Sprinkler System Backflow From Elevation Change

[Nessism]

I just finished installing a two-zone sprinkler system in my backyard. One zone has a small area that's at a higher elevation than the control valves, and when the solenoid valve on that zone closes, water backflows and splooges out the anti-siphon portion of that valve.

I'm thinking about installing a secondary Pressure Vacuum Breaker valve in the system, to further protect the potable water supply, but that won't stop the water from backflowing out of the control valve every time the system is used. I wouldn't mind the water dumping when shutting off, but I'd like that to happen off the patio. Maybe add an additional vacuum breaker, just off the patio? Open to suggestions...

 

[manwithtools]

Check valve in the pipe nearer to the spray heads?

 

[Shiftless]

The instructions for anti siphon valves say to install at least 6 inches ABOVE the highest sprinkler head.
So to prevent water from back flowing onto your patio, you an either raise the anti siphon valve or install an electric valve and a dual check valve assembly to replace your anti syphon valve.

They are complicated and expensive. That’s why I raised my anti siphon valves 2 feet above the level of my patio.

 

[Nessism]

Yes, the anti-siphon valves needs to be higher. Adding a check valve is not the ideal fix. Guess I need to redo the plumbing. I'm going to order a proper Pressure Vacuum Breaker valve, elevate that 12" above the highest sprinkler head, and then use simple solenoid valves to control the sprinkler system. Removing the solenoid valves with integrated vacuum breakers. Kind of frustrating, but the plumbing will be simple enough. The valves can go under my box, but the PVB will stick up a couple of feet.

 

[Shiftless]

Kind of frustrating, but the plumbing will be simple enough. The valves can go under my box, but the PVB will stick up a couple of feet.

Your wooden box looks nice. Just build a skinnier one to cover the piping and the vacuum breaker. If you don’t build a box or at least paint the pipe, the PVC pipe will be exposed to sunlight UV that will badly degrade the plastic and make it quite brittle.

 

[larry4406]

Not sure if this is relevant, but at the day job, we have pumped septic systems called “drip irrigation”.

They are small diameter tubes (3/4-1”) that are perforated and shallow buried in an array.

The systems pump up hill to the field, turn downhill to meet the distribution box, then down hill thru the lines.

There is a vacuum breaker at the top of the hill. It closes automatically while pumping. After the pumping quits, pressure decays and the lines drain and the effluent prior to vacuum breaker drains back to the pump chamber.

 

[Wrench97]

Yes, the anti-siphon valves needs to be higher. Adding a check valve is not the ideal fix. Guess I need to redo the plumbing. I'm going to order a proper Pressure Vacuum Breaker valve, elevate that 12" above the highest sprinkler head, and then use simple solenoid valves to control the sprinkler system. Removing the solenoid valves with integrated vacuum breakers. Kind of frustrating, but the plumbing will be simple enough. The valves can go under my box, but the PVB will stick up a couple of feet.

Can you elaborate on why a check valve is not a ideal fix?