D.78 Low
Your boiler is limiting the temperature it uses to heat your hot water tank to prevent it from getting too hot.
Technical description: Limitation of cylinder charging temperature in c
Typical repair cost: £0-120 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Protect yourself from future repair bills
A boiler cover plan would cover faults like D.78 — no call-out fees, no surprises.
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Parts commonly replaced
- NTC Temperature Sensor
- Wiring harness
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