Air Curtains

Written by DNS Business Solutions On 17-12-2020 04:12:22 | 0 Comments

Air curtains are a fan-powered device that creates an invisible air barrier over the doorway to separate efficiently two different environments, without limiting the access of the people or vehicles.

How air curtains work?

Generally, the air entering through the inlet grille, sometimes with filter functions, is compressed by internal fans and forced thought an air outlet, which is directed at the open doorway.

The filter protects the interior components (heat exchanger, fans, electronics, etc.) from dust and particles.

The fans of the air curtain can be direct or belt driven. The most frequently used types are centrifugal, axial and cross-flow.

Some air outlets and/or lamellas can be adjustable to increase the performance of the air curtain according to each situation.

Heated air curtains have a coil (electric, hot/chilled water, steam, indirect or direct gas, direct expansion, etc.) to heat or cool the jet. Heating is used to avoid people feeling a cold jet of air when crossing the doorway and also to heat the volume of air coming in at the entrance.

Most air curtains are installed horizontally, across the top of the opening, and air is expelled from top to bottom of the door. Vertical air curtains can be installed in one or both sides of the door. Horizontal installation integrated on the floor is the most effective in thermodynamic terms and at the same time the most expensive one to install and problematic where public pedestrian traffic crosses the doorway for obvious reasons. So, it’s only used in some special industrial applications.

Types of air curtains:

Recirculating: Recirculating air curtains are more efficient but the majority of installations are non-recirculating due to lower costs.

Non-Recirculating: A non-recirculating unit discharges the air to the environment. Otherwise recirculating collect and return the air from the discharged air.


  • Free access for disabled people (wheelchair) or people using baby strollers, trolleys, umbrellas, etc.
  • Help to control uncomfortable sensations of draughts
  • Increases available usable space on entrances
  • Free access for disabled people (wheelchair) or people using baby strollers, trolleys, umbrellas, etc.
  • Help to control uncomfortable sensations of draughts
  • Increases available usable space on entrances
  • Reduces the energy losses from the conditioned space
  • Reduce central plant capacity (heating/cooling)
  • Reduces the building running cost
  • Reduces the CO2 emissions
  • Increase visibility and avoid collisions because there isn’t a physical obstruction
  • In cold rooms reduces misting, dry out the doorway and prevents ice forming on floors
  • Easy evacuation through the exit doorway in case of fire or emergency
  • Act as a barrier against fire smoke (special application)

To achieve these advantages, it is necessary to select the right air curtain. If we select a wrong unit then the air jet won’t reach the floor and the separation of two adjacent areas will disappear. Then heated/cooled air will cross the doorway and we will lose energy and all other advantages.

Some people only care about the price and select a less performance or inadequate air curtain, sometimes purchase on other sellers’ recommendation. Being confident you should always compare the characteristics of air curtains, especially the kind of fans used and the air volume.

At the end if we calculate the amount of money spent on the air curtain and the energy savings, we will achieve that selecting the wrong unit can be more expensive and more over the client won’t be satisfied.

In conclusion, on open doorways it is highly recommended to use an air curtain because of many benefits. All studies and tests have proven that air curtains are effective. When an efficient air curtain is well installed it will save a lot of energy and at the same time the entrance areas will always remain climate protected, comfortable and free of draughts, insects, odours, etc.