I've got a perplexing sprinkler system problem and would be grateful
for any advice. The overall situation: underground sprinkler system
is in a new house but was probably installed on the cheap (the seller
is no help). I'm converting everything to a drip system.
The main problem: one zone continues to run 24/7, much more than a
leak, closer to normal operating pressure. This happens any time the
gate valve from the water main to the sprinkler system is open. When
the normal 7-zone cycle is run, the zone turns on like the rest, but
continues to flow forever after it's supposed to shut off. The only
way I've been able to stop the flow is to secure the whole system by
turning off the water supply (the gate valve). I believe this problem
has existed for a long time, since I recall seeing leaks when I was
repairing some broken heads in that zone (I figured they'd eventually
Things I've tried to no avail:
1) Installed a regulator for the whole H2O system at 50psi.
2) Purged valve (Irritrol model 205TF) using external port.
3) Cleaned out solenoid seat.
4) Opened valve cover, checked diaphragm. No apparent problems, valve
completely clean, diaphragm perfect.
5) Replaced solenoid with a new one.
6) Disconnected both solenoid leads. Expected valve to close, but
water continues to run as before.
7) At the control box, connected the valve wires to an unused Zone 8.
8) Connected the solenoid wires to those for the valve adjacent to it
in the in-ground box and switched the wiring in the control box
accordingly (effectively using a known "good valve's" wiring).
9) Swapped out the valve in question with a completely new valve (the
identical valve, only it has been rebranded model 2500TF).
The water has continued to flow in all cases, any time the water
supply is on. I've about reached the end of my rope. Any ideas to
solve this problem will be much appreciated. Thank you for reading.