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June 2009
SPECIAL REPORT

Door-Types On Duty

Whether you're cleaning all types of ware or just need to scrub pots and pans, there's an effective, efficient door-type machine to fit your needs.

To see a variety of door-type machines, click here for the Door-Types Gallery.

By Mike Sherer

Preparing great food and serving it to your guests can be a lot of fun as well as profitable. The only problem is that someone has to clean up afterward, and in some operations, your dishroom may have been shoehorned into whatever space wasn't already taken by the cook line and prep areas.

Fortunately, the stationary, single-tank door-type warewasher cleans the devil out of anything and fits in even the most limited space. A typical machine can wash up to 60 racks an hour, or as many as 1,200 dishes, in a small footprint of a little more than 4 sq. ft., not counting feed and landing tables.

Are door-types right for you? A lot depends on the size of your stores, volume during peak periods, the type of food you serve, and the size and shape of your tableware.

First, the size and volume of your stores will determine whether you can get by with an undercounter dishwasher or need a rack conveyor or even flight-type dish machine. Door-type machines occupy the middle ground and make up a large percentage of the industry. Operations that find door-type machines most useful are full-service restaurants with roughly 150 seats; high-volume quick-serve units that use disposables and only need to wash pots, pans and parts; and larger stores that want a separate machine for pots and pans or even one dedicated to glassware.

Obviously, you need a warewasher that can keep up with the flow of dirty dishes from the dining area. Cycle times of door-type dish machines range from 55 secs. to 90 secs., which gives you an idea of how many racks your employees can push through in an hour. But how many dishes that equals will depend on your tableware. A restaurant with small 8" plates, for example, will be able to rack more dishes per cycle than, say, a Mexican restaurant using oval platters.

Finally, the type of food you serve may be a factor in your decision. Most manufacturers make both high- and low-temp chemical sanitizing machines. Hot water is effective at removing greasy, sticky soils—high protein foods like eggs and cheese, or greasy residue from fried foods, for example. Low-temp machines can clean light soil very effectively, and offer their own advantages (see below).

Your best bet: Do your homework and run racks of dishes from your operation through machines you're interested in to see which can handle what your kitchens produce.

The Energy Star Options
Most door-type dish machines are simple to operate—some models have a single start button—and built to last. About 18 months ago, the EPA's Energy Star program added these dishwashers to the list of commercial foodservice equipment it now qualifies. This means you can easily find additional energy and water savings by looking for equipment with the Energy Star label.

Energy Star-qualified dish machines are required to achieve or exceed ratings for energy usage during idle periods and water usage per rack. In the door-type category the idle energy rate must be lower than 1.0 kW for high-temps and lower than 0.6 kW for low-temps. And water consumption must be less than 0.950 gals./rack for high-temps and less than 1.18 gals./rack for low-temps. You can find a list of models qualified to use the Energy Star label at the Web site www.energystar.gov.

The ratings and performance of these machines are tightly regulated. To pass most local health codes, dish machines have to meet NSF/ANSI 3 standards. The ultimate purpose of warewashers is to clean and sanitize dishes and utensils, and NSF/ANSI 3 sets the parameters for wash and rinse water temperatures, chemical sanitizer concentration and so forth. Energy Star sets the bar for how efficiently dish machines achieve the NSF standards.

When you go shopping for a door-type machine, you'll see figures for water consumption and racks per hour that will help you compare one model to another, but we all know that how a machine performs in a lab isn't necessarily the same as how it performs in the field. What kind of energy and water savings you get in your stores, even with Energy Star-rated equipment, will depend on a host of variables, some of which you can control and others which may be more difficult to get a handle on.

For example, thorough scrapping before racking makes dishes easier to clean and keeps wash water cleaner longer. If you can train your employees scrap properly you'll see savings in detergent, water and energy.

