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Monday, May 16th 2011, 3:04pm

Auto flush/drain valve installation question

I recently setup a new drip system for containers on a deck (actually 2 decks, 1st/2nd floor). I want the system to drain after each run and I've identified a good place for the drainage to go. I set everything up including a DIG auto drain valve at the end/lowest point. However, I'm not sure if I'm missing something b/c it's not functioning in the way I expected it to (I've never used one before so my expectation may be incorrect). After running the system it doesn't drain. It is located about 4ft below the tubing it drains so I can't imagine that elevation change is keeping pressure high enough on the valve that it behaves as if it is pressurized. The valve is on the end of a 45 degree PVC elbow (should it be facing toward the ground at 90 degrees or parallel in order to work?). If I lift the valve up about a foot it will suddenly begin to drain. If I leave it in that orientation and then run the system it won't drain unless I move/lift it again. Any help would be appreciated.


Supreme Member


Tuesday, May 17th 2011, 11:08am

Based on specifications for Orbits plastic auto drains, they open/close at pressures in the area of 3-5 psi. A 10' tall water column has around 4psi, and you say you are running a multi-level system. So it is quite possible that you are operating right at the cut-over point for the auto-drain.

Now I personally don't like auto drains. I instead use check valves (that can hold up to a 25' water column) to keep my pipes full (so all that water isn't wasted each cycle) and manually drain the system at the end of the year.

But if you really want to use auto-drains, it sounds like you will need to install multiple ones. Install a second one about 6' higher than the current one. The higher one will drain the water higher in the pipes. Once the higher water has drained, that will reduce the pressure on the lower drain and perhaps allow it to drain.

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