Boiler casing or nearby walls show signs of soot deposits or black staining.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety first: Sooting indicates dangerous combustion conditions and potential CO production. Turn off the boiler and gas supply immediately. Do not attempt to operate the boiler until serviced.
Step-by-step checks (visual only):
- 1. Inspect burner area: With power and gas off, remove the burner cover and look for heavy soot deposits.
Professional actions: A heating engineer must clean the burner and heat exchanger, check and adjust gas pressures, and verify flue performance with appropriate instruments.
Repair Difficulty
Required Part
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