Boiler displays E04 and will not start, fan may run briefly then stop

Safety: Turn off power before removing vent or intake connections. Never operate the boiler with venting disconnected except for brief testing by a professional.

• Step 1 – Check outdoor terminations: Inspect the Triangle Tube boiler's intake and exhaust terminations outside. Remove any snow, leaves, nests, or debris blocking the openings.
• Step 2 – Inspect vent and intake piping: Inside, visually follow the PVC or polypropylene vent and intake pipes. Look for sags filled with water, crushed sections, or disconnections. Correct any obvious issues. Ensure all joints are properly glued or clamped.
• Step 3 – Condensate check: Verify the condensate trap and drain line are not clogged. A full trap can back condensate into the combustion chamber and vent, affecting the air pressure switch. Clean the trap and flush the line with warm water if needed.
• Step 4 – Air pressure switch tubing: Locate the air pressure switch on the boiler and inspect the silicone tubing to the fan housing. Make sure it is not cracked, kinked, or filled with water. Clear or replace tubing as needed.
• Step 5 – Reset and test: Restore power and call for heat. If E04 persists, the pressure switch or fan may be defective.
• Call a technician: A professional should test the air pressure switch, verify fan speed, and confirm proper combustion and venting before replacing parts.