Terminals take many forms depending on the type of appliance and fuel used. In most instances a terminal is used to ensure adequate flue flow and will also alleviate the problems of downdraught and prevent debris collecting in the flue.

For balanced or power-flued appliances the terminal is generally located on an outside wall of the house, and it is mandatory that a shield is placed over the terminal if it exits the building less than 2 metres from ground level.