Constantly have to adjust watering radius of all the heads in a zone

I recently installed Toro H2flo precision spray heads on one of my zones (had same issue with conventional sprays). The zone is small, 12x 30 ft, with only 3 heads. I initially adjusted the heads to the desired radii, but every time I run the zone one or more of the heads sprays short or just dribbles. I adjust them while running and they’re fine for the duration of the watering, but then they have the same problem again the next time. My guesses as to the cause:
-Pressure too high for such a small zone
-water hammer on zone opening affecting how the heads spray
-Adjustment screw in the heads closed too much (but like i said, keeps having issues even after opening it up).

What do you guys think? Thanks.

A zone that small should probably still have more than 3 heads, but you have what you have. I’m assuming if the area is rectangular, you have two 90 degree heads at opposite corners, and a 180 degree head on the opposite side? With little to no overlap, that won’t water very evenly.

I doubt very much high pressure would cause the problem. But possibly low pressure. Or, because of high pressure, you have to restrict the flow so much due to overspray, that if pressure then lowers (even to normal levels), you don’t get as much.

You may need to add the PCD (Pressure Compensating Device) to have them spray more consistently.

Are you on a well, or anything? Even city water systems can see some decent pressure swings depending on demand on the system.

Too much pressure on a spray nozzle will usually cause it to spray in such a fine mist that it floats away and never hits the ground, so it doesn’t sound like that is the problem.

Have you check the valve itself? Almost sounds like a diaphragm starting to fail on you. If you can confirm the valve model, usually they are only $15 or so, and you can just replace the top bonnet and the guts, and leave the base of the valve in place.

Thank you for the tips.

I think I’ll start with cleaning the valve diaphragm and add a pressure regulating bonnet to see if that works.

It’s 2x 180* heads midway along the zone and one 180* at the end by the fence. The whole system is a weird setup by someone who didn’t know what they were doing. Just gotta work with it.

Pressure for the whole system hasn’t been a problem (on city water). The other, bigger zones do just fine.