BoilerFaultCodesYour boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Safety switch off low water pressure
What causes this fault?
This fault occurs when the internal water pressure drops below the safe operating limit, causing the boiler to shut down to prevent damage to the heat exchanger. The most common reasons for this are a leak somewhere in the central heating pipework or radiators, or simply that the system needs to be topped up after air was bled from the radiators.
This fault is frequently seen in autumn when homeowners turn their heating back on for the first time and discover the pressure has naturally depleted over the summer months.
DIY fix possible
Locate the filling loop valves underneath your boilerSlowly open both valves to let water into the systemClose both valves tightly once the pressure gauge reaches 1.5 bar
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.22 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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