Hi folks, just ran across this forum and hopefully someone can help me out. I have a 4 zone auto sprinkler system at my house. I recently replumbed one of the valves to a new line for some new landscaping. This valve was for an area we no longer have landscaping in. All the valves have 3/4" piping going in and out of them. Downstream of the valve in the new line I plumbed I used a reducing 90* elbow to go from 3/4" to 1/2". This new landscaped area already had a 1/2" line plumbed under the concrete walk, etc so I didn't want to redo everything with 3/4" pipe. When I tested the new line, water started coming from the ground around the input/output lines from the valves. After some digging I found an open ended pipe buried under the valve piping. Best I could figure is that it is a pressure relief pipe if there is too much pressure in the system. Anyone ever heard of this? The other 3 valves work fine and were all plumbed before we bought the house. Here are my quetsions: Is that a pressure relief pipe? How can I reduce from 3/4" to 1/2"? Do I have to completely re-run the line? Thanks for any help!!!