104 High
Your boiler has detected that water is not circulating fast enough through the system, usually due to a lack of water pressure or a blockage.
Technical description: All Boilers
Typical repair cost: £0-250 (including labour)
DIY fix possible
Check the pressure gauge and ensure it is between 1 and 1.5 barIf pressure is low, use the filling loop to top up the water levelBleed any trapped air from your radiatorsPress the 'Reset' button on the boiler control panel
Protect yourself from future repair bills
A boiler cover plan would cover faults like 104 — no call-out fees, no surprises.
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Parts commonly replaced
- Circulation Pump
- Primary Heat Exchanger
- Central Heating Filter
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