How do I cure knocking cold water pipes ?

[Aquaheat]

are you a plumber, I know what he posted and I know what im on about do you

Plumber and heating engineer for about 10 years now. Thanks for asking. Not on this site to start grievances. If you read the post the OP has no problem with the heating system and only a fault when the toilet is flushed. The two systems are completely separate.

would you change the oil if you had trouble changing gears?

it has nothing to do with your heating.

Thank you bengasman

To the OP,

It sounds like you have a torbeck valve fitted and if the stop tap wasn't fully open in the first instance you may have been lucky and it has reduced the pressure enough to allow the valve to operate properly albeit with a slight banging to start with. These valves have a pressure reducing kit supplied with them that should be fitted to systems that operate on a higher pressure. if the stop tap is now fully open and the pressures have changed this may be a cause for the noises that you are experiencing.

 

[JBrennand]

you do not get air trapped in mains water, too much pressure and/or loose pipework is causing the problem, and as it is a plumbing prob dont expect to get it fixed by BG

Cheers for that.

I have the plumbing cover via BG contract - they outsource the work to Dynorod plumbers.

Cheers

 

[JBrennand]

Sounds like you have torbeck valves. These always shut off with a clunk. Thats because they use mains pressure to close themselves off. When you buy them they have plastic spirals that look like Fusilli The finer of the spirals provided reduces the pressure and hence quietens the valve shutting noise. Clipping loose pipes and thermal insulation if appropriate will help dampen the noise.
.

Thanks for that. A mate has suggested swapping to a "Fluidmaster" valve (see link) as they work better than Torbeck's in systems with a higher pressure. This may be the easiest solution!

John

http://tinyurl.com/7jehvx

 

[Elboy]

This problem has been bugging me for ages too. Every time i turned on the cold water tap full and off quickly i heard the knocking sound. Turn it off slowly and no sound. To make matters worse it seemed to happen every time next door used their taps too. God knows why.

Thanks to jonjb i have finally fixed it. It was indeed that the cold water pressure was too high. I did exactly what he said and turned the cold tap on and slowly closed the internal stop tap to reduce the pressure and hey presto NO MORE BL**DY KNOCKING NOISE!!. Thanks jonjb.