Clean and Efficient

Dan Bendall

There is something new and revolutionary happening in warewashing equipment today. It still may look pretty much the same, but the equipment is more energy efficient than ever before.

At least three European dishwasher manufacturers have recently come to the US market. Each has products similar in size and capacity to those of their American counterparts. Each has a lot of similar features, but their point of difference is energy conservation. The Europeans have long demanded machines that are low electric and water users because energy and water costs are higher there.

To reduce operating costs, some of these European manufacturers have insulated their machines, which is an effective way to keep heat inside the tanks. Others have devised ways to reduce hot water consumption through engineered sensors on spray nozzles. Interestingly, one of the best new water saving devices has come from a major American manufacturer, which has developed a high temperature final rinse spray nozzle that uses far less water than other contemporary nozzles. The benefits are lower water consumption and much lower wattage electrical elements needed to heat the water. The savings in annual operating costs from these new features is likely to be in the thousands of dollars in a large foodservice operation.

Some warewashing basics
There are three basic types of dishwashers that are typically used in food service. Very small operations may be able to use an undercounter machine that generally has a realistic washing capacity of about 40 to 50 full place settings per hour. The commercial undercounter dishwasher looks, at first glance, quite similar to a residential style unit. The commercial unit, however, is much more powerful and faster than its residential counterpart. Commercial undercounter machine cycles vary from the slowest machines, which do their job in just over three minutes, to the fastest that are around 90 seconds. Do not try to use a domestic model in your commercial operation because it will not meet the strict sanitation codes required.

The next step up in dishwasher size is the door type or full-height, single-rack machine. The machines wash and rinse a rack of dishes in a little over a minute. The rack machine can process about 90 to 110 place settings per hour and is suitable for a small to medium size foodservice operation. Over the last few years many manufacturers have responded to the tight space constraints. The typical door-type machine fits in a footprint approximately 24 inches square. The machines being made today also conserve water using only, in many cases, 1.2 gallons of fresh water per cycle. Most manufactures make their door-type units in either a straight through or a corner configuration.

Rack conveyor machines, for larger operations, start in size where the door type machines leave off and go up to models that can clean several hundred place settings per hour. Most manufacturers offer a wide array of conveyor machines that are based upon different combinations of several standard modules. All machines start with a basic wash tank and then add other modules that may be beneficial depending upon the specifics of your operation.

The next step up to higher capacity and better performance is the addition of a rinse tank or an extended wash tank. Without a rinse tank to re-circulate rinse water, machines typically use more water than those with a re-circulating rinse. All machines have a fresh water final sanitizing rinse. Conveyor machine lengths range in size from 44 inches to about 10 feet. The rack conveyors can also be built in a circular configuration that is convenient for some high volume operations.

Flight-type machines are a fourth dishwasher style and are generally too large for restaurants. Flight machines differ from their conveyor counterparts in that dishes are loaded directly onto pegs built into the machine. Flight machines are generally used in institutions and extremely high volume operations with mass feeding requirements.

What to purchase? The amount of dishes to be washed will be the major factor in determining the type of dishwasher to purchase. When you look at machine capacities, you first need to understand and decode the manufacturers' ratings. Most manufacturers advertise the capacity of their machines by the number of racks per hour they can handle based on their NSF ( National Sanitation Foundation) listing.

Using low temperature or chemical sanitizer machines is one way
to save on hot water costs and reduce some ventilation requirements.

The ratings for door-type machines are typically about 40 - 60 racks per hour, while conveyor machines start at 200 racks per hour. However, those ratings can be misleading. These numbers are computed mathematically and are not based on actual machine operation that must allow for loading and unloading the machine. In other words, if a machine is rated at 200 racks per hour you should expect to be able to wash about 140 racks per hour assuming you have a constant volume of dishes to be washed.

The same is true for manufacturers' claimed capacity of dishes per hour. The actual dishes per hour may be even less than 70% since the claims are usually based on a relatively small dish or glass size that fits a 20"x20" rack optimally.

Once the size and style of machine has been determined, there are several other initial purchase decisions to make. Using low temperature or chemical sanitizer machines is one way to save on hot water costs and reduce some ventilation requirements. Chemical sanitizing machines use a sanitizing chemical in the final rinse rather than 180° F water to do the job. Chemicalsanitizers clearly have a place in the market, but they are not for all operations. Manufacturers tout chemical sanitizing machines because of their low energy consumption. You, as an operator, must weigh the cost of the sanitizing agent against your energy costs. Also, be aware that a benefit of the high temperature final rinse is quick drying of dishware. High-temperature machines are also better able to break down animal fats and grease as well as lipstick on glassware and dishes.

Don't forget, no matter which type of high temperature warewasher you buy, you'll still need 180°F hot water for the final rinse. For that you will need a high-wattage electric booster heater, steam heat or gas. The difference now is that the total electric load can be lower and the savings can go right to the bottom line.

DAN BENDALL is a principal of FoodStrategy, a Maryland-based consulting firm specializing in planning foodservice facilities. He is also a member of Foodservice Consultants Society International.