Boiler displays E29, internal time clock or scheduling module fault.

Safety first: Turn off power before opening the control compartment.

• Reset time and date: Using the boiler or room controller menu, re-enter the correct time and date and check if the error clears.
• Check external timer: If an external time switch is used, verify its operation and wiring to the boiler.
• Replace backup battery: If the control has a replaceable battery for the clock, fit a new one of the specified type.

When to call a professional: If the internal clock circuit has failed, the control board may need replacement.