SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Quoted from "desmo907"

When replacing my old Toro valves I noticed a very fine spray coming out of the Febco 715 Atmostpheric Vacuum Breaker.

It is a simple connection with [2] 3/4" female ends (top, side) to connect a brass pipe from home to poly that feeds a open/close valve to the manifold.

Do NOT replace an Atmospheric Vacuum Breaker (AVB) with something similar. What you have described is not legal. It will cause problems and fail again. An Atmospheric Vacuum Breaker is not legal, installed and protecting water in a pipe system that a valve closed after the AVB. An irrigation valve counts as a valve. Your device is leaking water because the seals have compressed to the point of failure.

Check with your Municipality or Water District. You should be installing a Pressure Vacuum Breaker (PVB) backflow prevention assembly, or a Double Check Valve (DCVA) backflow prevention assembly.

Mick

Mick is steering you in the correct direction.

The only place an AVB should be installed in an irrigation system is AFTER a valve... meaning each valve would need its own AVB, and such valves are sold (where the valve and AVB are already together as a unit). But then, even this type of arraingement may or may not be legal in your community.

When it comes to back-flow prevention, the rules vary from place to place, and can be as strengent as "you must use company X back flow preventer part number ###" to as laid back to "any back flow preventer installed per manufacturers directions". So your first step needs to be contacting your local building department and asking what are the local requirements regarding irrigation backflow prevention.

It is very common to see this sort of "pretend backflow protection" on older systems. as long as the old AVB is located at least a foot higher than any sprinkler head it feeds, you can swap it for a PVB

Quoted from "desmo907"

I'll get the FE765-075 - Febco® 3/4 inch PVB Assembly to replace it.
It looks easy to replace.
I am well above the 12 ".... and there doesn't seem to be any local rules (and think some of my neighbors have the same device).

It does appear the guy who installed this system years ago didn't do well.. He had too many zones, and buried the valves without a box

I understand that your municiplity/water provider doesn't have any local rules, but you should know (what you do with this information is up to you) that municipalities that do have rules, and all manufacturers of backflow prevention assemblies require the assembly be tested when installed, if the assembly is repaired, moved and at least once a year.

You also might want to get valve box(es) over your valves for protection.

Mick