Boiler shows EC and shuts down, often during long heating cycles

Safety first: Turn off power before working on the condensate system. Condensate is mildly acidic; wear gloves and eye protection.

• Step 1 – Locate condensate trap: Find the clear or opaque plastic trap at the base of the Rheem condensing boiler. Inspect for sludge, debris, or algae growth.
• Step 2 – Clean trap: Remove the trap per the manual. Flush it with clean water until all debris is removed. Reassemble, ensuring all seals are tight.
• Step 3 – Check drain line: Follow the condensate line to its termination. Look for kinks, sags, or blockages. In cold climates, check for freezing in uninsulated sections. Clear or replace the line as needed.
• Step 4 – Inspect condensate sensor: If equipped with a float switch or level sensor, verify that it moves freely and is not stuck by sludge. Clean or replace the sensor if necessary.
• Step 5 – Prime trap and test: Before restarting, pour some clean water into the trap to ensure it is primed. Restore power and run the boiler, checking for proper condensate flow.

Warning: Do not route condensate into drains that can freeze or back up. Improper condensate disposal can damage the boiler and building.