Hammer Tap Arrestor Not Working - Help Needed!!! All aspects of plumbing questions and answers, help, tips and information

[jessisinthegarden]

We have had hammer tap bothering us and the upper maisonette above us for several months. next door have the same problem. Thames Water not interested in this coincidence and are claiming that even if their pressure has increased, thus probably causing the hammer tap to 4 maisonettes, they won't help us fix it.
We've bought our own hammer tap arrestor and fitted it today - it seems to be leaking a little though (about 2 drops/minute) and our plumber's coming to have a look soon.
But what really worries us is that in spite of being now connected in our toilet cistern, the hammer tap is still very much present.
Where have we gone wrong?

[proptech]

I have to start by asking precisely what form this hammer takes, is it one sudden bang, or a series of noises.
Also the plumbing layout of the properties, have you storage tanks, or is everything off the main ?
Where have you fitted the arrester ?
There could be many reasons, if there are tanks, the ball valve would be the usual cause.

[jessisinthegarden]

Thanks for your reply.
Hope I can answer all your questions back.
Two maisonettes, 2 floors each (ours is lower and raised ground floors).
No storage tanks in either.
Both have combi boilers and everything coming off the mains, yes.
Arrester fitted inside toilet cistern in our bathroom on basement level (closest point to our stopcock, apparently).
The noise itself: heard only at the very end of the cistern filling or just at the point a tap is turned off (particularly if turned off quickly) and is a series of a few short bangs, like a shudder, getting quieter as they progress.
Thanks for any advice in advance.

[proptech]

Thanks for the feedback.
It does make things more difficult there being 2 properties involved. There could be many reasons for this problem. It's basically a shock wave from the supply being stopped quickly. The wave will travel back and forth until dissipated.

I can only suggest some of the causes.
Pipework not correctly supported/clipped in position.
Loose washers/jumpers in stop cocks.
Stop cocks only partially open.
Defective float valves in toilet cisterns.
A 'dead leg' left in the pipework after an alteration.
A garden hose connected with the outside tap still open.
Excessive water pressure.

I've no idea what the device is you've fitted, but inside the cistern is hardly likely to do anything. A proper arrester would have to be fitted in the supply, close to the cause of the problem.

Can I suggest that you fully close the stop cock of one of the properties, try the supply, and repeat with the other in an attempt to narrow down the cause. If all else fails, the fitting of an arrester in the supply may help, but there are no guarantees.