I'm not convinced about this, but will let him replace it and see. Meanwhile, I was looking around the various forums and come across another similar thread from a few years ago which concluded in a by pass valve being fitted to the manifold due to the water pressure being too high, unfortunately the person who started the thread never stated if this was successful or not.
Has anyone come across this problem before, and found out the problem, I'm not saying the valve isn't the issue, and all will be resolved when it is repaired, but at this time of year I really don't want to be without the ufh for too long.

 

[diamondgas]

Hi steve1 ... Not familiar with the particular manifold you talk about .. picture may help? However if it shuts off the flow to the UFH and there's no other place for the supply to flow through then you may well get 'chattering' occurring. An automatic bypass on the heating system should resolve the problem as it will open as the UFH shuts down maintaining correct flow through the system

 

[steve1]

I'll try and get a picture up, if I can work out how.
The valve doesn't chatter when shutting off, it chatters under normal running conditions, it's basically a mixing valve that looks like a trv.
I've since tried slowing the main boiler pump down and lowered the system pressure slightly to see if that stops the noise, but alas it didn't.
looks like I've managed to get a picture loaded, the valve in question is the bottom left, with the blue top to it.

 

[diamondgas]

May be a silly question but are the pipes the correct way around .... the one below the 'red' should be hotter than the one below the 'black' valve

An auto bypass either between the two supply (red & black) or main primary Flow and Return pipes, set up correctly, should reduce the flow through the valve and the potential for 'chattering'! IMHO ...

 

[Chalked]

I'm with above. Flow and return crossed.

 

[steve1]

The ufh has been running fine for about 2 months, then it just started happening, so the basic layout must be ok.
The only thing that I did was to put some inhibitor in the system, but that was done via one of the rads. and then filled back up and bled.

 

[Jimbob]

Not necessarily. Definitely worth a check. By pass valves is a must also else I have found the mixers to be noisy if none is provided.

As the manifold heats it shuts the flow, so any system pump pushing can cause the noise.

 

[kimbo]

Why dont you ring wavin they will tell you. I think you neef to contact thermoboard they supply their system and the tecnical dept is very good. I have used them several times.
The auto by pass may already be installed at the boiler end already

 

[steve1]

Why dont you ring wavin they will tell you. I think you neef to contact thermoboard they supply their system and the tecnical dept is very good. I have used them several times.
The auto by pass may already be installed at the boiler end already

i have tried to ring wavin a couple of times and they have never returned my calls, I will try them one more time though.
I did mention that there is a by pass already installed by the motorised valves.

 

[Ermintrude]

Your system should have a biocide not just inhibitor af10 or similar. That won't be the cause of problems but it's a good prevention of others.

Have you been modifying other parts of system? Does sound like over pressure on trv head ( much like when you have a combi with no bypass and all trvs)

 

[steve1]

I really should have updated this before now, problem was the actual valve itself, they had had quite a few complaints, I think they just made the internal spring a bit stronger.
Anyway, seems to have cured the problem.
But I could do with some advice on another problem i have, but I'll start a seperate thread titled pressure vessel.