723 Medium
Your boiler has detected that the water in the third heating zone is becoming too hot, causing the system to shut down that specific area to prevent damage.
Technical description: Overheating in zone 3
Typical repair cost: £120-280 (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 723 — no call-out fees, no surprises.
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Parts commonly replaced
- Zone valve
- Zone 3 temperature sensor (NTC)
- Circulation pump
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