Very helpful video, Alfred. I am designing my new system now and this question was not adequately answered in the book I have. Thanks for the detailed explanation!
Hi, I have rainbird anti-siphon in both front and backyard. I recently got them replaced from the inline valves. Now, I notice that when the sprinkler truns off, there is spurt of water from the anti-siphon emitter cap region. My contractor said its OK and there is no issue with that. Please confirm if this is fine and OK to get some water coming out after the sprinkler shuts down. Also, I am getting some water hammer when the turn off happens, water hammer was more prominent in the in-line valves.
I have the main waterline on the bottom of the hill which shoots up the hill, and the anti siphons at the top. Is that the correct setup? Or does something need to be placed inline at the bottom of the hill? In other words when the anti siphon at the top is off do I need to worry about the pressure in the line going down the hill or does it just remain pressurized and no need to worry about back flow
Depends on where you place the valves. You can do them in the typical spot where you would put anti siphon valves and you'd run about the same amount of wire. They both have their pros and cons but I decided to go with anti siphon valves. No need for a back flow preventer when you have these.
My sprinkler system is completely separate from the town water and runs off a well/pump. Is there any reason to have the anti-siphon valves in that kind of a system? Aside from the additional few bucks for the PVC when building the manifold, any reason to go with one vs. another? Thanks!
If I am running 30' PVC to feed a 4 zone system from my GARDEN HOSE SPICKET, and I use a cheaper hose bib anti-backflow preventer, do I need to bother with an (master) Anti-Siphon valve? OK to just use in line to control my zones?
You can manifold inline valves or antisphin valves... anti siphon valves are good for one thing and one thing only.... when you cant tap into the water supply at the meter and bring a mainline to the area you are working in. You may have to tap off a hose bib line under the house bypassing an existing backflow device. That's when you need a valve and backflow device in one such as the anti siphon valve... do remember though to check with your local regulations as this valve does not protect against back pressure.
Well, one can OBVIOUSLY install a backflow preventer WITH an above ground sprinkler manifold system, CORRECT ? Problem solved. My only question remains: Can I install inline type valves (ABOVE GROUND) in a manifold type configuration with obviously a backflow type device ? I would create a Unistrut type structure to mount them on... I live in year round warm / non freezing weather.
you can install them above ground. People probably just go underground because you connect to the line thats underground, also its protected from the sun/weathering and hidden away.
Doesn't an inline valve stop siphoning when it closes? Thats whats confusing me. It opens to let water through and then closes so no more water can come through, therefore eliminating a siphoning affect. Correct or no?
Yes, and no. An inline valve can fail in the open position, leading to backflow. The anti-siphon will prevent backflow, even if the valve fails in the open position.
@@SteveTomkins so of I'm using anti siphon valves, would you recommend installing a back flow preventer as well? Or is that over kill and not necessary?
@@mustanggt5985 An anti-siphon valve, properly installed, is technically a backflow prevention device. Some municipalities require a more robust backflow preventer, many do not. I'm not a plumber or irrigation specialist, so I can't really define overkill. I know that both of my homes in CA had anti-siphon valves and no other backflow prevention.
@@mustanggt5985 Some models spec 6", while others specify 12". I believe the concern is that the backpressure could overwhelm the the anti-siphon function of the valve.
