BoilerFaultCodesWhat the manual says
Manufacturer manualTemperature 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.
Avoid the next call-out bill
A cover plan would handle faults like E30: no call-out fees, no surprise bills.
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