Fireplaces, chimneys and flues

6.8.4Solid fuel – combustion air

Installations shall be provided with an adequate supply of combustion air.

Solid fuel appliances should have an air supply from external air, either directly or indirectly, to comply with statutory requirements and the manufacturer’s recommendations. Full details of ventilation requirements for all types of appliances are contained in relevant building regulations.

Table 1: Combustion air to solid fuel appliances


1 Where the fire has a canopy, the open air vents should be 50% of the flue area.
2 Where closed appliances use a flue fitted with a draught stabiliser, the total free area should be increased to 300mm²/kW for the first 5kw plus 850mm²/kW for the balance of the appliance output.