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gspck 11-24-2010 09:58 AM

Water hammer after replacing shut-off valves?
 
I just got around to replacing two leaky old shut off valves to our 2nd floor shower with 1/4 ball valves, and they seem to work great.. However, somehow it has begun some water hammering issues.. The hot and cold supply split at a tee at the shower and run to the toilet and bathroom sink. While turning the hot or cold off at the sink and/or toilet, I can hear the pipes shuddering fairly loudly. They also seem to knock when turning only the cold supply ON, again at the sink or toilet.. No issues whatsoever with the shower, or the plumbing in the rest of the house, it just seems to have affected everything after the shower. I've looked for air chambers in the wall, can't find anything.. The weird thing is that the problem disappears when the new shower shut offs are closed.. I have spoken with a plumber and he seems confounded and doesn't think the valves could have caused this, but we have never had any issues before this? Anyone have any ideas about this?

SDC 11-24-2010 10:34 AM

1 Attachment(s)
check to be sure all straps (fastening to the studs) are tight. Pipes will move when turned off and on, look at a garden hose while doing the same. Make sure you have placed enough pipe clamps/straps and they are all tight.

Attachment 27116

hyunelan2 11-24-2010 10:59 AM

Do you have air columns or hammer arrestors in place on the pipes? When you removed the old valve you didn't per chance cut off the old air column with it, did you?

moopey 11-24-2010 11:38 AM

as the previous post mentions adding water hammer arrestors could ease the problem.

if you didn't have the issue before the valve install, i would think the valves are an issue. unless its a typo, 1/4" is really small for any plumbing fixture. Are the pipes 1/4" or did you install a 1/4" ball valve on a 1/2" pipe?

Homerepairguy 11-24-2010 12:02 PM

Quote:

Originally Posted by moopey (Post 539984)
if you didn't have the issue before the valve install, i would think the valves are an issue. unless its a typo, 1/4" is really small for any plumbing fixture. Are the pipes 1/4" or did you install a 1/4" ball valve on a 1/2" pipe?

I think what he meant is quarter turn ball valves.

gspck 11-24-2010 12:32 PM

The original valves were the only thing removed.. And yes, I meant to say 1/4 turn ball valves.. On 1/2 copper pipe. Most of the offending plumbing is visible from below at the moment. There is a short section that is obstructed that could, I suppose, contain air chambers.. There are no water hammer arrestors currently. Now I'm thinking of having them added, but it still seems odd to me that any movement of the pipes goes away when the shower shut offs are closed.. Seems like a band-aid fix. As far as I know, there's not much in the way of strapping. Maybe I jostled the pipes a little loose when working on them? Or somehow I affected the water pressure? Beforehand the pipes were SILENT, no knocking or hammering or anything..

Homerepairguy 11-24-2010 01:24 PM

Quote:

Originally Posted by gspck (Post 540004)
Maybe I jostled the pipes a little loose when working on them? Or somehow I affected the water pressure? Beforehand the pipes were SILENT, no knocking or hammering or anything..

Ball valves are straight through, about full diameter flow. If your old valves were gate valves, the water path was more convoluted. So maybe the flow velocity with the ball valves is just a bit faster now, which is enough to cause your new problems.

As an experiment, maybe try shutting off the ball valves part way and see if the problem goes away.

gspck 11-24-2010 01:42 PM

I have tried shutting the valves partly and the only point at which the hammering stops is the point where the flow is so restricted to the shower that there is barely enough pressure for the water to trickle out.

the_man 11-24-2010 08:55 PM

try turning off the angle stops on the toilets. the diaphragm inside the fill valve can vibrate and make that noise. Also, do you have a prv (pressure reducing valve) if you do tighten the screw/nut on the top a little bit and see if it stops.


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