Main
Condensate Management / Flue Drainage Issue
Boiler runs but flue terminal drips heavily or stains the wall
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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.
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Possible Causes
Incorrect flue slope, Missing or blocked condensate drain from flue, Damaged flue seals, Excessive condensate due to low return temperatures
How to Fix / Troubleshooting
Safety: Condensate is mildly acidic; avoid prolonged skin contact. Flue work must comply with regulations.
- Observe flue: Some visible plume and light dripping in cold weather can be normal. Heavy dripping or staining is not.
- Check condensate pipe: Ensure the condensate pipe from the Main boiler is connected, not leaking, and discharging to a suitable drain.
- Engineer actions:
- Verify flue is installed with correct fall back to the boiler.
- Inspect flue joints and seals for damage and replace as needed.
- Check condensate trap and internal flue drain for blockage.
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Repair Difficulty
Hard
4/5
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