It is notable that the Act: makes separate provision for the use of:
i) chimneys discharging from furnaces in buildings
ii) chimneys discharging from fixed boilers or industrial plant and
iii) other chimneys relates to the use of the furnace, fixed boiler or industrial plant and not its installation
In practice, chimney heights for CAA combustion appliances are often approved on the basis of the methods described in the Chimney Heights.