All valves stuck in open position
I have a system with eight circuits in the front yard (WeatherMatic 12000 series valves, installed 2003) and seven circuits in the back (30-year old valves). My system runs off a water well, with VERY hard water - it leaves white deposits on everything.
Last fall I started having trouble with all the WeatherMatic valves opening at the same time when the system turned on - no matter what valve was selected. That trouble continues this spring.
The problem isn't the controller. It only puts out voltage on one circuit at a time. With the controller completely shut off, if I turn on the well it get a dribble of water out of all the front valves. The older valves in the back yard seem to be working fine.
I opened up one of the WeatherMatic 12000 series valves to see how bad it looked on the inside. Actually it wasn't as bad as I thought it would be given the condition of my water, but the diaphragm is covered with a yellow pasty film. Otherwise, it didn't appear to be damaged.
I need suggestions on how to trouble-shoot this problem. Is it feasible to change out the "guts" of a vale, without having to remove the valves from the piping - that would be a real chore? Any suggestions would be appreciated.