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I have a line with a long downhill run and a 100-DS valve at the top. When power is removed the valve doesn't close. I called the 1800RAINBIRD line and he confirmed my guess that negative pressure is preventing the line from closing. He offered no advice. Anyway, being an engineer, I could design a circuit with another valve that would open momentarily when power is removed to break the suction long enough to let the valve close but hoped there might be a ready made solution. I thought maybe it would be possible to increade the spring tension in the valve to help it close better. Please don't tell me I am an idiot for designing and installing my own system and making a simple mistake. The Rainbird hotline guy already did that.

PS - I am fully prepared to replace the valve with a different/better one if necessary.



Edited by - tmostad on Jun 30 2003 6:17:44 PM

Thanks for the responses.

The negative pressure is never relieved, i.e. the water in the line apparently keeps the valve open by suction which releases more water which keeps the valve open, etc. and the valve never closes (water continued to flow overnight after power was removed). I thought about putting a drain valve in-line right after the 100-DS but wasn't sure how the dynamic would work. I think the suction might pull it open and allow air into the line breaking the suction. I will try this if all else fails.

The valve is *far* above the highest sprinkler, about 60 feet.

I know the valve is fully closed, i.e. turn so it is not manually on. There is no leakage at the valve therefore I don't think the bleeder valve is open but will check. I have 15 other valves in the system and none exhibit this behavior but also none of them are in this uniques situation. I will diassemble the valve and clean it/check the diaphrams and screens.

The guy at Rainbird was emphatic that I had made a grave mistake and implied I should have hired a contractor to do the work and was really stupid for not having done so. It was really a quite amazing conversation.

Thanks again for the suggestions.

Thanks for the responses.

The negative pressure is never relieved, i.e. the water in the line apparently keeps the valve open by suction which releases more water which keeps the valve open, etc. and the valve never closes (water continued to flow overnight after power was removed). I thought about putting a drain valve in-line right after the 100-DS but wasn't sure how the dynamic would work. I think the suction might pull it open and allow air into the line breaking the suction. I will try this if all else fails.

The valve is *far* above the highest sprinkler, about 60 feet.

I know the valve is fully closed, i.e. turn so it is not manually on. There is no leakage at the valve therefore I don't think the bleeder valve is open but will check. I have 15 other valves in the system and none exhibit this behavior but also none of them are in this uniques situation. I will diassemble the valve and clean it/check the diaphrams and screens.

The guy at Rainbird was emphatic that I had made a grave mistake and implied I should have hired a contractor to do the work and was really stupid for not having done so. It was really a quite amazing conversation.

Thanks again for the suggestions.

Mystery solved. I finally got a chance to disassemble the valve and there was a small rock on the ledge where the diaphram seals. It was just large enough to keep the valve open once it was opened by the solenoid but when I closed the downstream mechanical valve the flow was stopped and the diaphram would reseal. Any larger and the valve would never seal and any smaller it would have gone unnoticed. Obviously Rainbird gave me bad info because the valve works just fine now. Thanks again for the suggestions.