BoilerFaultCodes Main burner will not light or lights at low rate High
Your boiler is struggling to bring the heating or hot water on because it cannot detect a strong enough flow of water through the system to signal that it is safe to fire the burner.
Call an engineer soon
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 rate pump duty not sufficient. Water Filter blockad. Low flow rate system very restrictive. Low flow rate, air in system. Water section spindle bent or dry. Diaphragm split or stretched. Thermostat not seated properly. Gas supply insufficient. Heat exchanger blocked. Pump speed too slow. Flow and return pipes crossed or plaster, cement in pipes.
Typical repair cost £150-£300 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
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