The boiler displays 'Blocked Intake', 'Air Block', or similar; it may fail to ignite or run erratically.

Safety first: Turn off power before modifying intake piping.

• 1. Inspect intake termination: Outside, check the combustion air intake hood or pipe. Remove snow, leaves, or debris. Ensure any screen is clean and not overly restrictive.
• 2. Check intake piping: Inspect for crushed, disconnected, or sagging sections. Repair or replace as needed.
• 3. Room air issues (if direct-vent/room air mix): Ensure the boiler room has adequate combustion air openings and is not under strong negative pressure from exhaust fans.
• 4. Reset boiler: After clearing the intake, restore power and reset the control. Observe ignition and flame stability.