Question
I have a 5 zone residential in-ground irrigation system in which one of the zones has not been properly functioning for the last 4-5 months. When the zone in question turns on, about 3-4 of the 7 rotating pop-ups come up, with very low pressure streams. When I manually pull up anywhere from 1 to 3 of the the remaining pop-ups, (that hadn't popped up ),the entire system mysteriously comes up to full pressure on all 7 pop-ups. I have checked the control valve for that zone and even went so far as to remove the diaphragm so as to bypass the valve, and still ended up with the same results.

It is perplexing to think that when I pull up the pop-ups that have not popped up on their own, somehow the pressure paradoxically increases in the system, to bring the zone up to full pressure.

This is the only zone in which I have a problem.

Any suggestions?

Bob

Answer
i have a few thoughts...

compared to the other zones does it have more heads? is it the furthest from the main source? are the heads different (use more water)? what happens if you shut a few of them off and then try turning it on? exactly what type of heads are they? have you had any changes lately in the system? does it connect to the home and may be sharing with the water for the house? is it like this at all times of the day....

those are what runs through my head. I suppose the main question would be 4-5 months ago did anything change?

also the solenoid may need to be replaced. try simply cutting the wires at the solenoid and re-splicing them with new wire nuts.

if that zone was maxed-out to begin with and there was a drop in pressure or flow for any reason in the last several months (maybe your main supply has changed from the water company slightly) that valve would be the first to show the result.

sometimes changing nozzles can help - chose nozzles with a lower flow to see what happens. this is why I was thinking that if you shut a few heads off completely you could evaluate from that standpoint.

let me know how these grab you - I'm happy to continue discussing this for as long as it takes.

Good luck!