Knocking Pipes

[TT88]

Hi All,

A few years ago, we extended our property and installed underfloor heating (wet system). Our plumber T’d off existing pipe for central heating rads and installed two motorised valves. Since changes have been made, we hear a knocking in our pipes when we flush toilet, use taps / bath / shower and machine. This doesn’t happen when central heating is running throughout winter. Going into summer we have turned central heating off and the knocking has returned! Any ideas?
A photo attached showing two motorised valves in stitu.
Thanks for reading
Tim

 

[Wayners]

Look at water hammer arrestor

 

[TT88]

Thanks Wagners. Our plumber fitted them but still get the knocking

 

[fillyboy]

Look at water hammer arrestor

Thanks Wagners. Our plumber fitted them but still get the knocking

Not a plumber but I gather the location of the arrestor is critical.

 

[Deleted member 294929]

If it's water hammer then is a process of elimination.

●Is the main isolation a stop cock or have you got stop cocks inline?
●Have you got Pt 1 or Pt 2 bullvalves on tanks in loft
●Are the ball valves in your toilets of an older design?

●Next time the banging happens open and close taps.