Spring Restart: Sprinkler System Won't Pressurize After Drain

After shutting off water for a freeze warning and draining via basement valve, a homeowner can't get water to sprinkler heads—only from an overflow cap. The system appears to fill but not reach zones.

Likely Issues

• Controller not powered/active: Verify controller is ON and programmed
• Valve wiring fault: Disconnected or cut wires prevent valve opening
• Valve failure: Solenoids or diaphragms not operating
• Main supply not fully open: Check all isolation valves

Diagnostic Steps

1. Confirm controller shows active zone run
2. Manually open a valve at the valve box (bleed screw)—if water flows, supply is good
3. If manual works but controller doesn't → electrical issue (controller, wiring, solenoids)
4. Check voltage at valve solenoid when controller activates zone (should be 24VAC)

The overflow cap flow suggests water reaches the manifold but valves aren't opening. Focus on the electrical path from controller to valves.