A.O. Smith heater shows E13 and will not start; often associated with condensate issues on condensing models

Safety: Disconnect power. Be prepared for water spillage when opening condensate components.

• 1. Locate condensate system: Identify the condensate trap, drain line, and any float switch assembly near the base of the heater or in the venting.
• 2. Clear trap and line: Remove the trap and flush it with clean water to remove slime and debris. Use a wet/dry vacuum on the drain line outlet to clear blockages. Ensure the line slopes continuously downward to a drain.
• 3. Check float switch: If equipped, inspect the float switch in the condensate pan. Make sure it moves freely and is not stuck in the up (full) position. Clean or replace if necessary.
• 4. Reassemble and test: Reinstall the trap with proper seals. Restore power and run the unit, checking for leaks and proper condensate flow.

If E13 persists, have a technician verify the condensate routing and switch wiring.