Medium
P21 on Alpha Pro Tec Plus

Your boiler is struggling to control the temperature of your hot water, which may cause your taps to run cold or fluctuate in temperature.

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

Min. DHW ouput power

From this model's manual
Verified against the Alpha Pro Tec 24 installation & service manual, page 36.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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P01View →P02View →P22View →

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