noise under house after irrigation system shuts off

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plumbingdummy

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Hi all,

I have an irrigation system that runs in the middle of the night. Starting several nights ago, right after the system comes to the end of its run with a sprinkler in the back yard, I hear a low rumbling/rattling/vibrating/pulsating type noise that I believe is coming from under the house. The first time that I paid attention to it, it lasted for about 5 minutes. Last night the same thing occurred, but several minutes after it had stopped, it started up again. I got it to stop by shutting off the entire water supply. When I turned the water supply on again this morning, that noise did not start up again.

The main supply pipe comes into the one-story house below the bathroom. Just inside the foundation a branch goes off to the front yard irrigation. Somewhere else under the house another branch goes off to the back yard irrigation.

Where I hear the noise the loudest, is in the bathroom--even louder then when I am outside right next to where the main supply pipe enters the house.

The irrigation run starts with two successive zones in the front yard, and ends with three successive zones in the back yard.

It may be that whatever is causing this new noise that I hear after the irrigation system is done has actually started during the irrigation run--but the normal irrigation run noise is so loud that it would be masked.

Does anybody have any idea what could be going on?

Could this have anything to do with siphoning from the irrigation system? (Although I do have anti-siphon valves.)
 
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Yes! It's just beyond the main shut-off valve. It was put on a few years ago to reduce the pressure to 50 lbs. from over 70--to protect the irrigation system.
I bought it myself--got the best one the store had, and the plumber who installed it said it was the best.
 
If the pressure reducing valve is the problem, what exactly is going on that causes that noise? And why would it happen only when the irrigation system finishes its run?

The valve was Watts brand, cost $66, and was installed only 5 years ago.
 
If it's not the PRV it might be a zone valve (solenoid) or backflow. You need to do a process of elimination. Isolate the sprinkler system from the house by turning off the sprinkler system main water valve. Use water in house for a day to verify that no noise is present when water is used in home. After House test turn on sprinkler main water valve and turn off house main water valve to test the sprinkler system. Test sprinkler system by turning each zone on manually.

(The way you describe the design of the sprinkler system sounds a bit different. System are usually piped from one trunk line if it was installed by a company, not from the front & back of the house piping. Are you using hose bibb/hydrant to operate the sprinkler system ?)
 
The irrigation system is controlled by an automatic timer, but I can test each zone individually as you described--except there is no turn-off valve for just the house by itself.

It was installed by a DIY-er--many years before I came here.

There are 5 zones, a mixture of sprinkler and drip, but only two turn-off valves (front and back yards)--besides the main turn-off for the whole water system.
 
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phishfood, IFIXH2O, and anyone else:

I've been experimenting, and was able to reproduce the noise. I ran the backyard sprinkler by itself tonight. When the remotely-controlled valve shut off, it was entirely normal--no chattering or noise of any kind. I immediately went into the bathroom, and the noise was going on. (The bathroom is right over where the main comes into the house, and further on under the house is where a branch goes off to the backyard irrigation.) I went outside to where the main enters the house, and out there the noise sounds like rattling just inside the wall. While this was going on I went back to the sprinkler valve twice, and nothing was going on there, even with my ear right on the valve. After maybe 10-15 minutes the noise in the bathroom got more irregular and louder. And when I flushed the toilet it stopped!

I also ran the four other irrigation zones separately, and the only thing of note was that the valve for one drip zone chattered for a few seconds at shut-off, and the valve for another drip zone chattered for a few minutes--but there was no noise in the bathroom.

The pressure-reducing valve, a brass Watts 25AUB-Z3 installed five years ago, is still doing its job. When installed it was set at 55 psi (not 50 as I said in an earlier post), and that's the reading I'm getting now. phishfood, do you still think that could be the problem? It's very close to where the noise seems to be coming from. Could it be that the PRV filter needs cleaning? Some work was done on the branch to the front irrigation a couple of years ago that caused dirt to get in, but that was down-stream from the PRV.
 
