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Loco1000

New Member

1

Thursday, August 5th 2021, 8:34pm

Sprinkler Valve Whines When Flow Control Tightened

I have six zones all with Green Lawn 71-CFC valves. The valves are old but still work so I have only changed the sprinkler heads from Mini-Paws to Rain Bird 42SA. If I had taken into account that I have 80PSI coming from the house I probably would've gone with 32SA's on the two zones in the front yard, but since I've already spent the money and did the work to install them I'm trying to find a way to reduce the throw. One zone is watering the street and the other hits the house. I have tightened the adjustment screw down pretty far, but I think the best solution is to reduce the pressure to those specific zones.

The valves have flow control, but when I tighten it down on the zones the valve starts making an awful whining noise until I loosen the valve back open. I tried switching the tops of the valves and the diaphragms with some of the others but it didn't solve the issue. Does anyone know what is causing the noise and if there is a way to fix?

Wet_Boots

Supreme Member

Posts: 5,376

Location: Metro NYC

2

Saturday, August 7th 2021, 12:21am

Leave the valves be, and focus on the sprinkler heads

The Rain Bird 5000 series rotor comes with a nozzle tree with a dozen sizes, including low-angle nozzles that don't throw as far. Its consumer version is the 42SA, and it should have the same nozzle tree. Besides the low-angle nozzles, there are extra-large nozzle sizes that might reduce zone pressures all by themselves, because increased flow means more pressure loss in the zone, even with the zone valves wide open.

Loco1000

New Member

3

Monday, August 16th 2021, 8:09pm

That didnt seem to work

Thanks for the advice Wet Boots! I swear I posted a reply a week ago, but it didn't seem to save.
I have the nozzle trees and the logic makes sense so I tried putting bigger nozzles on the heads, but that did not reduce the pressure. Interestingly, the Rain Bird nozzle guide shows the bigger nozzles shoot farther, not less. Not sure how the physics make that possible but that is what happened.
I'm still very curious why the valve whines when I tighten the flow control. The only posts I have found with a similar problem all relate to drip lines, but I haven't found anything related to regular sprinklers.

mrfixit

Moderator

Posts: 2,567

Location: USA

4

Tuesday, August 17th 2021, 5:30am

All valves will complain if you turn the flow control down too far. To adjust it correctly, turn the flow control down until you can hear it then back it off a bit.

The flow control isn't designed to adjust the pressure. It controls how much water gets past the valve. "flow control"

The valves are old. Maybe look into installing a new diaphragm.

Wet_Boots

Supreme Member

Posts: 5,376

Location: Metro NYC

5

Friday, August 20th 2021, 2:05pm

The largest nozzles on the 5000 series use 8 gpm, so three of them operating at 40-50 psi means the zone is using 24 gpm. Yes, larger nozzles will spray further, if choosing them does not bring down the pressure. Try the low-angle nozzles. They may get you the distance reduction you want, without too much radius adjustment needed.

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