Strange Sort of Water Hammer

[roberta1000]

Still sorting my way around my new old house.

Latest oddity after the water was turned off during a new bathroom install is water hammer. But it is a bit weird - no problems when turning a tap off or flushing the loo or such but during the night (maybe other times too - don't know) there's a periodic bump every 20-30 seconds. Just a single bump. If I just crack the stopcock it goes away (but so does the water flow). Ideas?

(Electrician myself - electricity doesn't do funny things like this ;o)

 

[LUNAT]

HI

if possible change the stoptap

 

[roberta1000]

Oh dear! Usual plumber's location for this one (boxed in behind the kitchen units access for only 1 hand and no space to get a spanner. Plumbers are a special genetic pool designed for contortions in small spaces.

 

[ChrisR]

Blame the kitchen fitter, the cupboard wasn't there when the plumber put the tap in!

 

[Kes]

I doubt if it is the stoptap. Reducing the flow - with the stoptap - is alleviating the problem, the problem probably lies elsewhere. It sounds as if there is something that is attempting to shut off and is bouncing off the seating. why only one bump and what it is I haven't the faintest. Could even be next door.

If you 'crack' the stoptap for a while and then open it again does the bump reappear?

Most w/hammer probs are a combination of bouncing valves and long runs of unsupported pipes. And next door, of course.

 

[Slugbabydotcom]

Heres an idea or three

Latest oddity after the water was turned off during a new bathroom install

Theres your common denominator!

If your flushing valve is letting a trickle of water past it then the filling valve may operate to refill it. Everytime it reaches the mark it is closing off and causing the 'clunk' as the water stops flowing. Isolate the wc and see if it stops.

Less likely but yet to be ruled out is that it could be something to do with the mains supply. Your water could be provided from a pumping device on the water suppliers side that could be causing it. A shock arrestor should help if that is the case.

I have heard similar clunks from a thermal store 'operating normally'