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I am making a misting system for my back patio that consists of 1/2" pvc and connectors that have the misting nozzle drilled. I am putting a nozzle every 2 feet and going about 30 feet down my patio cover

I plan on using a sprinkler water supply hard out that is currently capped off. Next to my other sprinkler valves and running 3/4" PVC to the patio and then convert to 1/2"after I run vertically about 8ft with the 3/4" pvc. The distance from patio to valve is about 14ft horizontally.

At the end of the 1/2" run, I am just going to cap the pvc.

My question is, what kind of valve should I use since this is a long run of pvc and it has height, meaning lots of backflow/pressure. I was thinking of just using a common sprinkler anti-siphon valve, but would the entire contents of the pvc exit the valve when I turn it off? My pool top off uses a gate valve with no backflow and it has a little water hammer effect on start and stop, but works fine. The exit is below the valve though.

I was hoping to use a sprinkler valve with a solenoid so I could eventually hook it up to my sprinkler controller and digitally control the misters. Eventually I would get the IP controller and be able to do it from my phone, but I want to make sure I handle all that water above the valve correctly.

Any assistance is appreciated.

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I don't think you need to be concerned with using an anti-siphon device, as the potential for contamination is minimal (compared to water making contact with the soil).

If you want to automate then use an in-line solenoid controlled valve without anti-siphon, then you don't have to worry about the remaining water standing in the pipe length from running back out of it:

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  • Thank you, this is what I was wondering. I will get the valve without anti-siphon. Do these valves experience water hammer or any back- pressure related issues if the head pressure is higher than ground level? – Jeff Harding Aug 11 '17 at 20:49
  • I have experienced some minor hammer when they close, but with your application (which I would consider a very low flow application) I don't think it will be an issue. Backpressure is normally not an issue because the system is open-ended. They do rely on lower downstream pressure for the valve to open, which you will have initially. But I'm not sure what will happen in the event that the total pressure drop while operating is low. Hopefully the number of open misters will provide sufficient flow/pressure-drop to overcome head pressure + back pressure while operating. – Jimmy Fix-it Aug 12 '17 at 17:53
  • Pick a valve and check manufacturer's specs for max back-pressure, although it would be difficult (I think) to predict what your final operating downstream pressure will end up being. The valves are cheap, I would probably just build it and hope for the best, but give yourself a manual shut-off in the line as an alternative, and a way to bypass or remove the auto-valve if needed. Actually, if it doesn't work you could just pull the guts out of it. – Jimmy Fix-it Aug 12 '17 at 18:02
  • Can I install this valve above ground like the anti-siphon valves for my sprinklers? Meaning putting 90s on the ends and having it sit above the ground with the supply lines running back into the ground – Jeff Harding Aug 16 '17 at 19:11
  • No reason at all that you couldn't, just think of it as a solenoid operated in-line valve. The only difference is that it does not have the anti-siphon mechanism. – Jimmy Fix-it Aug 17 '17 at 1:00

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