Among the things you cannot control are local health department regulations, which might insist that hot water temps be limited to 110°F in restrooms so employees and patrons don't burn themselves. If your dish machine draws from the same hot water supply, your unit may use more energy heating wash water to the proper temperature. And in that setting a low-temp machine relying on hot water from the main water heater might not meet NSF standards or local health codes without a booster heater.

What To Look For
There are a lot of door-type models to choose from that will do the job for you. Here are some of the things to look for and a few of the options or alternatives available.

Styles. One of the first things you may notice is that there are two basic types of machines on the market. Though we refer to both here as "door-type" machines, on one style a handle opens two doors (on opposite sides if in a pass-through layout, on adjacent sides if situated in a corner). With the other style of machine, sometimes called a "hood-type," the handle lifts a hood above the rack, exposing it on three sides. Dishes may be more accessible in a hood-type dishwasher, but otherwise there's little difference between the two styles.

Several makers also offer double-sized machines that hold two racks. Many also give you the option of taller door openings on some models to accommodate sheet pans.

Construction, per NSF standards, is of stainless nearly throughout, but there are differences in design among the various makes and models. Double-walled construction of doors or hood retains heat and dampens noise. Insulation improves efficiency and quiets machines even more.

Wash Tank. The size and shape of the wash water tank can affect performance. A few models with slightly larger tanks retain more wash water heat and tend to be more efficient. And at least one maker claims that a deeper tank design does essentially the same thing.

Most washers these days are designed with coved corners in the tank for easier cleaning, a feature to look for.

Heaters. Wash water heating elements (or gas-fired burners) should have sufficient power to be up to the task of maintaining proper wash water temperatures (120°F to 140°F for a low-temp machine, 160°F for a high-temp machine). Most makers offer options for heater power depending on the temperature of your incoming water.

Most models also give you the option of a built-in booster heater to bring rinse water up to at least 180°F, per NSF standards. The advantage of a built-in is that it's prewired, pre-plumbed and usually doesn't take up additional space in your already cramped dish room. Again, size your booster heater properly to accommodate the rise in temperature you want it to produce.

Pumps. Wash pumps are where the rubber starts to meet the road in these machines. Most models use a 1-hp motor in a pump with a stainless impeller. Some models feature a 2-hp pump, making sure you've got plenty of scrubbing power. If you plan to use your machine for pots and pans, the extra power's probably a good idea. Be sure the model you choose uses a self-draining, vertically mounted pump so water doesn't sit in the pump between cycles or when the dishwasher's not in use.

Several models are available with rinse pumps, too. The advantage is that your final sanitizing rinse doesn't depend on building water pressure, which can vary, giving you a more dependable supply of fresh rinse water. Pumped rinse water also provides better coverage, makers say, ensuring that your loads are properly sanitized.

Spray arms and nozzle design are the other keys to performance in these warewashers. Spray arms should give you full coverage no matter what type of rack you use. Many manufacturers build machines with interchangeable upper and lower spray arms to make disassembly for cleaning and reassembling easier for employees. Wash arms and rinse arms are usually of different design, making it easy to put the right pieces back in place after cleaning.

Nozzles should be designed for maximum cleaning performance as well as clog prevention. No matter how well employees scrap plates, food and debris will end up in the wash water. Preventing that soil from jamming up nozzles is important.

Scrap Baskets. Some manufacturers offer one-piece scrap baskets, others two-piece units that double-screen debris and soil. Whatever the design, scrap baskets should be easy to get to, remove and clean. At least one line of washers is designed so that water flows in one direction during the wash cycle, trapping food and debris, then flows in the other direction when the tank drains, flushing soil out of the screen.

Taking Control As mentioned earlier, door-type machines are fairly simple to operate, with standard features like auto-fill wash tanks that sometimes require only the push of a button. Here are some other features you may want to consider.

Variable Cycle. While base models offer a single cycle, others offer options. Some models give you a choice of two or even three different cycles. In some cases, the variable is simply a longer wash cycle, while the rinse cycle remains the same. On other models, however, you can control both the time of the cycle and the wash water pressure, giving you more flexibility to wash everything from delicate crystal or glassware to scrubbing pots and pans.

Automatic De-liming. Some models have an optional de-lime cycle that automatically washes the inside of the machine with scale remover.

Detergent Dispensers. Several models have ports for plug-in detergent dispensers that automatically add the proper amount of soap to the wash water. In some cases you can get automatic dispensers for rinse additives, too.

Programmable Eelectronics. While less expensive base models still rely on easily interchangeable, reliable electro-mechanical controls, some newer, more expensive models feature electronic controls. These controls offer you some potential advantages that may help pay for the increase in cost. For example, controls provide a self-diagnostic tool that tells you if the machine needs service. Some can be programmed to give you exactly the wash cycle you need in your stores. And several models can communicate with PCs, letting you monitor and record HACCP data such as wash and final rinse temps in addition to giving you alerts when machines need de-liming or servicing.

Safety Features. Standard safety features on most models include a door switch that turns off the machine when the door is opened, and a low-water shut-off that turns off the heating elements if the water in the tank is too low. The door switch also lets employees start the machine every time they load a rack by simply closing the doors.

Features available on only some models or as options include a temperature interlock and a rack sensor. The former won't allow the machine to run unless wash and rinse water are at their proper temperature. The latter saves energy by running only when the machine senses the presence of a rack in the machine.

Special Features. Ask suppliers what features differentiate their models from others on the market. Some special features may be of interest. One manufacturer, for example, has a patent-pending system that removes steam from the hood at the end of the cycle so the dish room doesn't get as hot and humid.

Coming Clean Getting the best performance from your door-type dish machine is a matter of simple maintenance and a few sensible tips.

  • Make sure you provide at least 48" of worktable—enough to hold two racks of dishes—on either side of the dish machine. This will give your employees adequate feed and landing space for loading and unloading dishes.
  • Train employees to scrap dishes thoroughly before loading racks. The more soiled your dishes, the faster your wash water gets dirty and the more detergent you have to use.
  • Use the right dish racks. Racks that aren't properly sized for your tableware or glassware not only can prevent dishes from getting clean, but also may result in more chipped or broken tableware.
  • Use the proper detergent and rinse agents in the right amounts. If you're not using an automatic dispenser, make sure employees measure chemicals used in the machine.
  • Filter and treat incoming water if necessary. Most dishwashers, especially low-temp models, clean better with water that contains only 2 to 4 grains of hardness. A filtration system that removes sediment and some minerals will help. You may need a water softener, too.
  • Check wash and rinse water temperatures. Most machines have thermometers, but it doesn't hurt to check their accuracy from time to time.
  • Drain wash water, rinse out spray arms and empty scrap baskets between each shift, or more often if needed. Again, dirty water affects the machine's cleaning ability and can clog spray nozzles.
  • Wash the entire machine daily. Disassemble and clean spray arms; empty and wash scrap baskets. Leave the machine open to dry overnight.
  • De-lime the machine as necessary. Watch for a white haze on the interior walls and spray arms and take steps to prevent scale buildup.
High-, Low-, Which Way To Go? As we've mentioned, high- and low-temp door-types each have their own advantages, and only you can decide which will work best in your particular circumstances.

If your operation serves a lot of proteins or fried foods, you may want the enhanced performance of a high-temp machine. High-temps tend to use more energy than low-temp, but the more efficient Energy Star models will help save some of the difference.

Low-temp machines are good for a variety of applications where lighter soils are the rule, or where electrical service isn't adequate to power a high-temp machine. Many chemical suppliers also offer low-temp machines on a lease basis, meaning a lower upfront investment. Long term, of course, you'll have the cost of chemicals, but energy savings, depending on local utility costs, may provide an advantage over high-temp machines.

Compare performance by testing machines either in one of your operations or at a supplier's location, and with your own dishes. There are enough models on the market that you'll find one to fit your needs as well as your pocketbook.

To see a variety of door-type machines, click here for the Door-Types Gallery.

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