Originally Posted by DanaMac
leaking wiper seals at the heads. Or the zone is stretched on GPM. Or combination of all of it. Try nozzling down to start, and do the check valve heads that WB mentioned, at least on the lowest one or two heads.
Thanks for typing what I was thinking.
To the OP:
Just worked on a similar situation. 5 PGP's on this one zone that *use* to perform much better. Has a booster pump on 5/8" meter with 3/4" Cu main. Heads slow to rise, don't spray very well. Sunk below turf, dated from 1999, leaky at the seals and shafts all scratched up.
Started at the furthest head. Each head I replaced, the pressure would increase 4 psi to 7 psi. They would all spray a little better/further too. Started at just about 23 psi measured at the manifold hose bibb, pump running, before I started replacing. Pressure now at almost 50 psi. More importantly they are all pumping much more water from the nozzles.
Leaky seals - a little at each head and the whole zone suffers if the volume isn't available to make up for the loss.
Now, I've seen a zone with 7 or 8 PGP's w/#7 nozzles on a 1.5" line with over 120 psi static pressure. Leaky seals on all yet they all also pump out a lot of water and each looks like normal volume. Commercial customer doesn't care about the water waste since the heads "are all working fine". I've also seen a broken head on a zone, water shooting straight up. Yet all the other heads pumping out water like nuthins wrong.