Occupants experience headaches or nausea when the furnace is running; possible flue gas smell.
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
Critical safety warning: Turn off the furnace and gas supply immediately. Open windows and doors to ventilate. Do not use the furnace again until it has been inspected by a qualified gas engineer. Install or check carbon monoxide alarms.
User action only: Evacuate if symptoms are severe and call emergency services or gas emergency number. Do not attempt any internal repairs.
Technician checks:
- Perform flue integrity and spillage tests.
- Inspect the heat exchanger for cracks or corrosion.
- Check flue routing and terminal for blockages.
- Verify adequate combustion air supply.
Repair Difficulty
Required Part
We may earn a commission from links on this page.