BoilerFaultCodesWhat the manual says
Manufacturer manualWater circulation fault (Temperature rise too fast)
What causes this fault?
This fault occurs when the boiler detects that the internal water temperature is rising much faster than it should, triggering a safety shutdown. The most common cause is a blockage in the system or a failing pump that prevents water from moving away from the heat exchanger quickly enough. It can also be caused by air trapped in the pipework or a buildup of debris known as central heating sludge.
This fault is specifically common in autumn when homeowners turn their heating back on for the first time, as pumps can seize up after months of inactivity during the summer.
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 F24: no call-out fees, no surprise bills.
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Related fault codes
All 70 fault codes on the Ultracom 35 Store
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