Air curtains, also known as air doors, were introduced in Europe in 1916. They made their way to the U.S. in the 1950s and have been gaining recognition over the decades for their contribution to energy efficiency and comfort. An air curtain might be helpful to your operation as a means of not only improving energy savings, but also adding to the comfort of your employees.
The air curtain is a controlled stream of air, directed across the garage or dock opening to create an air seal. One of the major advantages of an air curtain is that, while separating your indoor operation from the outdoors, you have an unhindered view of traffic through the opening. An added benefit is that air curtains help curtail infiltration of flying insects.
You’ll also find air curtains installed in airplane hangars, drive-through windows, shipping and receiving doors, customer entryways, restaurant and at the entrance of refrigerated and cold storage rooms.
Air Curtain Types
The two major types of air curtains are recirculating and non-recirculating. Non- recirculating air curtains are the most popular, as they are easier and less costly to install. They also have lower maintenance costs. Recirculating types are used where there is continuous foot traffic, such as in a store or supermarket entrance. Although there are different designs, the recirculating air curtain might be built into an entrance, and discharge air from a grille on one side of the entryway, then collect it through a receiving grille on the other side and return it through ductwork to the discharge grille. The air stream in this type of air curtain should ideally be low velocity and unobtrusive.
How Air Curtains Work
Turn on the power, and air is drawn into the unit through an intake. It enters the fan housing, accelerated by a fan. The rushing air enters a plenum, which distributes the air evenly along the length of a discharge nozzle. Vanes in the nozzle help shape a uniform air stream with very little turbulence.
Non-recirculating air curtains are mounted horizontally above a door or vertically on the sides of the door, depending on the shape and size of the opening. A horizontal mounting is usually preferred, as it minimizes chances that the air curtain can be damaged.
When Mounting an Air Curtain
Before installing an air curtain, calculate the height and width of the opening, as well as clearance above the mantle. Other factors to consider are these:
- type of door;
- purpose of entry – whether service or customer, or loading dock;
- climate (exterior temperatures);
- prevailing winds; and drafts due to pressure differences
Air curtains are also helpful for maintaining the right temperature in different zones of your cold storage, freezer, cooler or refrigerated warehouse. Install an air curtain inside the facility or at the exterior door to save energy, prevent frost, prevent temperature transfer, keep the floor dry and reduce condensation by managing humidity.