Fog horn/groaning sound in pipes since irrigation put in

[JonLondon]

Until we has an irrigation system installed in September, we never had any disturbing sounds from our plumbing in the house we've lived in for 11 years. Since we put in the irrigation we get a periodic groaning sound from the pipes -- it sounds like a fog horn; loud and continuous (not pulsing) and lasting from a few seconds to 10 seconds.

At first I only heard the sound after running upstairs taps or toilets after the water had been off for a while (middle of night or first thing in the morning). But now it's getting more frequent, happening a few times each day and night, and it can happen even when there is no running water.

I have to suspect the installation of the irrigation has something to do with it as the sound first occurred after installation. To make the connection, the plumber made a t-connection to the main 3/4" copper line that run just below the joists in the basement; the connection is also less than a foot from a second connection to the main line that goes to an outdoor spigot --the spigot connection runs up from the mainline than turn 90 degrees towards an exterior wall while the connection to the irrigation runs straight from the main line, in the same plane, so to speak. The irrigation line itself is 1" wirsboro, about 30' that it appears well secure, that goes through an exterior wall and then up to a backflow detector before going down to the valves of the irrigation system.

I tried once to flush out what I thought might be air in the system but the sounds have persisted. The irrigation itself was shut down a couple of weeks ago (there's a shut off valve inside close to where the Wirsboro connects to the mainline) but the sound persists.

What may be wrong?

 

[tackleburger]

Most likely you have got grit in the pipe work try taking the ball valves and tap spindles off the offending appliances. If a check valve is fitted check that!!

 

[JonLondon]

tackleburger - thank for the suggestions! I'm not sure what the "offending appliances" may be. The sound used to only be heard when I ran the water when it had been off for a while but now it is heard even if no water is running. Where specifically should I look?.

 

[stevetheplumber]

tackleburger - thank for the suggestions! I'm not sure what the "offending appliances" may be. The sound used to only be heard when I ran the water when it had been off for a while but now it is heard even if no water is running. Where specifically should I look?.

look at any float operated valves

 

[Bernie2]

Its said that "water hammer" in one of its various forms can make a noise like a fog horn.

Its caused by suddenly stopping a flow of high pressure water. The thing is, it can sometimes set up what may better be described as vibration patterns rather than a bang like a hammer.
The shock waves can travel as fast as the speed of sound.

So getting things like ball valve or tap washers to vibrate at speed is relatively easy.

The thing is the resonance often makes them sound unrelated to what we may think of as water nosies.

But ball valves and taps are not the only things affected, loose pipework and virtually any other sort of water valve can be the cause as well.

Its a case of hunting the cause and as all systems are different its a bit hard to say exactly which component or components of a system the cause could be from, other than to give some general idea.