Backflow


#1

I have a iritrol vacuum breaker valve wired as my main, supplying 6x inline iritrol zone valves. IS THERE A WAY TO HAVE RACHIO CLOSE THE MAIN A FEW SECONDS BEFORE THE ZONE VALVE? To relieve pressure

According to the main plumbing inspector for my city, using a vacuum breaker valve is acceptable for backflow protection for residential

But

According to IRITROL and Rainbird vacuum breaker valves are NOT to be used with any other valve downstream. Other than an indexing valve, which technically isnt a valve. I believe the issue is the back pressure generated by the zone valves on the main. If you closed them in sequence in theory it would be better


#2

You may be better off installing a standard PVB or Pressurized Vacuum Breaker. I have never seen a vacuum breaker made by Irritrol, let alone an electric vacuum breaker.

You may be referring to the 2700 series anti syphon valve.

If you eliminate that 1st electric valve and put a regular backflow or vacuum breaker, then your problem goes away and you can use the water hammer feature on the Rachio to slowly close the valve.


#3

Yes I was using the 2700. My city inspector says the 2700 is ok to use in that way. But the mfr says no with no technical explanation why. What’s your opinion and or what else that I expensive would you suggest instead.


#4

Most of the building codes require a minimum of a pressurized vacuum breaker. The preferred method would be a Febco 825Y backflow preventer. The PVB cost less while the 825Y has better protection for your drinking water.


#5

The reason why is this…

If you have another shut-off valve after the anti-siphon valve, then the water on the downstream side of the anti-siphon valve will stay pressurized even when the anti-siphon valve is closed. This water pressure holds the little air vent in the closed position so it can’t let in air, and therefore the siphon effect is not broken. This means the anti-siphon part of the valve will not work. Even worse, when the little vent is held closed for days at a time due to the constant downstream pressure, it eventually just sticks in the closed position. Then even if the pressure drops the anti-siphon won’t work.

You really should either replace all 6 valves with Anti-siphon models and remove the “master” valve, or install a Zurn/Wilkins or Febco backflow preventer. The Febco units are more compact than the Zurn/Wilkins if space is an issue.