Hammering pipes

[RayPooley]

Hello all

This is a new installation a friend of mine has just had completed in her cafe.

She can't contact the plumber who did the job for some reason. Not picking up.

It's only a week old.

He has just fitted a sink in a part of the cafe and the pipes are hammering like hell
when you turn off the taps so much so that they are jumping out of the clips and
you know how tight those things are. They won't even reach the clips in some places.
It's as though he has cut them too short.

The joints are all compression and there are 10 x 90 degree elbows in each of hot and cold
water supply that I can see and maybe a few more that I can't see.

For now I have turned down the mains pressure as much as I can and it has gotten rid of the
hammering on the cold supply but the hot still has a ping. That's because the only
means I have of reducing the pressure on the hot supply is an iso.

The problem with this is that there are dishwashers and central heating needs
to consider so I would rather have full mains pressure and to that end I consider this
a temporary solution at least for a couple of days.

I attach a picture of what's going on under the sink. If this guy doesn't turn
up in the next few days I am thinking of removing everything under the sink between
the isos and the taps and replace it with flexi hoses.

Will that help dissipate any of the energy in the pipes? I mean through movement
off the flexi hoses?

Take a look at these pics. Is there any kind of small expansion vessel available that
might be suitable for this? To buffer the shock?

The wastepipe is leaking too, which is easy I know, but I am reluctant to get involved
given this is only a week old and I don't want to give this guy an excuse to wash
his hands of it by touching it.

Any advise appreciated.

Cheers

 

[ShaunCorbs]

Sorry to say that’s no plumber more like a handy man try replacing the tails for flexis

 

[RayPooley]

Sorry to say that’s no plumber more like a handy man try replacing the tails for flexis

I didn't like to say but I agree.

got him out of the local classified ads.

He hit her up for £400.00.

Thanks for the sanction.

 

[michcosg]

The pipework looks all OK to me. Personally I am ok with using compression joints in above ground and reasonably visual accessible situations so long as well clipped as they are in this case. Flexi's have the under appreciated issue of easily corroding if water leaks from above on or where there is condensation due to poor ventilation or a poorly specified or located fan.

As regards the water hammer issue, this might be the sinks new taps. Are they quarter turn (ie ceramic disk)? These more modern and I accept convenient tap type have the consequence of more severely shutting off the water supply thus sending shock waves back through the pipework and causing water hammer.

Still most pipework can handle this but occassionally I have encountered a usually old quarter taps that doesn't quite shut off and have gotten this problem. The already alluded to solution of changing the taps tails to flexis might sort it. As might turning down the water coming into the property at the mains stopcock* I have also changed a properties main stopcock and think this may have done it.

* Note turning down the mains should also equally affect the hot waters pressure as its the same line going to your combi, unvented cylinder or thermal store. It might need more tweeking however at an ISV on account of it being heated and thus increasing its pressure.

Note generally however this is more likely also to be a problem with sites having a water meter (ie most likely the case with a cafe) which I think also incorporate a double check valve ....which will stop water expanding back into the main and thus more likely to cause water hammer!

I am assuming the cafe has a water meter with a double check valve. Are there any other quarter turn taps in the cafe that are not exhibiting this problem? Does the problem occur when you run the sinks taps and slowly turn off at an isolation valve (isv) under the sink? Do you know what the water pressure is into the property? Has the properties internal stopcock being renewed?

Possible solutions include:

1 Turn down the the flow of water into the property at the stopcock and to the sink at the ISVs
2 Change the taps tails to flexis
3 Fit a new internal stopcock
4 Fit new better quality 1/4 turn taps
5 Fit water hammer arrestors on pipework just down from the taps and before the ISVs
See link Sioux Chief DW660-2J Water Hammer Arrestor ½ - https://www.NoLinkingToThis/p/sioux-chief-dw660-2j-water-hammer-arrestor-bsp/1492r 2 x £21!
6 Change the taps to full turn taps (washered)
7 Install a pressure reducing valve - requires yearly maintenance!

Note however having shut your water off and for example changed the stopcock, the problem may appear to be fixed only for it to return! This I think is because having drained down you have effectively introduced some air into the pipework which will act as a buffer or water hammer arrestor until I presume the lines have been purged of air by people using the taps.

Queries or thoughts welcome.

 

[RayPooley]

The pipework looks all OK to me. Personally I am ok with using compression joints in above ground and reasonably visual accessible situations so long as well clipped as they are in this case. Flexi's have the under appreciated issue of easily corroding if water leaks from above on or where there is condensation due to poor ventilation or a poorly specified or located fan.

As regards the water hammer issue, this might be the sinks new taps. Are they quarter turn (ie ceramic disk)? These more modern and I accept convenient tap type have the consequence of more severely shutting off the water supply thus sending shock waves back through the pipework and causing water hammer.

Still most pipework can handle this but occassionally I have encountered a usually old quarter taps that doesn't quite shut off and have gotten this problem. I have also changed a properties main stopcock and think this may have done it.

Note however this is more likely also to be a problem with sites having a water meter (ie most likely the case with a cafe) which I think also incorporate a double check valve ***.which will stop water expanding back into the main and thus more likely to cause water hammer!

I am assuming the cafe has a water meter with a double check valve. Are there any other quarter turn taps in the cafe that are not exhibiting this problem? Does the problem occur when you run the sinks taps and slowly turn off at an isolation valve (isv) under the sink? Do you know what the water pressure is into the property? Has the properties internal stopcock being renewed?

Possible solutions include:

1 Fit a new internal stopcock
2 Fit new better quality 1/4 turn taps
3 Fit water hammer arrestors on pipework just down from the taps and before the ISVs
See link Sioux Chief DW660-2J Water Hammer Arrestor ½ - https://www.NoLinkingToThis/p/sioux-chief-dw660-2j-water-hammer-arrestor-bsp/1492r
4 Change the taps to full turn taps (washered)
5 Install a pressure reducing valve - requires yearly maintenance!

Queries or thoughts welcome.

All reasonable suggestions which, collectively, amounts to redoing the job.

I'm favouring flexi pipes followed by the anti-hammer valves if that doesn't cure the probem..

He has fitted stopcocks for taps requiring at least 3 full turns before water emerges.

Pipe work leaves a lot to be desired. Fitting clips to walls and expensive parquet floor????
Landlords not going to be at all happy with that. She doesn't know yet.

Pipes too close together and don't fit into clips. The ones that do pop out when the hammering starts.

I think Shaun's assessment is most likely the case.

Bit of a dog's dinner.

Cheers