For this type of board (not this specific item as purchased)
The board is manufactured by ebm-papst Heating Systems B.V. - better known for fans etc. The board is subject to several failures but specifically produces a code '29' which means an 'internal communication failure'.
Unfortunately the company will not support this board (manufactured around 2005 - 2009) since it was used by Gledhill in a domestic heating system and Gledhill will not support it now either. Consequently a replacement board is the only answer at a high cost with no guarantee the fault will not reoccur on a new board.
After much communication with the manufacturer they will not supply a circuit diagram or offer a repair service 'out of warranty'. They will not supply information about how to programme/reprogramme the chip either, which could be the answer to the '29' code problem. Overall - not a good product. Fortunately, probably not used in great quantities.