BoilerFaultCodes 30-80 (M, L, M, L, M, M) Medium
Your boiler has detected an internal sensor failure affecting the hot water supply, meaning it cannot accurately tell if the water is hot enough to use.
Book a service
This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.
Technical description: Thermistor sanitary bypassed.
Typical repair cost £120-200 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like 30-80 (M, L, M, L, M, M) — no call-out fees, no surprises.
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Chaffoteaux Calydra 100 is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
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