S.85 Low
Your boiler is struggling to move enough water through its system, which is slowing down its performance.
Technical description: Service message quantity of circulation water
Typical repair cost: £90-180 (including labour)
DIY fix possible
Check that at least two or three radiator valves are fully open to allow water flow.Ensure your system pressure is topped up to between 1.0 and 1.5 bar.Bleed your radiators to remove any trapped air that might be blocking circulation.
Protect yourself from future repair bills
A boiler cover plan would cover faults like S.85 — no call-out fees, no surprises.
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Parts commonly replaced
- Central heating pump
- External bypass valve
- Filter (needs cleaning)
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