Exhaust fans are an integral component of commercial kitchen ventilation. If a wrong fan is chosen, the system can have inefficient performance and could lead to premature fan failure. These fans must be able to withstand heat and grease laden air and are made differently than an ordinary fan. The fan must overcome the losses of the system and be sized to move the correct amount of air. The fan must be best suited for grease applications while still maintaining air movement at higher static pressures is a centrifugal backward inclined wheel.
Positioning of the exhaust outlet is a top priority to avoid causing or contributing to local air pollution and to minimise any cross contamination with the supply system.
The following points should be considered when deciding upon the point of discharge:
The outlets should be positioned where ventilation emissions are dispersed without any hindrance. Exhaust outlets must be directed vertically, unless it can be demonstrated that it would be more advantageous to direct the outlet in other directions.
It is recommended that ‘side discharge’ type of cowls should not be used, as these results in higher static pressure, noise and the potential re-entry of the exhaust due to downdraught. Sufficient distance should be allowed between the exhaust point and any supply air intakes.