ON FLASH FLASH High
Your boiler has detected that water is not moving through the system properly or there isn't enough water inside the unit to safely heat up.
Technical description: Circulation error or dry fire
Typical repair cost: £120-£350 (including labour)
DIY fix possible
Check that your external heating system pressure is between 1 and 1.5 barEnsure all radiator valves and isolation valves are fully openGently bleed your radiators to remove any trapped air pockets
Protect yourself from future repair bills
A boiler cover plan would cover faults like ON FLASH FLASH — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation pump
- Flow temperature sensor
- Overheat thermostat
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