Could I have caused this water hammer?

[WaterTight]

Hi,
I removed and replaced a small section of copper pipe with a new section as it had a leaking soldered joint.

It was under the kitchen sink, about 300mm max, with a few tee's on it that were splitting off to feed washing machine, kitchen mixer, and off to supply other parts of house. The section was immediately after the main shut off valve, which is a lever type not a traditional stopcock. I re-used all the original valves and just re-did the soldered pipe. All valves are lever type and all were fully on both before and after the repair.

Since then the customer has found any use of any outlet on cold mains creates a small thud sound. I've returned and confirmed this.

Since no valve/tap has been replaced or worked on I've no idea which one might be causing this sudden appearance of water hammer. He says he hasn't noticed any increase in pressure and spotted no work being done on the mains outside.

How do you diagnose what is causing this? Or would you just try and fit a shock arrestor type valve under the sink? I tried one of those years ago for a thudding washing machine and it made no difference so haven't used one since. The mains pressure seems fairly rubbish to be honest and he has not noticed any change in it.

What would you do/say/try?

Thanks

 

[ShaunCorbs]

I’ve had it before because there’s been a dead leg and it’s filled with air

Turn the mains off and open all the taps then turn the mains back on a bit and wait 5 mins ish

Go around the taps that are flowing and turn them off

Once all taps are flowing open the valve fully

 

[Last Plumber]

First of all, no I would not say it is your fault. Something has obviously happened but you only replaced a small section of pipe and valves are there for the obvious reasons.

It could be (as Shaun said), an air locked dead leg (which shouldn't be there anyway) or a lose stop tap jumper. Maybe mains if it is one or a stop tap to an outside tap? Check there are no draw off points in places that aren't used much e.g. out-houses, garage, utility room etc.

 

[Scott_D]

Is the pipe you touched clipped?
Touching anything where it passes through a hole?

 

[WaterTight]

I’ve had it before because there’s been a dead leg and it’s filled with air

Turn the mains off and open all the taps then turn the mains back on a bit and wait 5 mins ish

Go around the taps that are flowing and turn them off

Once all taps are flowing open the valve fully

Ok thanks, sounds worth a shot. What would you do/try next if you did that and it was still happening?

First of all, no I would not say it is your fault. Something has obviously happened but you only replaced a small section of pipe and valves are there for the obvious reasons.

It could be (as Shaun said), an air locked dead leg (which shouldn't be there anyway) or a lose stop tap jumper. Maybe mains if it is one or a stop tap to an outside tap? Check there are no draw off points in places that aren't used much e.g. out-houses, garage, utility room etc.

So I imagine if Shaun's suggestion of turning the mains on slowly and opening all taps, then turning them off didn't work you'd then explain something has happened but it can't be considered your fault, but offer to start looking elsewhere looking for valves/taps with jumpers but it would be chargeable yes? Is there anything else it could be or is it basically just those two? Air in a dead leg or loose jumpers in compression type valves/taps?

Is the pipe you touched clipped?
Touching anything where it passes through a hole?

It is yeah, they are all clipped. And then they disappear under the floor so no doubt something could be touching a hole but I wouldnt know without starting pulling the place apart

 

[Last Plumber]

Ok thanks, sounds worth a shot. What would you do/try next if you did that and it was still happening?



So I imagine if Shaun's suggestion of turning the mains on slowly and opening all taps, then turning them off didn't work you'd then explain something has happened but it can't be considered your fault, but offer to start looking elsewhere looking for valves/taps with jumpers but it would be chargeable yes? Is there anything else it could be or is it basically just those two? Air in a dead leg or loose jumpers in compression type valves/taps?



It is yeah, they are all clipped. And then they disappear under the floor so no doubt something could be touching a hole but I wouldnt know without starting pulling the place apart

This is one of those 'it was alright before you came', scenario's isn't it.
I would see if it was a quick fix and probably not bother charging in order to keep the customer but if it proves to be something more than air or a tweek of a tap, I would explain that it was going to be chargeable to find it and address it.