Backflow install question

fogyreef · Feb 8, 2017

In Tampa, FL I've decided to install an inline "fertigation" unit to my irrigation system, so now I'm learning about backflow preventers.

I believe the first picture is an example of an Atmospheric Vacuum Breaker (anti-siphon), which I read is not recommended, so I picked up a brass Pressure Vacuum Breaker at Lowes today. I was reading up on those when I came across the second picture showing the installation height of 12" above the highest outlet.

I have several sprinklers on 3 foot extensions with a popup (as came with the house). Do I seriously have to make a 4 foot high install? The first picture is the current install as is, basically on grade.

johnjh2o · Feb 9, 2017

Atmospheric Vacuum Breaker do have to be 12' above your highest head. But you can also use a double check device that can be installed 12" above ground level.

gargalaxy · Feb 9, 2017

3' extensions raiser plus a pop up sprays= 4' tall (or more) so your AVB or PVB shall be at 5' (12" above highest outlet). I would use a DC or an RPz (install 12" to 36" above ground).

johnjh2o · Feb 9, 2017

gargalaxy said:
3' extensions raiser plus a pop up sprays= 4' tall (or more) so your AVB or PVB shall be at 5' (12" above highest outlet). I would use a DC or an RPz (install 12" to 36" above ground).

I think that's what I said.