Condensate Drain Blocked
The condensate drain is blocked or cannot flow freely. The boiler has detected that condensate is not being removed.
Frozen condensate pipes are very common in winter. Insulating the pipe with foam lagging can prevent future freezing.
Step-by-Step Fix Guide
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Step 1
Check the condensate pipe for blockages — it is usually the white plastic pipe running to an external drain
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Step 2
In cold weather, pour warm (not boiling) water over the external pipe to thaw any ice
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Step 3
Clear any debris from the drain where the pipe terminates
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Step 4
Reset the boiler after clearing the blockage
Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.