BoilerFaultCodesYour boiler has detected that the water inside the main heating unit has frozen due to extremely cold temperatures, preventing it from operating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Main heat exchanger frozen
What causes this fault?
This fault occurs when the temperature sensors inside the boiler detect that the water within the heat exchanger has dropped low enough to freeze. The most common reason is that the boiler is located in an unheated area, such as a garage or loft, without adequate insulation or frost protection during a severe cold snap.
This fault is exclusively seen during the winter months when external temperatures drop below freezing for extended periods.
DIY fix possible
Check if any external condensate pipes are frozen and thaw them with warm (not boiling) water.Increase the room thermostat setting to encourage movement in the system.Ensure the boiler is located in a draft-free area and keep the heating on a low constant setting during cold snaps.Reset the boiler once the unit has thawed out.
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