118 High
Your boiler has detected that there is not enough water in the system to operate safely, causing it to shut down temporarily.
Technical description: Water pressure too low
Typical repair cost: £0-120 (including labour)
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath your boiler.Slowly open the one or two taps/valves on the filling loop until you hear water entering the system.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps fully.
Protect yourself from future repair bills
A boiler cover plan would cover faults like 118 — no call-out fees, no surprises.
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Parts commonly replaced
- Filling loop valves
- Expansion vessel
- Pressure sensor
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