It’s one of your most expensive equipment items but certainly not a glamorous one, nor one chefs rave about. Yet, it is a critical–if not the most critical–piece of equipment in every foodservice operation. The machine and its workspace can take up to one fifth of the area of a kitchen, but it is still doesn’t get the respect it deserves. Although customers may not appreciate its service, they will surely feel the effects if it is not functioning. Nobody seems to care too much about it...until it doesn’t work. The mystery machine is, of course, the dishwasher.
A dishwasher purchase decision needs to be an important one in your equipment buying strategy. You will spend $10,000 for even a small full height single rack machine that can serve an operation of around 100 seats. Larger operations need a rack conveyor machine. One of these units may cost $20,000 or more depending on size, number of tanks and accessories. After you add in a clean dish table, soiled dish table, final rinse booster heater and a few dish dollies and racks, it is not uncommon to spend more than $40,000.
Meanwhile, pot washers are sometimes similar in look to dishwashers but offer greater washing power to scrub off heavy and baked-on soils from pans and utensils. There are also the new soak and agitator sinks made by several companies. These units are more like sinks but do some of the scrubbing for the pot washing staff. First, let’s look at the dishwashers.
There are three basic types of dishwashers that are typically used in commercial environments. 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. These are similar to residential units though they’re much more powerful and faster.
The next step up in dishwasher size is the door type or full height single rack machine. These wash and rinse a rack of dishes in a little over a minute and can process about 90 to 110 place settings per hour. Many manufacturers now offer integral booster heaters to heat the final rinse water, and controls mounted within the footprint of the machine to reduce space usage. The typical door type machine fits in a footprint approximately 24" square but deliver tremendous washing power, some pumping over 150 gallons of recirculated water over the dishes during its short wash cycle. They also conserve water, using only about 1.2 gallons of fresh water per cycle. Most manufacturers make their door type units in either a straight-through or a corner configuration.
Rack conveyor machines, the type that process dish racks continuously, are available in a wide range of capacities, starting where the door type machines leave off and going up to several hundred place settings per hour.
Most manufacturers make a wide array of conveyor machines that are based upon different combinations of several standard modules. All start with a basic wash tank and then add modules depending upon the specifics of an operation. For example, most manufacturers have one or two different pre-wash modules that are very effective for scrapping and removing heavy soil from dishware.
Often the pre-wash temperature is lower than the wash compartment to remove rather than set protein soils like eggs. Using a pre-wash also helps effectively use detergent by not introducing it until heavy soils are removed from the china. A pre-wash unit typically adds some $5,000 to the price of a basic conveyor machine but is a significant aid in getting especially those dishes with heavy soil clean.
The next step up is the addition of a rinse or extended wash tank. Without a rinse tank to recirculate rinse water, machines typically use more water. All machines have a fresh water final sanitizing rinse. Conveyor machine lengths range from 44 inches to about 10 feet. Rack conveyors can also be built in a circular configuration that is convenient for some high volume operations.
Flight type 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.
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 advertise the capacity of their machines by the number of racks per hour it can handle based on their National Sanitation Foundation listing.
While the ratings are not meant to deceive, don’t be fooled by these theoretical capacities. These numbers are computed mathematically and aren’t based on real-world conditions.
Also, when manufacturers provide capacity figures in dishes or glasses washed per hour, use them only as a guide to compare machines. The best thing is to rely on your own calculations based on the number of dishes you will use and can fit in a rack. A typical rule of thumb is that the actual production of a machine in racks per hour is about 70 percent of the manufacturer’s rating.
Other initial purchase decisions to make involve energy efficiency. Dishwashers are typically the single biggest energy and water user in a foodservice operation.
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 chemical in the final rinse rather than 180°F water. Most manufacturers offer chemical sanitizing as an option in most units.
Manufacturers tout chemical sanitizing machines because of their low energy consumption but you should weigh that cost against the other benefits of high temperature final rinses, such as quick drying of dishware and more effective breakdown of fats and grease.
Most chemical sanitizing machines use bleach in lieu of hot water, so certain materials (silver, aluminum, pewter) can’t be washed in a machine set up for chemical sanitizing.
Reduced water consumption is another important factor. Several manufacturers have developed machines that reduce water consumption by up to 60 percent. The idea is good, but note the washing capacity, which can be reduced substantially.
The main differences between pot washers and dishwashers are the water pump motor size and the length of time for the wash cycle. Pot washer pump motors are up to five times more powerful, and the wash cycle up to four times longer.
Dan Bendall is vice president of Cini-Little International, a Maryland-based consulting firm.