Zone 1 Won't Shut Off When Zone 2 Starts—Pressure or Controller Fault

4-zone well system: Zone 1 stays on when advancing to Zone 2. Valve, diaphragm, solenoid, controller all replaced/tested multiple times. Works 5-10 cycles then recurs. Suspects well pressure/sand.

Pressure Possibility

Yes—excessive pressure can prevent valve closure. Need:

• Static/dynamic pressure per zone
• Valve models/sizes
• Pipe sizes
• Pump details

Controller Test

Measure voltage at Zone 1 terminal WHILE Zone 2 running. Should be 0VAC. If 24VAC present → controller short. Move Zone 1 wire to spare terminal if available.

Sand Theory

Unlikely only Zone 1 affected unless it's first in line from pump. But companies dismissed this.

Provide pressure/valve data for specific diagnosis.