Thud noise when water is turned off - why?

[Flossie]

We had our house modernised a few years ago and all went well. We had a new extension with utility room and cloakroom; new kitchen and new bathroom.
After about a year we began noticing a loud thud when the sink taps were turned off after use. We still get this noise, which also happens when the toilet flush has refilled.
We cannot think why it is happening - we both are not in the plumbing trade! Mr Flossie has tried the usual things to check the system. He thinks we will just have to put up with it! Men, eh!!??
I am still wanting to solve it though, and so I would appreciate your advice please.
Flo

 

[WHPES]

See this link

http://www.ukplumbersforums.co.uk/p...mmer-after-new-toilet-fill-vale-instaled.html

exactly the same problem.

 

[Flossie]

Hi, I already searched this site for similar things and found that one. We did not fit a torbec valve, my other half says, so I discarded that as a reason for our thuds! It was interesting to learn about that one though.
Would there be any other reason for the thuds? Maybe we will have to put up with it after all then (?)

 

[WHPES]

Doesn't matter what type of tap / valve it is, the action and the symptoms are the same - sudden shock of shut off of water causing the pipes to bang. The situation is known as "water hammer" Are all pipes clipped to the wall properly? Otherwise consider installing a PRV or water hammer arrestor as stated in the other thread.

 

[Cds]

The thud is caused by “Water Hammer”. What happens is that the valve or tap shuts suddenly resulting in a pressure wave travelling at the speed of sound back along the pipe until it hits an obstacle such as a bend or change in pipe direction.

At this point the wave can either dissipate or it can be reflected, if it is reflected the noise can be akin to a machine gun as the wave bounces up and down the pipe. If the pipe is not securely fasten it can be ripped off its fixings.

There are two approaches to resolve water hammer:

1) Water hammer is related to the velocity of the water and slowing down the water flow can cure it. Try restricting the flow to the offending appliances or even closing the incoming stop tap a little.

2) If this does not cure the problem have a water hammer or shock arrestor fitted. This absorbs the energy of the wave so that it is no longer a problem. Plumb Center Online

 

[Flossie]

Thanks for that info and the link to Plumb Center Online, which I have just seen. They have three choices! I'll wait till Mr Flossie gets home now, for his input on this one, as I've done all the asking and have had your help.
I thought the problem was caused by the Torbec valve on that other thread, so sorry about my not realising that it would be caused by any type of valve or tap.
Our pipes were definitely well secured to the walls or beams as my other half asked them specifically to ensure that they did that because we'd had noisy pipes before the modernisations, so we made sure they were well clamped. I realise, now, that they could still come loose, with vibration I suppose. Looks like a no-win situation - until we get that arrestor fitted, that is. We will ask at the shop which one to get.
So then, that is our problem answered, and it's up to us to get it solved. Cheers, and thanks for your advice,
Regards,
Flo

 

[WHPES]

see

[DLMURL="http://www.masefield-epson.co.uk/plumbing-products/20/21.html"]Masefield-Epson | Dealing with Water hammer Problems[/DLMURL]

 

[Smcart5]

Is it just just the one tap or both?, my tap needs a new cartridge as it can't open/close properly and it slams shut when turned off causing a loud thud.

 

[Flossie]

Hi Smcart5, sorry to hear of your problem with your tap, in your case just the one.
In our case it is the whole lot in our house: the hot and cold taps everywhere. The toilet too, after the cistern fills. Even the washing machine makes a noise when the water stops. I have seen that website from the link in WHPES's message (thanks for that one) and I see that Water Hammer can do damage if not fixed.