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PD, some plumbing problems need a plumber on site to troubleshoot because of the different process elminations we use and actually seeing or hearing the problem. Phishfood might be right, it may very well be your PRV. Try one more thing. Create the noise again and turn the water off to the toilet instead of flushing. I have seen where water moves then stop causing the toilet fill valve to give off the noises you describe.
 
regulators are only good for 3-5 years. i would make sure the piping is strapped properly and start with the reg. also make sure shut-off valve is open all the way if it not a ball valve. a half closed valve will cause turbulence in the line.
 
Thanks, IFIXH2O and journeyman.

Before reading your posts, I ran another test, hooking the hose-end backyard sprinkler up to the hose bibb right next to the irrigation valve it is usually connected to, and when I shut it off, the noise in the pipe below the bathroom did not occur. (Unless it stopped in the few seconds it took me to get into the bathroom; but previously it has gone on much longer.)

IFIXH20: I tried twice to test your idea of turning off the toilet water, with the sprinkler hooked up to the irrigation valve, but the noise did not occur. I ran it for only 5, and then 10 minutes, rather than the usual 40 minutes, as we have a severe drought situation here. Would that make a difference?

journeyman: Are you saying that the pressure regulator could be shot even though the pressure is still being reduced from 70-80 down to 55, which is where it was set upon installation?

I'm sure the shut-off valve is open all the way. The handle is the lever type, and it comes to a definite stop in the vertical position.

So far: the noise has occurred in only 1 out of 4 tests via the irrigation valve, after a 40-minute run. (Negative tests were 5 min., 10 min. & 40 min.)

What are the likely consequences if I do nothing further about this, except stop the noise whenever I discover it, which means it could go on for hours--
or days if I'm away on a trip.
 
If the integrity of the piping is weak in any spot the rattling, hammer, vibration can cause that area to give way. So yes, the problem can pose a issue.
 
proper way to test a reg is to do a running test. if it drops 15 psi or more the reg is not working properly. hook up gauge and turn water on it see the pressure drop.
 
journeyman,

I did your test of the pressure regulator. I wasn't sure where I should turn on the water, so I did it two ways, with the pressure gauge on the back hose bibb.

Water turned on at kitchen sink full force:
pressure gauge: 57 psi to 47 psi.

Water turned on at irrigation valve (connected to hose) next to pressure gauge:
54 psi down to 17 psi--then back up to > 60 psi when water turned off.

Very different results! Which is correct?
 
it is still dropping you should only loose 5 psi when a fixture is turned on. i would start with reg. that is a big drop when the irrigation was turned on can you post a pic of your reg and irrigation set up
 
journeyman:

Here's a photo of the PRV which is right after the main shut-off valve, just before the supply pipe goes under the house.

http://www.watts.com/pages/_products_details.asp?pid=776

FOR THE IRRIGATION SET-UP, SEE THE DIAGRAM IN THE ATTACHMENT AT THE BOTTOM OF THIS POST.

Pipe extends out from near kitchen sink to back irrigation manifold approx. 20 -25 ft. away. Pipe could be longer.

A - shut-off valve

B - anti-siphon valve --> Y filter --> 20 psi pressure reducer --> drip system

C - same as B

D - hose bibb (where I test the pressure)

E - inactive anti-siphon valve connected to in-ground sprinkler system
which broke down years ago (lack of pressure)

F - anti-siphon valve --> hose bibb -->hose --> moveable sprinkler.

Test where psi went from 57 to 47: I turned on kitchen faucet full force.

Test where psi went from 54 to 17: I turned on F, but sprinkler was not attached.

photo of anti-siphon valve:
http://www.amazon.com/dp/B00085E6RK/?tag=skimlinks_replacement-20

DIAGRAM OF IRRIGATION MANIFOLD:

View attachment irrig. manifold.pdf
 
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