BoilerFaultCodesTechnical description
Temperature differential exceeded
What causes this fault?
This fault occurs when the internal sensors detect that water isn't flowing away from the heat exchanger quickly enough, causing a rapid heat buildup. The most common reason is a failing circulation pump or a blockage in the system caused by a buildup of sludge and debris. It can also be triggered by air trapped within the boiler or a sensor that has become faulty and is giving incorrect readings.
This fault is more common in autumn when heating systems are turned back on after a long summer break, as pumps can seize and debris often settles while the system is inactive.
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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