Valve Nightmare Please Help
I will give as much background as I can because I'm still not 100% sure what's wrong. I've been the owner of the house for 3 summers. I had not problems the first 2 summers. The water main comes into my house via crawlspace and it immediately bisects. One pipe goes to my sprinkler system the other to a water softener that services the house. I have 10 zones. One manifold and irrigation box contains 4 valves, then there is a box with a single valve (I think they got lazy) and finally I have a 3rd box with 5 valves. The valves are Hunter PGV (square with screws, NOT the twist off kind) It's the furthest box with 5 zones where my issues seem to be centered.
This last winter there was a main pipe that broke in the alley and effected my house and my neighbor's house. They repaired it but I believe it got some sand and gravel into my lines. I've noticed no issues inside the house but my water softener has a filter. However, I've had nothing but trouble with my sprinklers in the spring.
First thing I noticed was that I couldn't operate the system via the control box. First zone came up fine. But when I transitioned to the 2nd zone, the 1st zone popped down and the 2nd zone came up at 50% power. I transitioned to the 3rd zone and the all sprinklers popped down. I figured the valves must be stuck open. So I opened up my valves and cleaned the diaphragms. They were a bit slimy but only a few very, very small pieces of sand were found. I put it all back together but still no luck. If I put my ear down to the control box I could hear a hiss. I was able to water my yard by manually opening each zone but sometimes using the selenoid wasn't enough. I had to use the bleeder screw sometimes. However I wasn't getting full coverage because zones 1 and 2 would stick slightly open and cause me to not have full pressure. I also had about 6 heads sticking. I dug up the heads completely and cleaned them out (they were loaded with sand) and that is no longer an issue. I had to turn the bleeder screw to open/close. And even after closing manually I could hear a slight "hiss" coming from near the valves (I can never pinpoint which one exactly as there is no leakage... just a hisssss sound like water is still flowing).
I didn't have an valve replacement parts but I finally figured out zone 2 wasn't shutting all the way off. I could pull up a head in that zone and a very slight trickle was coming out. So my dad came down with some parts for sprinklers. All I did was change the diaphragm in zone 2 and viola! My system roared to life. FULL POWER! and everything even worked from my control box. The key thing for me was that when I put my ear down into the valve box I could hear nothing but silence!
I thought that was the end of it. It worked for about 3 days then one night I noticed my sprinklers were REALLY weak. Zone 1 was sticking open. I replaced the diaphragm and again it worked! However, after a couple of days Zone 3 was now not shutting fully off. This was a bit tricky to discover because Zone 3 is up hill from the manifold. There was a puddle around one head on zone 3 that would never go away. I changed the diaphragm and spring in zone 3 but no luck. There is still a slight "hissss". I also tried replacing the selenoid and still that hiss won't go away. I don't see any sand or gravel in the line.
On Monday I'm have a guy come and install a filter at the main entry line for my sprinklers. I am considering hiring him to replace all the valves with Hunter PGV jartops unless there is a better valve that might not be so finicky when it comes to a wee bit of sand? I'm also not convinced that replacing all the valves in that box will fix my issues. I am getting weaker pressure again and I'm back to manually tweaking them as the control box won't cut it.
I had thought I might have a leak in the line but since my sprinklers have worked properly for at least a few days when I hear no "hiss" in the valve box, and since I hear that "hisss" in the valve box when things aren't working I'm pretty sure it's a valve that's only closing partially... I am at my wits end and would greatly appreciate any help at all. Is there anything I could do that I haven't tried?