Boiler shows F.18, often associated with condensate issues

Safety first: Turn off power. Condensate is mildly acidic; wear gloves and eye protection.

• Inspect condensate trap: Locate the clear or opaque trap at the base of the boiler. Remove and check for sludge, debris, or scale. Rinse thoroughly with clean water.
• Check drain line: Follow the condensate tubing to the drain. Ensure it is not kinked, frozen, or pitched uphill. Correct slope so condensate flows freely.
• Clean neutralizer (if installed): If a condensate neutralizer cartridge is present, check for saturation or blockage. Replace media if necessary.
• Prime trap: Refill the trap with clean water before restarting to maintain the flue gas seal.
• Reset boiler: Restore power and reset. Monitor for leaks and proper drainage.

Professional help: If condensate continues to back up or F.18 persists, have a technician inspect the internal condensate passages of the heat exchanger.