A15
Wolf Condensate Drain Blocked / Backflow Detected

Boiler shows A15, burner stops, condensate may be visible around boiler

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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

Blocked condensate trap, Frozen external condensate pipe, Incorrect condensate pipe fall, Debris in condensate siphon

How to Fix / Troubleshooting

Safety: Condensate is mildly acidic. Wear gloves and eye protection when handling.

  • Check external condensate pipe: Look for kinks, blockages, or freezing (in cold weather). Thaw gently with warm water if frozen and insulate the pipe.
  • Inspect trap (competent person): With power off, remove the condensate trap as per Wolf instructions, empty and rinse it, then refit ensuring seals are correct.
  • Reset the boiler: After clearing the drain, reset and observe operation.
  • If A15 persists: Have a technician check the internal routing and fall of the condensate pipe and the boiler’s condensate sensor if fitted.
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Repair Difficulty

Medium 3/5

Required Part

Condensate Trap
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