Severe Continuous Pipe Vibration When Valve(s) Open
I've wrote this up several times and tried to be brief and concise but it seems to get longer and longer because there are so many ifs. I hope this boiled down version paints the picture. I have studied this intensely on the internet, tried lots of combinations of things, spent many hours messing with it. Any and all ideas welcome. :-)
Copper pipe under house vibrated SEVERLY. Shook the house, rattled the dishes in the cupboards. This was not a couple bangs like water hammer it is continuous like a jack hammer. It does not stop until I flush a toilet or sometimes open a hose bib for a minute or less.
It only happens when valve(s) open.
Only with opening of these valves; sprinkler mostly, toilet & washing machine rarely. Inside faucets do not initiate vibration.
After reducing pressure from about 120 psi to about 50 psi (installed a PRV) the problem is reduced to this: Intensity of vibration vastly reduced.
There are 17 sprinkler valves. Any one may or may not trigger the vibration. The house was built in 1981 and the sprinkler systems installed mostly in 1982. Some valves have never been replaced. There wasn't a peep from the pipes till this summer.
The sprinkler circuits T off the main line upstream from the main house. The vibrating pipe doesn't even have water flowing thru it. The pipe is all PVC up to the house where it transits to 3/4 copper.
My conclusions are:
1. High pressure by itself is not the problem.
2. Loose pipes are not the problem.
3. Something obviously changed but what I cannot imagine.
4. Air in the pipes must be the prime problem.