Fixing a Zone That Won’t Shut Off After 5 Minutes

The Likely Culprit: Flow Control Set Too Low

If zone 1 runs fine for the first 5 minutes but then refuses to close, the valve’s flow control (the large knob on top) is probably throttled down too far. This creates insufficient pressure differential across the diaphragm to force it shut when the solenoid de-energizes.

Proper Flow Control Adjustment

1. Turn the flow control knob fully counter-clockwise (wide open).
2. Turn it fully clockwise (closed) while counting the number of turns.
3. Reopen it to roughly half the total turns (or slightly more).

The small knob with a slot is the manual bleed screw—leave it snug (finger-tight) during normal operation.

If Adjustment Doesn’t Work

• Disassemble the valve and clean the diaphragm, seat, and all ports.
• Replace the diaphragm if it’s torn, warped, or permanently deformed.
• Check for a cracked valve body—replace the entire valve if found.

Why It Worked Before

Mineral buildup, a small stone, or diaphragm fatigue can gradually reduce the valve’s ability to close at a restricted flow setting. The 5-minute delay corresponds to the time needed for downstream pressure to bleed down enough that the weakened spring can no longer seal the valve.