Boiler locks out with E15: condensate system fault detected.

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

• Step 1 – Locate condensate trap: On Triangle Tube condensing boilers, the trap is usually a clear or opaque plastic assembly located at the bottom of the heat exchanger outlet.
• Step 2 – Inspect and clean: Place a container under the trap, disconnect it, and empty its contents. Rinse with warm water to remove any sludge or debris. Ensure internal baffles are clear.
• Step 3 – Check drain line: Follow the condensate hose to its termination point. Look for sags, kinks, or freezing (in cold climates). Clear any blockage and ensure the line slopes continuously downward.
• Step 4 – Reassemble and prime: Reinstall the trap, making sure all seals are tight. Pour a small amount of clean water into the trap to prime it.
• Step 5 – Reset boiler: Restore power and reset the boiler. If E15 returns, a condensate level sensor or control fault may exist.
• Call a technician: For persistent issues, a professional should verify proper condensate routing and replace any faulty sensors.