Effective kitchen ventilation depends on both the amount of makeup air supplied and how it enters the space. Diffuser placement and air distribution must work together to support hood capture performance. Low-velocity kitchen diffusers supply air to the occupied zone at low discharge velocities, helping to limit disruption to the airflow around the hood. Low velocity does not, however, mean low air volume.
Diffuser Placement: Hoods, Appliances and Workstations
Begin by identifying the hood footprints, cooking appliances and staff workstations on the floor plan. Use this layout to assess potential diffuser locations, paying particular attention to their proximity to hood edges and workstations. Nearby doors, pass-throughs and other openings also need to be considered, as they can create cross-draughts.
There is no substitute for checking the installation conditions:
- Diffuser clearances should reflect the ceiling height;
- The product’s air distribution characteristics;
- The manufacturer’s instructions and applicable codes and standards.
Establish these clearances during design and verify performance during commissioning.
Air Distribution: Direction, Coverage and Airflow
The aim is to distribute supply air where it is needed without disrupting hood capture. Avoid directing air across the hood’s capture zone, where it could deflect rising cooking effluent away from the hood. In occupied areas, air should be distributed evenly at low velocity rather than concentrated in a high-velocity jet.
Getting the direction, airflow rate and supply air temperature right helps balance effective capture of cooking effluent with staff comfort. The aim is to minimise disruption; actual performance depends on airflow patterns and how well the system parameters are matched.
Selection: Airflow, Velocity, Pressure and Noise
A diffuser’s airflow capacity is only part of the selection process. It must also meet the velocity, pressure and noise requirements at its intended operating point. Start by allocating the kitchen’s makeup air requirement across the proposed diffusers. Then use the manufacturer’s selection data to check discharge velocity, pressure drop and noise for each candidate size at the specified airflow rate. If velocity or noise is too high, review the diffuser size, number of units or airflow allocation rather than simply increasing the flow.
Maintenance and Commissioning
Ease of maintenance should be part of the selection criteria. Check that panels or baffles can be removed and that components are accessible for cleaning. Always follow the manufacturer’s cleaning instructions.
Once the system is installed, measure the airflow at each diffuser and use the appropriate balancing devices to bring it into line with the design requirements. Thorough commissioning helps reduce airflow imbalances and noise issues during operation.
Conclusion
Successful diffuser selection brings together placement, air distribution and operating performance. Consider where each unit will be installed and how it will deliver air, alongside its airflow, discharge velocity, static pressure and noise characteristics. Requirements vary from one kitchen to another, so always check that the chosen product is suitable for the application.
Choosing diffusers for your kitchen? Explore Halton’s kitchen diffusers for product details.
