In order for the kitchen extract system to function correctly, it is essential that an allowance is made for the provision of replacement or make-up air. This is acheived either by introducing mechanical supply air, or by making provision for natural infiltration (DW/172). This is particularly important when gas burning appliances are used in the kitchen. In this instance it is required to comply with gas regulations,
All make-up air systems include a filter system to ensure incoming air is not contaminated with airborne debris. If required the incoming air can be heated.