Question
my sprinkler system won't come on. if i flush a few toilets and runa couple sinks... then it will turn on. I replaced the PVB, because i thought might be the problem.  The New PVB does the same thing. Now I turn on the timer, manually starting the first zone. Then i walk to the PVB, turn off both top and bottom valves on the PVB and release the pressure on the drain nozzles. Then if I turn on the valves, the zones begin and will run through the cycle.  If i turn off the system in mid zone, it won't come back on unless I do the same "start-up" procedure.
HELP!

Answer
This is really confusing me.  Is the PVB perhaps installed backwards?  Or perhaps it is too large for the flow of your system?  It almost sounds like it has some back pressure on it, maybe from the house plumbing.  I will do a little more investigation on this one.