Zone 5 Won't Fully Close: Pressure Loss to Zone 6

When zone 5 doesn't shut off completely, zone 6 starves for pressure and dribbles. This indicates a valve 5 mechanical issue—not a controller problem—since the controller correctly de-energizes zone 5 before energizing zone 6.

Diagnostic Flow Control Test

1. Locate valve 5 (usually in same valve box as zone 6).
2. Turn flow control knob fully clockwise (closed).
3. Manually activate zone 6 from controller.
4. If zone 6 now runs strong: Valve 5 was leaking by. Focus repair on valve 5.
5. If zone 6 still weak: Both valves 5 & 6 may have issues, or mainline pressure is low.

Valve 5 Repair Steps

1. Shut off main irrigation water.
2. Remove solenoid and bonnet.
3. Inspect diaphragm for tears, debris, or curled edges.
4. Clean valve seat and diaphragm with water only.
5. Check solenoid plunger for smooth action.
6. Reassemble; test with flow control fully open (counter-clockwise).

Other Possibilities

• Crossed wires: Zone 5 & 6 hot wires touching—rare but possible if insulation damaged.
• Controller overlap: Programmed start times too close; check for "stacked" starts.
• Flow control set too low: Previous adjustment restricting valve 5 closure.

When to Replace Valve

If diaphragm is torn, seat is pitted, or valve body cracked, replace the entire valve (or internals if same model). Anti-siphon valves must remain 12"+ above highest head.