You are not logged in.

Dear visitor, welcome to SPRINKLER TALK FORUM - You Got Questions, We've Got Answers. If this is your first visit here, please read the Help. It explains how this page works. You must be registered before you can use all the page's features. Please use the registration form, to register here or read more information about the registration process. If you are already registered, please login here.

1

Sunday, October 2nd 2011, 11:52pm

Low water pressure, and water backflow at the Anti-Siphon valve

Hello all,

I just moved into a house with an existing irrigation system and I am trying to work out some issues. I have a sprinkler head which does not pop up and has low pressure. In addition, after the anti-siphon valve turns off, about 5-10 secs later, water will start pumping out of the vacuum breaker of the anti-siphon valve. I have removed the sprinkler head, and ran the zone to pump any debris out, then replaced the sprinkler head. I bought a new Rain-Bird jar top anti-siphon valve and replaced the old valve. Now I still have low pressure at the sprinkler head (will not pop-up), and have water coming out of the vacuum breaker at the valve; after the valve is turned off. Any ideas? I have really been putting a lot of time into this and cannot figure out what it could be. Is it possible there is a clog somewhere down the pipe to the sprinkler head?

Thanks in advance for any help / advice ! :)

Cheers,
Greg

mrfixit

Moderator

Posts: 1,457

Location: USA

2

Monday, October 3rd 2011, 12:43am

The water coming out of the valve is normal. It's supposed to do that. That's the anti-syphon part of the valve doing it's job.

There might be a break in the line. Look for flooding possibly between the last head that works and the head that doesn't. It could be anywhere along the line though.

3

Monday, October 3rd 2011, 10:40am

I can see how there should be some water coming back out of the valve, but this is a large amount of water, it goes for maybe 1-3 mins after being shutoff, and it's around 1 Gallon of water that comes out. To be fair, I do currently have that particular sprinkler head temporarily up on a 1ft high riser (was using this to drain water up and away from the hole, so I wasn't dealing with a mud pit every time I troubleshoot). So that may account for the extra water coming back up.
As far as a break, I do still get a decent amount of water flow, just not enough to raise the sprinkler head. Could it also be possible I have a clog, maybe something I could get with a pipe snake? One last question, if I do have a break in the line like you said, what is the best way going about finding and fixing that?
Thanks so much for your help, its much appreciated.

-Greg

Wet_Boots

Supreme Member

Posts: 4,045

Location: Metro NYC

4

Monday, October 3rd 2011, 12:59pm

Close off the heads, and run the zone, which forces water out of the break.

mrfixit

Moderator

Posts: 1,457

Location: USA

5

Monday, October 3rd 2011, 2:12pm

That's a lot of drainage but it happens. Your sprinkler line must be higher up in elevation than the valve. You could install a spring loaded check valve right after the valve to eliminate the drainage.

Look at the seals of the sprinklers. Do they leak a lot when the sprinklers first come on? Do they leak when the sprinklers are on? That could be the problem as well. New sprinklers may elimate the problem if they do.

Try turning off one sprinkler at a time while it's running to see if that last sprinkler pops up.

Did you turn the water back on all the way after changing the valve?

Make sure the valve's on all the way via a flow control if there is one.

I've been known to turn off the sprinkler heads to make a break in the pipe surface more quickly.

Wet_Boots

Supreme Member

Posts: 4,045

Location: Metro NYC

6

Monday, October 3rd 2011, 2:39pm

If the only drainage is when the zone shuts off, then it might be the spring-loaded heads pushing water back to the source. No big deal.

7

Monday, October 3rd 2011, 3:23pm

That's a good idea about a spring loaded check valve, if this is an ongoing thing I will do that. I assume I could then redirect the back flow water to somewhere preferable.

No, the valve does not leak when they are running, it is only after I turn it off that water comes back up.

And yes, I believe I turned the water back on all the way, never hurts to double check though.

I have tried a few sprinkler heads, one of them was brand new.

At the moment there is only one sprinkler head on this line (one of the large rain bird maxi rotor canister types). I am guess there are more connections, they were just covered up. I have a large bed of gravel covering where I think the rest of the line is.

I like your idea to cap off the sprinkler head, and turn the water on, then wait for a complete break. I bet I could then uncap the line, and see a total loss of preassure, indicating a complete break. Then I could know for sure and start digging up the gravel and then dig up the line. Does anyone want 1-2 tons of free gravel ;)

Wet_Boots

Supreme Member

Posts: 4,045

Location: Metro NYC

8

Monday, October 3rd 2011, 5:00pm

You do not tinker with the plumbing downstream of the antisyphon valves. No check valves. No electric valves. No shutoff valves. These edicts are etched in stone. If a head is higher than your antisyphon valves, lower it, or raise the valve. If the small amount of water escaping the vacuum breaker is a problem, then you change the grade so that the water drains away from the valves.

This is all very simple stuff. No need to make matters complicated.

mrfixit

Moderator

Posts: 1,457

Location: USA

9

Monday, October 3rd 2011, 7:54pm

You're the home owner. Do what you want.

Wet_Boots

Supreme Member

Posts: 4,045

Location: Metro NYC

10

Monday, October 3rd 2011, 8:50pm

You're the home owner. Do what you want.
Of course, you might want to someday sell the house, so it makes sense to follow the plumbing codes, so that it passes inspections. The codes prohibit adding any other valves downstream of the antisyphon valves.

Rate this thread