Loud knocking on pipes

[harbour]

Hi, If anyone can help me with this problem it would be most appreciated. There seems to be something happening to our plumbing system. When you turn a tap off (either hot or cold), there is a loud knock throughout the pipes. This also happens when the shower is turned off and when the washing machine is working i.e. filling up. I don't know whether or not this is related but the toilet is also making a constant flowing noise when it has been flushed, sometimes though if you flush it using economy flush it doesn't happen. I don't know if I have provided enough information, we also have a combi-boiler and central heating with no water storage in the house. Hope this makes sense and I look forward to hearing any suggestions as to why this happens. Kindest regards

 

[Alanka]

Hmmm.... Sounds like water hammer, that is a shock wave caused by abrupt shut-off of water flow in a high pressure system (?) Does it happen if you shut off the taps slowly? (Washing machines and dishwashers usually shut off very abruptly.) It shouldn't happen if the cause is indeed water hammer.

You could try partially closing the mains water cock to reduce flow to see if this helps. If not, then a pressure reducer for the whole house might be called for if your mains pressure is very high (get it measured).

The constant filling noise from your wc may not be connected, but it could well be a failing sealing washer in the flush mechanism, that lets water flow into the pan. Or the float valve may be not shutting off properly which would cause overflow into the pan. Look in the cistern to see if it is overflowing when this noise is happening. If so, get the faulty unit serviced or replaced.

Hope this helps.

 

[REDSAW]

follow all your plumbing around the house and look for a pipe that has slipped of its clip.
it is due to this the pipes are whip=lashing against a floor board or kitchen cabinet etc.
start around the combi, get someone to hold the pipe and one to open tap.

 

[harbour]

Thank you so much for your replies, it really is appreciated. The pipes do not make the noise if they are switched off very slowly so I suspect this bears some significance to the diaqgnosis. Can anyone tell me what to do about this hammer thing (sorry to be so stupid) but plumbing is a mystery to me. Meanwhile, I'll check for loose clips as suggested. Look forward to hearing from you. Kindest regards.