What do the regulations say?The recommended volume of air extraction per room in the house recommended by the Building Regulations:
- Toilet/sanitary accommodation: 6 l/sec (22 m3/hr);
- Bathroom/shower room: 15 l/sec (54 m3/hr);
- Kitchen adjacent to hob: 30 l/sec (108 m3/hr);
- Kitchen without cooker hood: 60 l/sec (216 m3/hr);
- Utility room: 30 l/sec (108 m3/hr);
Low Voltage Airflow Fans - Be Extra SafeThe Airflow range of SELV (Safety Extra Low Voltage) fans fully comply with the current IEE wiring regulations 17th edition detailing special requirements for bathrooms. These well proven fans use a 12 volt electrical supply(which means that the siting of the extractor fans is possible within the permitted splash zones of those using washing facilities). Note also that it is now possible to install a 230 volt, IPX5 rated fan with a dedicated RCD in splash zones. Consult the IEE 17th edition wiring regulations for full details.
What Type of Extractor Fan do I need?Having considered the application of the ventilation required, it is important to select the correct type of fan to ensure that the requirement is met. It is not sufficient to fit just any extractor fan. It is important that the fan performs efficiently by extracting the minimum flow rate at the grille outlet as required by the latest Building Regulations. This is known as installed performance. Also, the number of bends and the length of duct attached to the fan will create resistance to flow that must be overcome to ensure adequate extraction.
You should first consider which type of fan will be best suited to provide quiet, efficient ventilation. This will be based on one of the following two general variants.
- The Airflow Centrifugal fans and Mixed Flow fans - these are are quiet, powerful and suitable extractor fans for wall, ceiling and window applications. They also work very efficiently against system resistance making them the perfect choice for ducted installations. Examples of such Airflow centrifugal / mixed flow fans:
- The Airflow Axial fans - these fans are ideal for through the wall and window applications. Providing high performance with a slim profile, they are suitable for use with ducting up to a maximum 2.5m ( 11m*) in length. Examples of such Airflow Axial Fans: