Foodservice Equipment Reports

ABCs of Air-Screen Refrigerators

If you’re running tray-line meal service, you’ve likely purchased an air-screen refrigerator in your time. These units differ substantially from regular reach-in refrigerators and those open merchandisers you see in retail cafés. Air screens are specifically designed to hold your chilled items at cold temperatures with the refrigerator door open during the tray run.

If you have a very old air-screen refrigerator in your operation, you might want to consider a new model as some nicely engineered advances are available now, including improved air flow, longer hold times when the door’s open and active defrost options. We’ll give you a rundown of characteristics to consider as you research the category. We’ll also share some common-sense do’s and don’ts to pass along to your tray makeup team when they’re working with these units.

Armed With Questions

If you’re in the market for a new air-screen refrigerator, make sure you have a good handle on how long your tray line runs each shift (i.e. how long that refrigerator door is going to stay open) and the actual ambient temperature of your kitchen.

Manufacturers will tell you that their units can hold foods cold (at minimum below 41°F; some brands hold foods at temperatures several degrees lower) with the door open anywhere from 45 mins. up to 2 hrs., but that’s usually if ambient conditions are ideal at about 70°F-75°F.

If your tray line runs long and/or your kitchen runs warm, you have options, including ultra-engineered models with heavy-duty compressors. One of the more robust units on the market gives you an open door time of 2 hrs. even with an ambient temperature of 100°F; if the kitchen’s cooler, say 80°F, that door-open time runs even longer to 4 hrs.

Note that most air-screen refrigerators feature ½-hp compressors, but heavier duty models will sport ¾-hp to 1-hp compressors. Compare that to the ¼-hp compressors on most standard reach-in refrigerators, and you’ll have an idea how air screens are powered up.

With time and temperature info in hand, you can start asking more questions, such as the direction of the air screen flow. There was a time when almost every manufacturer’s air screens blew from top to bottom only. But that particular directional flow on its own can be problematic because when your tray assemblers pull a pan half way out of the cabinet, they disrupt the air screen. That in turn jeopardizes the unit’s ability to hold temp. If your unit flows vertically only, you have to train employees to pull the tray all the way out of the cabinet.

Most units today blow the air screen horizontally, either right to left or left to right, to eliminate that issue. A few makers offer units that blow the air screen horizontally and vertically, creating a tri-directional air wall. Every manufacturer will be prepared to tell you about the technology behind its air screen and how it directs air across the front and throughout the cabinet. The important thing is to ask.

Defrost Issues

All refrigeration units have to defrost periodically. On most brands of air screens, automatic defrost is standard. Typically, a defrost cycle will come on every 4 hrs. or so.

Several manufacturers have taken a decidedly more proactive rather than passive approach to the defrost function, and the technology is worth looking into. These are a few of the options available in addition to automatic defrost:

Intuitive or smart defrosting is offered on several brands. What it does is adjust the length of time the auto defrost starts based on the duration of the last defrost cycle. If a defrost cycle should ideally take between 12 mins. and 15 mins., and the last defrost cycle only took 10 mins., the defrost function adjusts. Rather than going into an automatic defrost cycle in 4 hrs., it might push the defrost to run every 5 hrs. or 6 hrs. As soon as the defrost cycle takes 15 mins. or more, the defrost cycle schedule will shorten back to every 4 hrs. The upshot: Your unit defrosts when it needs to defrost—usually less frequently than every 4 hrs.—and that will help extend the life of the unit.

Another option, manual defrost, lets you start a defrost cycle by pressing a defrost button. Press it again, and the defrost cycle will terminate. With a timed override defrost option, the end user can set the unit to defrost between every 4 and 10 hours. Other options are available, as well, including defrosts triggered by the door being open longer than it should be. Again, ask for details.

Details, Details

What else do you want to consider? More and more units today sport glass doors instead of solid stainless, according to manufacturers. A see-through door lets staffers see what’s stocked with a quick glance. It’s just more convenient. One manufacturer offers Dutch doors, so your employees can keep one door closed—and more cold air in—during service.

Another feature to check—no-tip tray slides. Several brands will include additional guards on the tray slides, either as a standard feature or as an option, so that the tray stays level even when it’s pulled halfway out. No-tip slides help avoid huge messes. One maker has a tray slide that will slightly tilt the pans in a controlled way so that it’s easy for employees to grab items.

Some brands come with bumpers standard, others don’t. Whether or not you need a bumper wholly depends on the logistics of your facility. Will employees have to navigate these units any distances, through doors, down halls, etc.? Then a bumper makes sense.

Operational Do’s And Don’ts

Whether you’re in the market for a new unit or just interested in making the one you’ve got work at peak efficiency, you might want to review this list of do’s and don’ts when it comes to operating your air-screen refrigerator. These tips come from service expert Scott Hester, Refrigerated Specialist, Mesquite, Texas.

Load Cold Food: Too often, employees grab stock items and stage them on trays at room temperature before loading them into the air screen. If you load items that are above 41°F to 45°F, the warm stock increases the internal temperature of the unit. That means the refrigerator has to work harder to pull product temps down below 41°F. Bottom line: Train employees to pull meal components cold from your walk-in as close as possible to tray makeup time. That will help you get the maximum holding time out of your air-screen unit.

Don’t Overstock: The air screen itself, which, again, flows horizontally on most makes, horizontally and vertically on others, flows pretty gently and it’s easy to disrupt. So if your employees jam salads onto the trays with half the dish jutting into the air screen at the front of the cabinet, they’ll breach the screen and warm air from the kitchen will migrate to the cold interior. Not only will this make the unit work harder, you’ll jeopardize the safe temperature of all the food in the cabinet. You can wait for patients to complain about warm juice and milk, or you can train your staff to avoid overstocking the trays.

Watch Where You Put It: Take a look at where employees are parking the air-screen refrigerator along the tray line. Look up: Is there an air diffuser vent overhead? Is the unit located in proximity to the hood sucking exhaust from the cook line? Are there doors opening and closing nearby or fans blowing? Any of these air movers can disrupt the flow of the air screen, which you must remember is essentially your refrigerator “door” during tray makeup. And don’t put the unit next to your steam tables or steamers; humidity and refrigeration do not play well together. Try to situate the air-screen refrigerator in as still and cool a location as possible along the tray line.

Clean The Coil: One of the nice things about air-screen refrigerators is they’re built to roll, which gives your maintenance crew easy access to the coils for regular cleaning. Refrigeration works most efficiently if it can easily dispel heat from the unit. If the coil’s gummed up with greasy kitchen effluent and dust, you’re making it work harder. Ditto if you block heat dispersion with a garbage can. Just be aware.

Close The Doors: It may sound obvious, but make sure your employees close the refrigerator door as soon as they’re through with patient tray duty. Some manufacturers report they’ve seen these units left open(!) in between shifts. Operated properly, air screens hold the cold—give them every advantage.

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