wrote in message
ups.com...
This is the type of valve found on irrigation systems (24V ac). Is it
normal for them to buzz (loudly). I'm guessing not, maybe a slight hum
but not a loud buzz.

Other replies relate to solenoid chatter. This may very well be the nature
of the problem. However, I recently installed a new valve assembly in the
brass valve body and got a high pitched buzz whenever the valve was
actuated. I turned out that this was the result of restricting the flow by
manually closing the valve too far. The diaphragm which restricts the flow
(about 1" in diameter) is backed up by a spring and the two were resonating.
Backing off on the manual closure ended the problem.

Since our mains pressure here is about 95#, I was trying to minimize the
stress on some old plastic piping. Apparently, I just got more pressure
differential across the valve than the design could accommodate.

SJF