Boiler shuts down and displays 'Blocked Vent', 'Vent Block', or similar; may be accompanied by pressure switch faults.

Safety first: Shut off power and gas before working on venting. Exhaust gases are hazardous.

• 1. Inspect exterior termination: Go outside and visually inspect the exhaust vent outlet. Remove snow, ice, leaves, or other obstructions. Ensure termination clearances meet Weil-McLain specifications.
• 2. Check for condensate pooling: From the boiler to the termination, look for low spots or sags in PVC vent piping where condensate can collect. Correct support and slope so condensate drains back to the boiler trap.
• 3. Examine vent joints: Look for signs of collapse, separation, or crushed sections. Repair or replace damaged sections.
• 4. Reset and test: After clearing obstructions, restore power and reset the boiler. Monitor operation through several cycles.

If the blocked vent error persists, a professional should inspect the entire vent system for proper sizing and installation.