If you can add a tank or piece of pipe vertically, in front of the valves,
you can reduce the effects of water hammer. High water pressure is the
culprit. I work with ice machines that have this same problem. The mfg.
changes vendors on valves and all of the sudden you have these noises. The
idea behind the tank or length of vertical pipe, is that all water pipes
have a little air in them. If you can trap a little of this air, you can
create a shock absorber (so to speak) th reduce but probalbly not stop the
hammering. This will also let the valves last longer and is most likely what
caused the old valves to fail. When I built my house, I installed a 1'
length of 1" copper pipe w/ a cap, on each cold and hot faucet supply line.
I tee'd them into the supply line inside the wall and added a enough
standard pipe to make sure they 1" pipe would be higher than any fixture
they were serving. PVC pipe would work for your application. Follow pressure
glueing info.
Good luck Lyndell

P.S. If there is a lot of construction in your area, the water company has
been forced to increase pressure to keep up with demand. I forgot to mention
that a water pressure regulating valve (inlet side of the valves) would also
do the trick.


"Mel" wrote in message
...
I recently replaced the solenoids on my two Lawn Genie automatic
anti-siphon lawn sprinkler valves and now there is water hammer when they
shut off. They come on go off individually, back to back. I've had the
valves for several years and this is the time I've replaced the solenoids.
Is there a fix for the water hammer?