Henri Coanda was a Romanian inventor and engineer who contributed many ideas to the field of aeronautics. He spent some 20 years investigating the phenomenon that now bears his name.

When a jet is brought close to a flat or convex surface lying in parallel, the jet itself is attracted to the surface and stays close to it. It creates a zone of low pressure on the opposite side of the surface, which encourages entrainment of the medium present there.

AirMaster wall-mounted heat recovery ventilation units use the Coanda effect to distribute incoming air across a room. The inlet grille is placed as close as possible to the ceiling line, and care is taken to ensure that the ceiling in front of the MVHR unit is flat and clear of any obstruction which may deflect the air pathway. AirMasters deliver inlet air to the room typically at 19ºC, at a velocity of 3 – 4 m/sec. This air stays close to the ceiling for a throw of between 5 and 8m, depending on the model in question. As it moves across, this air jet entrains room air from below and is gently brought up to room temperature by the time it reaches the back of the room. There is a corresponding drop in air velocity, so that as the jet begins to fall away, it is moving at no more than 0.1-0.2 m/sec. This is how AirMaster MVHR units deal with the problem of wintertime draught.

Several conditions require being satisfied for the Coanda effect to deploy satisfactorily:

  • The velocity of the jet.
  • The distance between the jet and the ceiling.
  • The width of the jet exposed to the surface.
  • The absence of projections or other disturbing influences along the jet pathway.

AirMaster’s R &D programmes have solved the problems posed by the first 3 of these conditions.
Provided the room ceiling arrangement is suitable, the Coanda effect will continue to provide the answer to the significant problems posed by draught in UK classrooms today.

SAV Systems have a number of AirMaster wall mounted and floor standing air handling units installed at their Woking offices, all in regular operation. We would be happy to show you these, and reply to any queries you may have. Seeing is believing!

You can contact us on:

by phone: 01483 771910

by e-mail: webenquiries@sav-systems.com

We look forward to hearing from you!

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