An air curtain, also known as an air door, employs a controlled stream of air aimed across an opening to create an air seal. This seal separates different environments while allowing a smooth, unhindered flow of traffic and unobstructed vision through the opening. Because air curtains help to contain heated or conditioned air, they provide sizeable energy savings and personal comfort when applied in industrial or commercial settings. Air curtains also help to stop the infiltration of flying insects.
There are two major types of air curtains: recirculating and non-recirculating (most common).
Non-recirculating Air Curtains
Non-recirculating air curtains are more widely used than the recirculating type because they are easier and less costly to install and have lower maintenance costs.
Recirculating Air Curtains
Recirculating air curtains are mainly used in places with constant foot traffic such as supermarkets and store entrances. Berner’s recirculating air curtains are called Air Entrance Systems, as they are built into the entrance, usually when the entrance is being constructed. They emit air from a discharge grille on one side of the door opening, collect it through a receiving grille on the opposite side and return it through ductwork to the discharge grille. The non-obtrusive wide stream of low-velocity air created by recirculating air curtains is more desirable for separating environments.
Once the power is on, air is brought into the unit through the intake, enters the fan housing and is accelerated by the fan. This fast moving air goes into a plenum, which allows for an even distribution of air along the full length of the discharge nozzle. Aerofoil-shaped vanes in the nozzle create a uniform air stream with minimal turbulence.
For efficient air curtain performance, the angle of the discharge nozzle must be set correctly. An air curtain nozzle should be adjustable to aim inward or outward up to 20 degrees from the opening.The air discharged through the nozzle creates a jet stream to the floor. Approximately 80% of the air returns to the intake side of the air curtain, and 20% goes in the opposite direction.
Non-recirculating air curtains can be mounted horizontally above the door or vertically on one or both sides of the door, depending on the space available and the height, width and physical characteristics of the opening. Horizontal mounting above the door minimizes the chances of damaging the air curtain. Protective measures should be taken if the air curtain is mounted vertically.
The proper size, power rating and features needed for a particular air curtain application should be selected according to the following considerations:
Berner air curtains require minimal maintenance. Scheduled cleaning, at least once every three months, will ensure the air curtain works properly and extends the life cycle of the product. Extremely dirty, dusty or greasy environments could require a more aggressive cleaning schedule.
Switch the power off at the service panel and lock the service panel to prevent power from being switched on accidentally.
Remove the air intake grille for access to the blower housing and motor(s). Remove the bottom access panel on heated models for access to the blower housings and motor(s). Vacuum and scrape (if necessary) to remove the built-up dirt and debris. For instructions for your particular model, consult the appropriate installation instructions.
The first U.S. patent for air curtains (air doors) was issued in 1904 to Theophilus Van Kannel. However, the first recorded air curtain installation was not made until some 12 years later. Air curtains became increasingly popular in Europe throughout the late 1940s and 1950s. In 1956, Erling Berner brought the most advanced European air curtain technology to the United States and formed Berner Industries, the foundation of today’s Berner International. The first Berner air curtains were sold in the United States in 1960 for use on cold storage doorways. Berner International has been developing, designing, testing and manufacturing air curtains since 1956.
To learn more about air curtains, take the free AEC Daily continuing education course online: “Air Curtains: Energy Savings & Occupant Comfort.”
This is an approved AIA course (1.0 LU/HSW hour), and it also qualifies for GBCI, RCEP and many other organizations’ continuing education requirements.