Water hammer?? Possibly??

[GreenArmy]

Im On-Call this week and ive just got back from a house complaining of an air lock.
To cut a long story short....
A noise in house like a Brrrrr that lasts for 2 seconds and goes Brrr again every 20 seconds. Not that loud but annoying for tenant.
First thing i think is the ball valve in tank or wcc.
Cistern ball valve Ok and combi fitted so no tank. Turn off cold supply to boiler still noise. No sign of any leak in property. No water running. Standard taps on everything. So i tell tenant not sure what it is and the fact im emergency call out and ive been working since 8am that im not going to hang around all night to investigate any more. Then i decide to quickly turn off the internal stopcock and see what happens. Noise stops. Left tenant with water off so they can can sleep without annoying noise all night and to phone again tomorrow or Monday when we can have a fresh mind and time to investigate. Im sure its probably something straight forward (possibly washer/jumper in stop-cock? but why when no water running or something)
Any ideas gang?

 

[REDSAW]

proberbly heating pipes then?

 

[PLUMB111]

Ive had the same problem in a property, and it turned out to be the Torbeck Valve in the WC cisturn.

 

[GreenArmy]

mmm, heating wasnt on (hadnt been used all day and no drop/increase on pressure). Standard ball-cock in cistern.
I doubt i'll go back to this as it will probably go to day-to-day repairs on Monday and someone else will get it. I will try to find out what it is when it gets done though, just for future reference.
It just goes to show that even with 19 years experience working as a plumber in council houses that i dont know it all.

 

[Puddle]

If not a internal filling loop which would have been isolated when you isolated the boiler,I will go for the tenant messing about with the filling loop for the boiler and not turning it of fully,presure build up the Presure release valve opens making Brrr sound,lowers presure and closes ect

 

[dick999]

I agree with puddle, check the filling loop if it is shut properly.

 

[GreenArmy]

I agree with puddle, check the filling loop if it is shut properly.

Got to admit i was only there for quarter of an hour late last night and the boiler was steady at 1.3
Obviously if i was there now i would spend more time on investigation. But there was certainly no obvious signs on any of the plumbing.

 

[justlead1]

Hi Mark
I could be as simple as the stopcock being turn off for some reason by tenant and when turned back on, opened further than before. Just crack it open until the kitchen tap is at sufficient flow and monitor results. Good Luck

 

[dick999]

Hmmm....strange!!! must be the chap upstairs, must had a huge curry!!! letting off every 20 mins...

 

[Bernie2]

Hmm

Could be as you said washer in stopcock.

If the internal plumbing seems okay, how about something on the water company mains supply causing the house stopcock washer to vibrate with water hammer?

Most internal main stop cocks, have loose jumpers which are supposed to act as a none return valve, that means they could perhaps vibrate if the cause was coming from not only inside the house, but also outside.

It may be the water companies stop tap out in the street. That is of course providing it is a screw down valve and not a plug cock.

Turn the house stopcock on and the outside one off to find out what happens.

Unrelated tip:

Water hammer:

If you have a plastic storage cistern with a copper feed to it. Make sure all the plates are fitted to the ball valve to help make it more rigid and that the last metre or so of the supply pipe is plastic.

It's an old trick.

 

[Mike Jackson]

I've had this in the past with double check valves. You'll find that some house builders fit them to the cold main just after the stop tap and to the washing machine cold feed due to over zealous water inspectors not understanding the regulations.

Mike

 

[david williams]

went to one like this in bromley kent finaly traced noise to clients burgaler alarm manfunction