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I had a kind of similar situation; Kind of because only 2 of 6 zones made the clanging. First, I tried to look at the backflow, but it checked out fine. Then I reduced the flow, but thought the same thing it should be able to handle it. I ended up going to the master valves and changing the diaphragm, it helped a little. Then I went to the two problem zones and changed the diaphragms and the problem was fixed. It is odd to have that many that need to be changed at once, but odd things happen.
Can't explain the neighbor situation either unless you both have old or inferior valves. Maybe your water is really tough on irrigation materials.
Good Luck
If you can go to the street and shut off your water at the curb, you could then cut out and replace the old stop&waste valve upstream of your water meter with a ball valve, and gain improved performance.
But before you go to extremes like that, you are going to replace one of your zone valves with one that has a flow control - hopefully you can do this by simply switching bonnets.
What is the total distance from the street to the zone valves?
This post has been edited 1 times, last edit by "brisk" (Jul 13th 2011, 12:07pm)
150 feet of 3/4-inch copper is a considerable source of pressure loss. When I have a home that's 100 feet from the street, I know I have concerns about pressure lost in the supply line. Don't worry about the double check valve assembly - it is a non-issue. Try a PGV bonnet with a flow control. Try reducing flow in one of the banging zones.
Another possibility for reducing the initial rush of water into a zone, is to have all check-valve heads.
Your pressure measurements don't mean squat when the valve opens, because the losses caused by the initial rush of water into the zone is what sets up the oscillation.
150 feet of 3/4-inch copper is a considerable source of pressure loss. When I have a home that's 100 feet from the street, I know I have concerns about pressure lost in the supply line. Don't worry about the double check valve assembly - it is a non-issue. Try a PGV bonnet with a flow control. Try reducing flow in one of the banging zones.
Another possibility for reducing the initial rush of water into a zone, is to have all check-valve heads.
You can't reproduce the effect in your home, because there isn't a diaphragm valve maxing out the supply. Get to work on the given solutions and stop asking questions.
This post has been edited 1 times, last edit by "brisk" (Jul 14th 2011, 2:00pm)