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Sprinkler Valve Won't Shut Off: Flow Control Adjustment

Fixing a Valve That Stays Open

One of six anti-siphon valves fails to close at its scheduled time, running through subsequent zones and wasting water. Timer programming is verified correct.

Simple Adjustment Procedure

The valve's flow control knob (on top of the valve body) is likely misadjusted. Follow this standard procedure:

Turn flow control fully open (counterclockwise)
Turn fully closed (clockwise), counting the number of turns
Reopen to exactly half the counted turns

Why This Works

Proper flow control setting creates the correct pressure differential across the diaphragm for reliable opening and closing. Over-open valves may not generate enough closing force; over-closed valves restrict flow excessively.

If adjustment fails, disassemble the valve to inspect the diaphragm for tears, debris, or mineral buildup. Replace damaged components.

Irrigation: Sprinkler Station Won’t Shut Off – How to Turn Off Water Supply; Sprinklers Won't Shut Off? Valve Stuck Open — Not Controller; Fixing a Sprinkler Valve That Won't Shut Off: Diaphragm Replacement; Spring Restart: Sprinkler System Won't Pressurize After Drain; Leaking Sprinkler Heads: Valve Diaphragm or Low-Head Drainage?; Sprinkler System Won't Shut Off: Valve or Controller Fault?; Sprinkler Head Won't Shut Off – Valve Repair Guide; Choosing a Sprinkler Valve for Low-Pressure Tank Drainage; How to Turn On Sprinkler System Valves: A Step-by-Step Guide; Automatic Valve Won't Turn On: Zone 1 of 6 Dead

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