A primer on the care and maintenance of Air Curtains in foodservice operations.

Air Curtains: An Overview

Air curtains create a barrier to help regulate temperatures and repel pests. Here is an overview of this foodservice equipment segment.

Foodservice operators commonly use air curtains, also referred to as air doors, to provide environmental separation, temperature control and insect repelling. The Food and Drug Administration (FDA) recommends the use of air doors specifically at loading docks and delivery doors to repel insects. A number of states require the installation of air curtains in certain areas inside food production facilities.

Air curtains consist of a powerful fan that creates an invisible air barrier, which effectively separates one environment from another. These units work by pulling in conditioned air, accelerating it and forcing it through an air curtain. Discharged air hits the floor and is directed outward and inward. Operators can opt to mount air curtains either horizontally above doors to blow air down or vertically on the door's side, which blows air across.

Recirculating air doors reuse air from a facility's interior to prevent the loss of heated and cooled air, helping to maintain an operation's interior temperature. Commercial operations, where doors need to be left open, tend to be the primary users of these products. Non-recirculating air doors separate two environments and/or prevent flying insects from entering a foodservice facility.

Air curtains, mounted above a door either on the interior or exterior, are available for openings that range from 36 to 144 inches wide. Operators can purchase a custom-manufactured unit for spaces up to 16 feet wide and 20 feet high. In-ceiling-mount, or recessed, versions also are available.

In certain cases, operators may need to hang an air-door system from a ceiling, regardless of the opening it will shield. When such a situation arises, manufacturers offer special bracket systems for installation.

Most air doors require between 115 volts and 480 volts to operate. Gas, electricity or steam can power the optional heating function most units feature. Air velocity ranges from 1,800 up to 5,100 feet per minute. Air curtains are available with adjustable air velocities and operators can purchase them unheated or equipped with electric, steam or hot-water heating units. Thermostats are available on heated models. Industrial models offer gas-fired heating options. Single- and dual-speed models, with either remote or automatic switches, are available. Motors range from 1/5 up to 20 HP.

Air doors are typically available in satin anodized aluminum, bronze anodized aluminum, stainless steel, white aluminum, powder-coated and custom-painted types.

Operators can specify units with separate control switches that determine a system's thermostat and air pressure, among other factors. For facilities prone to vandalism, such as schools and prisons, some air-door systems come with tamper-resistant features. An automatic door switch can now control operation of an air curtain when a door opens. Air curtains in high traffic areas can come with a time-delay control.

If an air curtain is installed over a sliding door, such as those found in many drive-thru windows, an automatic roller-door switch can be added. Such a switch turns the air curtain on when someone opens the window and off when the window closes. Similar door switches are available for hinged doors, as well.

How to Know When to Replace an Air Curtain

Depending on the unit and usage, air curtains can last anywhere from two to 30 years. But here are three signs that an air curtain may have reached the end of its service life.

Excessive Noise: If an air curtain is excessively noisy, a fan may be out of balance or a component may be broken inside. The latter is a sign that the unit needs replacing.

Inconsistent Airstream: If the air curtain's stream is inconsistent and the unit is not doing its job, it most likely has reached the end of its service life.

Ceases Operation: When an older air curtain is not operable, rather than repair the unit, it typically makes sense to purchase a new one.

Air Curtain Applications

Although air curtains can serve multiple functions, specific features and installation options can make certain units more effective for particular applications. Here is a closer look at the way foodservice operators use air curtains.

Air curtains keep two environments separate by controlling insects, smoke and aromas and regulating temperatures in kitchens, as well as above dock doors, walk-in coolers, drive-up windows or any opening susceptible to energy loss or temperature variation.

Air curtains also facilitate free-flowing traffic in facilities, can help maintain interior building temperatures as well as provide unobstructed vision as compared with plastic strips.

Air curtains can also work in conjunction with plastic strip doors or swinging plastic doors. These units are often used at the entrances of walk-in coolers and freezers. Another option is to position air curtains on front-of-the-house reach-in coolers. These air curtains help keep food in the coolers at safe temperatures while maintaining the temperature of the surrounding area.

These systems also are commonly installed at back receiving doors, in dock/warehouse doors, drive-thru windows and at customer entrances.

When negative air pressure is strong, air curtains also can be used in conjunction with makeup air fans.

Maintaining an Air Curtain

Like all equipment, air curtains need to be regularly cleaned and maintained to operate properly. Here are a five maintenance tips to help extend the service life of an air curtain.
Air curtains require minimal maintenance, but must be taken care of for optimum performance. Here are five key factors to consider when taking care of these units.

• Air curtains and plastic strip doors should be cleaned regularly. Air-cleaning filters are available for some systems that have a washable aluminum mesh. Periodically clean or replace these items.
• Depending on the environment, brush off air curtains every six months.
• Operators need to clean the unit's interior by wiping it down on a regular basis.
• Belt-driven air curtains require quarterly or annual belt checks.
• Electrical connects should be periodically checked.

Spec Check: Air Curtains

When specifying an air curtain, it's important to look at the main goal and where the unit will be used. Here are five factors operators and their supply chain partners should consider when specifying an air curtain.

There are a number of factors to consider when specifying air curtains.

Location: When installing an air curtain, operators should take into consideration its location in relation to staff and, especially, the front of the house. This is because different units have different noise outputs and air velocities, which can affect an operation's atmosphere and customers' dining experiences.

Type of Unit: Customer entrances should not be equipped with high-velocity air-door systems, as they can create an unpleasant entrance. Systems installed at customer entrances should include a heating function that can be turned on during colder weather.

Usage: The method in which the operation will use the air curtain determines the type of installation. Systems geared for pest control need to be mounted on the outside of a door frame, while those used for environmental separation should be mounted on the inside.

Placement: Operators need to consider the amount of room available for the air curtain, making sure it is not obstructing entrances.

Exhaust Fan: When used for environmental separation and temperature control, an exhaust fan may be required to provide proper air balance.

Energy Efficiency and Air Curtains

Because air curtains can help maintain heated or conditioned air temperatures, these units offer operational savings and a quick ROI.

By their nature, air curtains help save energy by creating a temperature barrier between two environments. In addition, air curtains were recently listed by the International Green Construction Code as a vestibule alternative and energy saver.

Also, for operators who plan to access a walk-in cooler frequently, an air curtain and strip door prevents cooled air from escaping, which will lower energy costs and extend compressor life.

Models are available that recirculate air, which adds to the energy savings.

In addition, units are available with control packages that include various speed and time options. This allows the installation point to select the air curtain's run time, automate the heat and other factors, which are designed to save energy.