Medium
10.iii on Chaffoteaux Celtic 24 HE

Your boiler is rapidly turning itself on and off because water is not flowing through the system correctly, causing it to overheat too quickly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Rapid cycling high/low or high/low/off - By-pass if fitted not regulated

From this model's manual
Verified against the Chaffoteaux Celtic 24 He installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Ensure all radiator valves (TRVs) are fully open to allow water to circulate.Check that the central heating valves underneath the boiler are in the fully open position.Bleed all radiators to remove trapped air that could be blocking water flow.

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Related fault codes

10.iView →10.iiView →

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