What does the Baxi H.01 – .21 fault code mean?

Your boiler is overheating because water isn't moving through the system quickly enough to be cooled down while it heats your water.

How much does it cost to fix Baxi error code H.01 – .21?

Typical repair cost for the Baxi H.01 – .21 fault is £120-280 including labour.

Check that all radiator valves are fully open

Temporary error – flow temperature increasing too fast in domestic hot water (DHW) mode, insufficient circulation or sensor error.

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Almost always a stuck diverter valve on combis.

Each noise points to a different fault.

Lockout fault with a reset-needed pattern.