BoilerFaultCodesTechnical description
Flow temperature overheat lockout or no water flow lockout
What causes this fault?
This fault occurs when the water inside the boiler exceeds a safe temperature limit or isn't circulating correctly. The most common reasons are a failed pump that can't move the water, a blockage caused by sludge in the system, or a faulty sensor giving an incorrect temperature reading.
This issue is more frequent during the first cold snap of autumn when heating systems are turned on after being dormant all summer, which can cause internal pumps to seize.
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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