Mounting RPZA to deck joist

[XR4ti]

Hello,

I'm a over a year away from my irrigation project, however I am finishing my basement this spring so I want to get my irrigation supply line and control wiring in place before the ceiling is closed up.

The front and sides of the house are cultured stone, so I would prefer to punch out of the house in the back.

The back side of the house is much more exposed than the front. The red line at the attached photo is the top of the highest sprinkler. (Maybe even higher than that if I decide to put a couple sprays in the perennial garden). A traditional PVB would have to travel quite a bit up the wall, then back down to be distributed.

I am considering an RPZA which just has the requirement of being 12" above grade. I am wondering if I can keep it out of sight by mounting it along a joist under the deck? My bad photoshop shows the 1" copper exiting the house, into the RPZA, then down one of the posts to go below grade to be distributed. I'd have unions for removal / testing / service, and the copper secured with bell hangers or similar.

How often do those things discharge out the bottom, would I have flooding issues under the deck?

Thanks

 

[BRD]

You can do as you have stated as long as the appearance is not objectionable to you and it is mounted so that it can be tested. Be aware that the pressure loss through a RP assy (3/4-1") is approx. 12psi. You will have to factor this into your hydraulics when you design the system. A pressure vacuum breaker will loose aprox. 3 psi at 12gpm but will have to be located above the highest head. If your elevation slopes down from the front of the house you may want to exit your piping from the higher front elevation and use a PVB. If pressure is an issue you may want to do this also. I would also add a drain just after the inside shut-off valve so as to insure complete evacuation of water at winterization from the pipe leading to the backflow device. RP's will sometimes spit water intermittently but should not be of concern. Should the relief valve become stuck for some reason then you would have a continuous flow of water from the backflow device. If you are on a well I would certainly have a 100 mesh filter before the back flow device if it is a RPZ assy. Good luck