S.20 Low
Your boiler has received a request to provide hot water but is currently unable to complete the cycle, often because it is already cooling down or busy with another task.
Technical description: Hot water requirement error
Typical repair cost: £60-120 (including labour)
DIY fix possible
Check if any hot water taps have been left slightly openTurn the boiler power off and back on again to reset the internal clockEnsure your external timer or thermostat is not stuck in an 'on' position
Protect yourself from future repair bills
A boiler cover plan would cover faults like S.20 — no call-out fees, no surprises.
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Parts commonly replaced
- Diverter valve
- NTC Thermistor
- External programmer
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