6.8.9 Gas – combustion air
Installations shall be provided with an adequate supply of combustion air.
Table 3: Combustion air to gas appliances
| Gas(1) up to 70kW net input | |
|---|---|
| England, Wales and the Isle of Man | If design air permeability is less than 5.0m3/h/m², then 500mm²/kW of the appliance is the rated (net) input If design air is permeability greater than 5.0m3/h/m²), then 500mm²/kW of the appliance is the rated input (net) over 7kW |
| Scotland | As BS 5440-2 (as England and Wales) |
| Northern Ireland | Up to 8kW rating, 450mm²/kW Over 8kW, add 450mm²/kW for each kW above 8kW |
Notes
1. Decorative fuel effect gas appliances should have a provision for combustion air complying with the relevant part of BS 5871 and relevant Building Regulations. (Generally, a minimum of 10,000mm²/kW of purpose-provided ventilation is required. Air vents should be direct to the external air or to an adjacent room or internal space, which has an air vent or vents to the external air of at least the same free area. Air vents should have an aperture dimension no smaller than 5mm).
Last updated: 2nd January 2024