My turbomax plus 828e locks out under the following circumstances.1 If I draw hot water when the boiler is cold 2 If I try to heat up the central heating too quickly. It ignites and burns for 2 minutes and then the yellow light starts to go on and off 2 or 3 times then the red lock out happens. With the DHW demand lockout is similar but much quicker. If I increase the temperature in small increments I can get it up to temperature OK. The fault code is F29. The problem started after replacing the fan after it had burnt out. The problem is not due to faulty thermistors. i replaced all 3 with no improvement. The system pressure is well over 1.5 bar at all times. The diverter valve was replaces 12 months ago

Nigel Robinson, April 2011

When running the boiler at full rate, look through the viewing window, I believe you will see the flames baffle out, hence F29
It sounds like a classic case of the fan incorrectly fitted and flue not properly sealed between outer and inner flue.

You could also try running it with the front inner cover off, if it stays alight, it confirms what I suspect.

Don't run it with the front cover off any longer than you have to, it's just for confirmation of the fault.

Carefree, April 2011