SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

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?

Thanks Wet_Boots. Unfortunately this evening I found the offending valve and now have no "hissss". Every time I've cured the hiss the sprinklers have roared to live. But now all is quiet in the valve box and the sprinklers are still running at low pressure. Everyone I've asked has just shrugged and said they have no clue how to help me. I haven't noticed in drop in pressure in my house at all. What could be causing this? One suggestion I had was that the back flow mechanism that is directly after my sprinkler main line has a bunch of sand in it. But the city told me that all the sand I would have gotten in the system would already be in there due to the pressurized line. Any thoughts on why I wouldn't be getting full pressure through my lines now that I have all the valves closing fully? This is frustrating because nobody can tell me how to properly troubleshoot this now. I'm hoping the guy coming out Monday will have some solutions.