BoilerFaultCodesYour boiler has sensed that water is not circulating quickly enough through the system, so it has safely shut down to prevent overheating.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Low flow condition - boiler will shut off and not lockout
What causes this fault?
This fault occurs when the temperature difference between the water leaving the boiler and returning to it becomes too wide, indicating that heat isn't being carried away fast enough. The most common reasons are a failing internal pump that can't push the water through, or a blockage caused by a buildup of sludge and debris in the system. When the water moves too slowly, it lingers in the heat exchanger and risks boiling, triggering a safety shutdown.
This fault is frequently noticed at the start of autumn when the heating is first turned on after summer, as pump components can seize during long periods of inactivity.
DIY fix possible
Check that all radiator valves are fully openEnsure the central heating pump is running and hasn't seizedCheck that the system pressure gauge is between 1 and 1.5 barBleed all radiators to remove trapped air
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like F/R ∆T = 45°C — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Remeha Quinta 30 is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.