BoilerFaultCodesTechnical description
Automatic Air Vent
What causes this fault?
This fault occurs when air becomes trapped within the boiler's internal reservoir or the pump itself, creating an air lock that stops water flow. The most common reason is a failure of the automatic air vent to release gases, or a build-up of sludge that has blocked the internal de-aerator assembly.
This issue often surfaces in autumn when the heating is turned back on after summer, causing dormant air bubbles or settled debris to move into the pump system.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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