Boiler displays E10 and shuts down; may be associated with condensate in the venting

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

• Inspect condensate trap: Locate the plastic condensate trap at the bottom of the heat exchanger or flue collector. Remove and flush it with clean water to remove debris and sludge.
• Check drain line: Ensure the condensate hose slopes continuously downward to the drain and is not kinked or frozen. Clear any blockage with a flexible brush or by flushing.
• Verify float switch: If your Ruud boiler has a condensate overflow float switch, check that it moves freely and is not stuck in the raised (fault) position.
• Reassemble and test: Reinstall the trap, ensuring all seals are tight to prevent flue gas leakage. Restore power and call for heat. If E10 returns, the float switch or control input may be faulty.