Water Hammer Problems

Can you help?

Last year I had a lot of work on the house plumbing: new bathroom and a water softener added, all functioning fine. However since the work was carried out I have had an irregular pipe noise. It happens the morning after the water softener has regenerated (which happens at 2am). When the water is run for first time eg toilet flush or shower and the mains riser starts to fill the cold tank, a loud clunking / knocking noise emanates from the riser pipe and ballcock as the ballcock tries to close off the water to the cold tank.

After a few minutes it will stop and not happen again until the water softener regenerates. The plumber who fitted the bathroom and softener tried to resolve by refitting the cold tank ballcock (old one was pretty scaled up) to no avail. He didn't really have any other ideas after that.

My usual heating system plumber (not the one who fitted the softener) fitted a Shock Arrester a few weeks ago. This does make the problem a bit better - ie. when it happens it lasts a shorter time - but has not eliminated it altogether.

The shock arrester was fitted right by the mains stop cock quite a long way from the ballcock - could that be a reason it did not work completely?

Also the local plumbing suppliers suggested fitting an equilibrium ball valve. Has anyone resolved water hammer with one of these?

Any suggestions welcome

Many thanks Iain

Water shock arrestors are normally fitted as close as is possible to the appliance believed to be causing the problem. In this case it could be your ball valve or it could be your water softener. I'd go for it being the ball valve.

An equilibrium BV may help, or it may just change the noise you get from judder to a thump

try turning the isolater down if its just to the toilet so ristricts the flow water to the toilet