I am planning to fit a cooker hood to an internal wall, on an old and unused chimney breast. I would be quite difficult to run a duct to the external wall, and I am not keen to use a re-circulating kit with the hood. So I am wondering if it is possible to duct the hood into the existing chimney which would then be vented through the chimney stack on the roof. Is this compliant with regulations and is it feasible?