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.

Kunk35

New Member

Posts: 7

Location: North Texas

1

Saturday, April 23rd 2011, 2:24pm

Backflow preventor and antisiphon valves

Is a backflow preventor the same thing as an antisiphon valve?

Kunk35

New Member

Posts: 7

Location: North Texas

2

Saturday, April 23rd 2011, 3:06pm

5 years ago when we moved here, the sprinkler system wasn't working. The guy that inspected the house told me he thought the backflow device wasn't working and to replace with a new anti-siphon valve. Not knowing what I was doing, I bought one at Lowes. The problem is, the new ones have solenoids where my old brass one did not. I managed to get it working without hooking up the solenoid, but I'm pretty sure it isn't working like it is supposed to. Aside from that, I'm not 100% sure I am protected from back flow. After reading up on how sprinkler systems are supposed to work, I realize now how important that little detail is to work properly. So, I'm trying to determine what I need to put on my system. I don't really understand yet the differences of the different types of back flow preventors. I really wish I would have saved my old one and repaired it, or got the exact replacement. That's what I get for getting in a hurry and thinking, "ahhh, it will work". The device is connected to Pvc piping about 2 feet above ground. So, what suggestions are there for my situation?

wsommariva

Supreme Member

Posts: 332

Location: Northern New Jersey

3

Saturday, April 23rd 2011, 4:34pm

Two very different things. Go to sprinklerwarehouse.com and look at the backflow devices. Sounds like your old one might have been a Pressure Vacume Breaker - PVB.

Maybe call in a pro to help you with it and show you how things work. Or if it was indeed a PVB, buy one and put it in.

Wet_Boots

Supreme Member

Posts: 3,884

Location: Metro NYC

4

Saturday, April 23rd 2011, 6:41pm

It is a Pressure Vacuum Breaker that is supposed to be in a location where the backflow preventer is higher than the highest head. Very likely the original part was a chump-change imitation that can't function under continuous pressure.

Kunk35

New Member

Posts: 7

Location: North Texas

5

Saturday, April 23rd 2011, 6:59pm

Okay, I found a Febco #765 and got it installed. Wish I would have done this 5 years ago. That dude was expensive! Thanks for the posts. There is more to these sprinkler systems than I thought.

I have some digging to do on one of my zones though. There is a major pipe break that is cutting the pressure so much the heads won't pop up. That zone will be turned off for a while until I can get it located.

Wet_Boots

Supreme Member

Posts: 3,884

Location: Metro NYC

6

Sunday, April 24th 2011, 10:25am

Read the instruction sheet that comes with the 765 ~ you need to know it will suffer damage if the water in it should freeze

Kunk35

New Member

Posts: 7

Location: North Texas

7

Sunday, April 24th 2011, 9:41pm

Good point Wetboots. I guess that is why it comes with 2 shutoff valves. I won't have to worry about it for a while, but I'll keep that in mind next winter.

Wet_Boots

Supreme Member

Posts: 3,884

Location: Metro NYC

8

Monday, April 25th 2011, 9:13am

Shutoff valves won't keep it from freezing. You need to drain it, and the shutoff valves, or it can break from freezing.

joshknight

Unregistered

9

Tuesday, May 3rd 2011, 10:20pm

backflow constantly purging water

My backflow valve seems to be constantly trickling water out of it as long as a water supply is on. This use to happen only after the sprinklers would shut off but now it is doing it non stop. Is this easily fixed by getting a new one or is it something more involved, IE getting a new electronics panel or...?

WaterSpecialtiesCo

Starting Member

Posts: 1

Location: New Hampshire

10

Wednesday, May 4th 2011, 7:32am

RE: backflow constantly purging water

My backflow valve seems to be constantly trickling water out of it as long as a water supply is on. This use to happen only after the sprinklers would shut off but now it is doing it non stop. Is this easily fixed by getting a new one or is it something more involved, IE getting a new electronics panel or...?



It all depends on which type of device you have, to me it sounds like a Reduced Pressure Zone Assembly (RPZ) or a Pressure Vacuum Breaker (PVB). Either way, this has nothing to do with electronics. If its an RPZ, which I'm assuming it is, there is probably some dirt/debris stuck in the first check. An RPZ will have a first check, a second check, and a relief valve port. Does it continue to drip when the system is running water? If if doesnt drip while running, it is most likely a first check problem. Both the RPZ and PVB can be repaired or you can replace the whole valve as well. A few things you will want to do is get the brand, model number, and size off of the I.D. tag on the backflow device.



The reason it used to drip when the sprinklers shut down is when they close it is a quick solenoid valve slamming shut causing a shock wave to travel up the system and the backflow will dump off the extra pressure to equalize the system pressure. A lot of times you can solve this problem with a hammer arrestor or expansion tank. after the backflow preventer. I hope this helps you out, any more questions, please feel free to ask.



-Josh

backflowpreventer.com
Water Specialties Company

Backflowpreventer.com

Rate this thread