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andrew

New Member

1

Thursday, July 5th 2018, 11:04pm

entire zone with new heads that won't pop up without help

I have an 8 zone system. 7 zones are fine. One zone seemed to have low pressure. On this zone I have 5 Hunter PGP rotors plus two fixed pop-up nozzle sprayers. (Yes I know they are not supposed to be mixed but that's how the guy set it up 20 yrs ago, and it worked fine for a long time)

A bunch of the heads were leaking, so I replaced them all with new ones, same type, but replacing red #4 nozzles with blue 2.0 gpm nozzles. I tested the zone as I replaced each head. With each of the first three replacements the pressure seemed to improve. I checked for leaks before filling each hole. Finished day 1 satisfied that I was on the right track.

Then today I replaced the last two, including one that was so buried that it wasn't popping up at all and was hard to even find. Now none of them will pop up on their own. Yesterday, with 3 new, 1 working old one, and one stuck-in-ground old one, worked ok. Today, all 5 are new, whole zone doesn't work, just weak burbling from all 5 rotors, nothing from the sprayers.

However, if I "help" one of the rotors - any one - by pulling it up and holding it there for a few seconds, then the others will get going. once they are all up, they work beautifully, seemingly with nice pressure. On close up inspection, when they are running properly after getting help getting started, none of them appear to have any leaks. There's no indication I can find of a leak anywhere else.

I THINK what is going on is that the new heads are allowing more blow-by at start-up than the old ones (?), so not enough pressure is building up to raise them. I guess that when I pull one of them up, I am reducing the blow-by just enough to boost the pressure enough for everyone to get up? and then once they are all up, they stay up because there's no more blow-by. Maybe the new blue 2 gpm nozzles also are passing more water than the red #4's. My whole house's water pressure is on the low side.

My tentative solution is to remove and cap one of the rotors that I don't really need anyway. (It would be the rotor that is closest to the valve manifold, if that's relevant). On my other zones, I have, at most, 6 rotors, here I have 5 plus the two fixed sprayers. So maybe eliminating one will boost the pressure enough to get it working. That might explain why it was working ok after replacing only 3 rotors - that one that was stuck in the ground was basically like a capped one.

Another option could be to replace the 2.0 nozzles with 1.5. These heads only cover 180 degrees so I could live with that easily.

Any other ideas or recommendations or troubleshooting advice would be most welcome. Could I have a problem at the valve that, if fixed, would make the whole zone work fine as is? This is a zone that, over the years, I have tended not to use much but I am hoping to get it working properly now that I have planted a lot of new stuff there.

This post has been edited 2 times, last edit by "andrew" (Jul 5th 2018, 11:17pm)


mrfixit

Moderator

Posts: 2,307

Location: USA

2

Thursday, July 5th 2018, 11:41pm

Are you sure the valve's working properly? Try opening it with the bleeder screw.

You might be operating right on the edge of the available water supply.

Here's the charts.





The red #4 at 45lbs is 1.5 gallons per minute. The one you uninstalled.
The blue 2 is 2 gallons per minute. The one you've installed. So you've increased the amount of water used by 25%.
Maybe you're over the limit.

andrew

New Member

3

Friday, July 6th 2018, 12:36am

I am not sure about the valve. I'm going to try checking it tomorrow. Haven't messed with valves before so I am not 100% sure how to use the bleeder screw but I will try to figure it out, just to be sure.

Thanks for the reply. I am more and more thinking I just need to swap out the nozzles. Just typing out the details of my situation here helped me realize that!

andrew

New Member

4

Saturday, July 7th 2018, 6:32pm

I replaced all the nozzles with 1.5 GPM. No improvement.
I ran the zone by twisting the solenoid, and the pressure is still low.
Does that tell me I should replace the guts of the valve?

mrfixit

Moderator

Posts: 2,307

Location: USA

5

Saturday, July 7th 2018, 6:36pm

Turning the solenoid isn't the same as opening the bleeder screw.
At this time I'd say there's either a leak somewhere or the valve isn't coming on all the way.
What model valve is it?

andrew

New Member

6

Saturday, July 7th 2018, 9:48pm

It’s a hunter PGV. No flow control. It’s about 20 years old. I didn’t realize it mattered which way I activated it manually. I had to dig the dirt from around the valve so I just used the solenoid because it was easier. I will try the bleeder approachh tomorrow. Can you tell me what it means if the bleeder does or does not change the behavior. Like if the bleeder delivers full pressure does that mean the valve is or isn’t ok?

mrfixit

Moderator

Posts: 2,307

Location: USA

7

Saturday, July 7th 2018, 10:45pm

I'm not a big fan of valves without flow controls. If I was you I'd buy a Hunter PGV and swap out all the parts.

If the valve comes on full force when you open the bleeder screw then you know there's something wrong with the valve. This isn't a tell all, it's just a test. Even if the valve shows no difference doesn't mean there's nothing wrong with the valve.

If you have a hose bib near by you can attach a pressure tester to it. Turn on the other valves one at a time. Note the pressure loss. Then try the problem zone. Does the pressure drop like the others? It might even drop more if there's a broken pipe.

andrew

New Member

8

Sunday, July 8th 2018, 11:51am

I seem to have a PGV that does not have a bleeder screw(?)



[img]https://drive.google.com/open?id=10QhKV9HduVRTgjsPhKIlHUI4N2wJhWrq[/img]
[img]https://drive.google.com/open?id=1j4FNuYuoDpcGiN_J1G7Du20TGLHIWwdP[/img]

This post has been edited 2 times, last edit by "andrew" (Jul 8th 2018, 11:58am)


mrfixit

Moderator

Posts: 2,307

Location: USA

9

Sunday, July 8th 2018, 1:23pm

I can't make any guarantees from here. I'd buy the new PGV with flow control and swap out all the parts. That valve is extremely easy to rebuild. If it doesn't fix the problem then oh well. You've gained some experience fixing your valves and you have a rebuilt valve.

You can get one from our site. I posted the link earlier or order one from Home Depot or go to a local Irrigation supply store. They'll have it. They're cheap enough.

You could try taking the solenoid all the way off. That will release the water similar to opening the bleeder screw.

andrew

New Member

10

Sunday, July 8th 2018, 5:56pm

Yep I agree with all that. Got the valve today. Will try rebuilding. Appreciate your help.

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