(2013-08-04) Home Lawn Irrigation System Whale Sounds

We had an irrigation system put in for our back-yard plant beds last summer. We never had any issues with it.

When we had new landscaping work done in the front this year, we added more segments to the system.

And a couple days that, we also had 1 of our water heaters replaced. The sounds started a few days later.

Ever since, we've had occasional issues with loud weird sounds coming from it. We first thought it sounded like a ghost special effect, but now I think of it as more of a "whale song". It doesn't happen every day. Some days it happens just once, some days more than once. It only happens during the period that the sprinkler system is running.

It's louder in the ground floor, esp in the kitchen. The backflow valve is right outside the kitchen.

I caught a bit of sound once while I was in the basement, and it was coming from up/out where the backflow valve is.

Though an earlier time I caught it outside standing near the backflow valve, and: no water was coming out of the valve (a sprinkler guy asked me to check that), and the noise didn't seem to be coming from right inside that. So maybe it's something else right in that area (where the pipes are still in the house or something).

I moved the sprinkler daily start time later so at least it wouldn't wake us up at 4am.

But I'd like to solve the real problem.

I've only found 2 pages online that refer to a whale sound.

• one got a totally generic "poor construction" answer.
• the other got a response categorizing this as a case of Water Hammer.
• this led me to search for "whale 'water hammer'"
  • one match said this wasn't really a water hammer, but more likely due to velocity noise as water flows past an obstruction (valve, tee, elbow or washer etc).
  • this post treats it as a water hammer, and suggests bleeding the air out of the chamber by shutting off the water then running the lowest faucets...
  • this says *It is not 'air in the system'. It is most likely a loose faucet washer or toilet fill valve washer. If it's just one fixture that makes the noise, you've found where to look... Water flowing over a loose washer can act like a reed in a saxophone - it can make a hellacious racket. *
  • [this](http://www.factsfacts.com/My Home Repair/PipeNoises.htm) page has a number of suggestions - see section with title starting with "Fog Horn": faucet washer; valve stem; high well water pressure, need pressure reducer;...
  • this says: quite similar to a loose washer on a valve