Zone 1 Valve Sticks Open Annually

Recurring Valve Failure on Zone 1

Second year in a row: Zone 1 valve stays open. When Zone 2 starts, Zone 1 pressure drops briefly then Zone 1 re-engages. Valve replaced last year; worked all season. Flushing, solenoid replacement didn't help.

Diagnostic Steps

1. Flow control adjustment: Open fully, close fully counting turns, reopen to halfway.
2. Wiring test: Move Zone 1 wire to an unused controller terminal. If problem follows wire, it's a controller/output issue.
3. Check connections: At controller and valve; look for nicked insulation on common wire.

Likely Causes

• Controller output stuck on (failed triac).
• Wire short to common or another zone.
• Valve diaphragm debris (but new valve makes this less likely).

If wiring swap fixes it, replace controller. If not, investigate valve or field wiring.