Hello. Please help me out. This is what my RP and set up looks like. Without taking the valve assembly completely out, where would I place the pipe for the air pressure to blow out the lines/heads? The water flows from right to left in the picture. Test cocks are shown and are left to right numbers 4,3,2 and 1.
A local plumber (unfamiliar with this type valve) suggested an air nipple in test cock #4 (leftmost in picture.)
I thank you all in advance for your help. advice and consideration.