Display shows E12, unit may lock out, often associated with condensate issues on condensing models

Safety: Condensate is mildly acidic. Wear gloves and eye protection when handling.

• 1. Locate condensate trap: On ACV condensing water heaters, the trap is usually at the base of the heat exchanger or flue collector.
• 2. Inspect for blockage: Remove the trap and check for sludge, scale, or debris. Clean thoroughly with water and a soft brush.
• 3. Flush drain line: Check the plastic condensate pipe to the drain. Flush with warm water to clear any blockage. In freezing weather, thaw any frozen sections and insulate the pipe.
• 4. Check level sensor: If the trap has a float or level sensor, ensure it moves freely and the wiring is intact.
• 5. Reassemble and test: Refit the trap, ensuring seals are correctly seated. Restore power and test operation.

If E12 persists, the condensate sensor or control board input may be faulty and should be checked by a technician.