"Clonking " when boiler turns off

[franczola]

Hi,

A year ago, we had a whole new central heating system installed by a local well known heating company.

We have experienced problems from day one with leaks, failures etc.

We now have a problem with a loud "clonk" or "bang" that seems to come from the heating valve that supplys the radiators when the heating turns off. We hear the valve turn off, then a loud "clonk" that is loud enough to wake our 2 year old daughter.

It doesnt always happen, but enough to become annoying, and for a system that is less than a year old, isnt acceptable.
We have called the company out a number of times, but always seem to be fobbed off by excuses and remidial short term repairs that never solve the problem.

Can anyone please offer some impartial, honest thoughts on what may be causing this, so that we can get these people out to solve it once and for all.

Thanks,

 

[Boilerman2]

Have they fitted a ABV (Automatic By-pass Valve) it sounds like a high pressure differential accross the flow & Return causing the Mid Pos Valve to Bang shut when the pressure equalizes ...get em back!!

 

[electronicsuk]

More than likely caused by the motorised valve being fitted backwards. I also have the exact same problem, although I only have myself to blame in this case as it was me who fitted the valves. It doesn't bother me enough to make me want to fit them the correct way around - there are four of them in total!

I had already considered an ABV as suggested by Boilerman as a solution to the problem, although I'm doubtful if it would react quickly enough to be of any use. I'm also fairly sure that the boiler (Vitodens 100) has an internal bypass, which may also be the case for the OP.

 

[franczola]

Thanks for your help.

What does an ABV look like, and how do I know if the valve has been fitted the wrong way round?

 

[franczola]

Hi,

Just an update..

The company came back, and said that it may be due to a build up of scale? Which for a system that is less than a year old, i find hard to believe?

Anyway, they arranged a time to come and correct it, and bought the wrong part, so still couldnt fix it!!

They're coming (again) next week!

 

[kevplumb]

they are waffling you
simple as that

don't ask TELL them to get offa their asses and get it sorted

if it is scale there should have been some provision for preventing it stopping it at the outset

fwiw i don't think it is scale

i will go with the opinion on this one

methinks tha ball is loose in the valve

 

[boilerdoktor]

what boiler is it?? and is it a combi or system boiler??