Cold Water Hammer

cheers Sid - because it is not happening in any other house on my street I believe it is sthing to do with the tap so i'll give the washers a try first

Squidster, the font of all knowledge for anything that's mechanical

Originally Posted by Sid Squid

Generally it's down to insufficient pipe support, it can be worsened by ceramic disc taps - they shut quite abruptly and cause the quick static pressure rise that sometimes causes the hammer in pipework that can move.

If the pipes can't be suitably fixed, there are devices that can be fitted to the incoming main to reduce hammer, essentially they're in two forms:
1) A pressure reducing balanced valve, like the regulator on a gas bottle or a DV if you're a diver, (Jaques Cousteau apparently used a modified camping gas regulator for his first experiments in Scuba breathing apparatus).
2) A piston in a pipe with a spring behind it, when the pressure rises as a valve is shut the piston displaces and the slows the static pressure rise.

Originally Posted by Sid Squid

Generally it's down to insufficient pipe support, it can be worsened by ceramic disc taps - they shut quite abruptly and cause the quick static pressure rise that sometimes causes the hammer in pipework that can move.

If the pipes can't be suitably fixed, there are devices that can be fitted to the incoming main to reduce hammer, essentially they're in two forms:
1) A pressure reducing balanced valve, like the regulator on a gas bottle or a DV if you're a diver, (Jaques Cousteau apparently used a modified camping gas regulator for his first experiments in Scuba breathing apparatus).
2) A piston in a pipe with a spring behind it, when the pressure rises as a valve is shut the piston displaces and the slows the static pressure rise.

Alternativly, take a "T" off the cold water supply and connect it to a 80 foot pipe that sticks straight up in the air

But on second thoughts Sids idea is tidier

Originally Posted by Tris

Alternativly, take a "T" off the cold water supply and connect it to a 80 foot pipe that sticks straight up in the air

Great idea! But what happens when the reservoir is more than 80' above you? Mmmm...

[embee]

If all else fails with the tap, you may need a shock arrestor, especially if the tap is at the end of a long pipe run. Sometimes just a different type of tap design with the pipework you have will cause the jumper to vibrate, it happens.

Something like a Watts Micron Shock Arrestor, http://www.lunns.net/ , usually around £20 inc. might do the trick.

Washing machines etc are usual culprits for causing a shock with a sudden shut off.

If it's a vibration then it's often inadequate pipe supports.