Hello I have 3 zones on a 25 foot slope (2 zones MP rotators, 1 zone drip irrigation). When the sprinkers are working, I dont' see any leaks from the control valves, but when I turn off the zones on the slope I notice water leaking from the control valves. I have Hunter PRS40 sprinkler risers with check vavles so I don't think the problem is with the sprinkler heads. I am guessing that the main line after the controller valve leading up the slope, is draning back down to through the control valves when the system is off. I do notice air coming out of the sprinkler heads when I turn on the zones to the slope.
Can I install an additional check valve after my control valve to prevent this? Or will this reduce my pressure too much (since this is a main line feeding the zones on the slope?)
I was looking at this product:
http://www.hunterindustries.com/product/micro-irrigation/hcv-check-valve
It states its good for up to 30 feet elevation change. Or is there a better solution?