I am having the exact same problem with an AVB valve. All the air comes back through the AVB? I have a small air compressor but it has worked in all the past houses I have lived in. Do you need more pressure than I can supply?
So on my system I am trying to blow out the sprinklers with an air compressor. I have always done it before and it is just 2 zones so I don;t want to pay someone $40. So there is the mainline with an Isolation Ball Valve Inlet inside the house then another Isolation Ball Valve Inlet outside. Then there is a Test Cock then the AVB then another test cock on the other side of the AVB then another ball valve. I hooked the compressor to the test cock downstream of the AVB and closed the ball valve cl...
