Originally Posted by johnjh2o
First off that's not a dual check. It's an RPZ device. (reduced pressure zone) That device can not be installed under ground. A dual check is not and approved device because it can't be tested. You may be thinking of a DBL check. That device has test cocks a dual check doesn't. Both the RPZ and the DBL check are much more expensive then the PVB
(pressure vacuum breaker). What is your reason to not use the approved device for your irrigation system. (PVB)
Is a RPZ and double check the same except the pressure reduction? It looks the same:http://www.amazon.com/Wilkins-Double-Check-Backflow-Preventer/dp/B0006B07A6/ref=sr_1_1?s=hi&ie=UTF8&qid=1381428926&sr=1-1&keywords=Wilkins+double+check+valve
I'm 100% sure the double check and RPZ devices are approved where I live because I literally see them everywhere on commercial properties. I have never seen that PVB devices anywhere in CA so I don't think that's legal here.
The reason I'm looking to get a separate check valve is so I don't have to use those above ground anti-siphon valves, but instead use a bunch of buried inline valves. Even if I have to elevate the double check, it would only be one thing elevated while I can bury the many inline valves I need.