knocking cold water pipes

did you try here?

http://en.wikipedia.org/wiki/Water_hammer

http://home.howstuffworks.com/how-to-fix-pipes5.htm

calculator:

http://www.lmnoeng.com/WaterHammer/WaterHammer.htm

http://www.plumbingsupply.com/waterhammerarresters.html

have at it.

milo

Milo,

The time I had that problem I found that the pipes were not properly secured with clamps. That was about twenty years ago with this house I am in now. I don't remember having to rip out any sheet rock to fix it.

The one symptom I do remember is that if I opened the tap involved slowly there was no problem.

Hope this helps.

There must be some obstruction in the inlet of the flow, When you open the tap, the sudden drop of outlet pressure on the other side of the Nozzle must be creating the water hammer.

Check up the pipe line - might have heavily rusted/ clogged/ scaled (cholesterol coated -if pipes can have it and is on the point of heart attack- the thumpings are - as I get it the humps on the ECG on the jogger)

Why dont you try to de=scale them ?

Hi edigan

Same reply as I was going to give, only said much better. GA for that.

Why thanks!

my last house had mains pressure at 125PSI.

Shower would knock you flat, and I could water the neighbor's neighbor's lawn with my hose, but went through a lot of seals and washers! And you learned never to leave the hose pressurized.

How is life down there? Financial meltdown truly global yet?

Pipe clips, to stop them thrashing around when the flowrate in the pipe changes: Newton's laws say that they will, given no restraint. Check out any major home improvement outlet - there are a number on-line, for example, and the purchase price will not break the household budget...

Hello Guest,

I have had to deal with this a lot, and found the likely cause was the Plumbers had not used enough pipe clips. I found 9ft (~3 Metre) with no clips. The pipe in my case was knocking the plywood casing of the box covering the pipes.

Hammering is something different. I think it caused by a valve in a stop cock, tap, or ball valve not seating properly, it does not go up-down like it should. But the piston moves and comes down one edge first and so it gets wedged. It keeps 'hammering' because it cannot either turn the flow on or off. A large bath tap or a mains cold water tap might stop it if turned on fully. I have heard it in new houses so I do not 'know' what it is, this is just what I think it is.

You can sometimes stop the thump as a tap is turned on or off, by easing the stop cock a quarter turn, then another and another. But I would not turn the stop cock more than 360 degrees or one full turn .

Hope that is not too confusing.............And help?

Take care..............happy new year..............

thanks for everones response. it turns out the pipes were simply not properly secured to the walls. it took me a few minutes and cost me nothing to fix the problem! thanks again!