The dishwasher probably uses more utilities than any other equipment in your restaurant. It probably also requires one of the biggest initial investments of any item in the kitchen. Dishwashers are also likely to be one of the more unappreciated appliances in your kitchen — at least until there is a problem.
The dishwasher purchase decision needs to be an important one in your equipment buying strategy. Not only does the dish room take up a lot of space in your kitchen, its centerpiece — the dishwasher — may well be the most expensive single piece of kitchen equipment you ever buy. You will spend $10,000 for even a small full-height single-rack machine. One of these machines can serve a restaurant of up to 100-120 seats. Medium-sized restaurants over about 120-130 seats generally need a rack conveyor machine. One of these dishwashers may cost $20,000 or more depending on size, number of tanks and accessories. Add in a clean dish table, soiled dish table, final rinse booster heater, and a few dish dollies and racks, and it is not uncommon to spend $50,000 or more. Since the dish room contains a sizable portion of your restaurant's overall equipment budget, it will pay to have a basic understanding of some of what is available on the market.
Three main styles for restaurants
Three basic types of dishwashers are typically used in restaurant operations. 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 undercounter machine is primarily suited to a very small operation or snack bar using limited china, glasses or flatware. In addition to production capacity, the undercounter machine is not well suited for production work because the ergonomics of bending and lifting make it inefficient. The commercial undercounter dishwasher looks, at first glance, quite similar to a residential unit. The commercial unit, however, is much more powerful and faster than its residential counterpart. Commercial undercounter machine cycles vary from the slowest units, which are just over three minutes, to the fastest, around 90 seconds. By comparison, a residential dishwasher may take over an hour to complete a wash and rinse cycle. Do not try to use a domestic model in your commercial operation because it will not meet the strict sanitation codes required. If you use a commercial undercounter machine, remember that most local health departments require separate clean and soiled dish drain boards, separated to prevent cross contamination.
The next step up in dishwasher size is the door-type or full-height single-rack machine. These 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 operation. Over the last few years many manufacturers have paid attention to the tight space constraints in small to mid-size restaurants. Many now offer integral booster heaters to heat the final rinse water and controls mounted within the footprint of the machine. The typical door-type machine fits in a footprint approximately 24 inches square. These compact units deliver a tremendous amount of washing power, some pumping more than 150 gallons of recirculated water over the dishes during the short wash cycle. The machines being made today also conserve water, often using only 1.2 gallons of fresh water per cycle. Most manufactures make their door-type units in either a straight-through or corner configuration.
Rack conveyor machines, which process dish racks continuously, are available in a wide range of capacity, starting in size 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 machines start with a basic wash tank and then add other modules that may be beneficial depending upon the specifics of your operation. For example, most manufacturers have one or two different prewash modules that are very effective for removing heavy soil from dishware. Using a prewash helps effectively use detergent by not introducing it until heavy soils are removed from the china. A prewash unit typically adds about $6,000 to the price of a basic conveyor machine, but is a significant aid in cleaning, especially dishes with heavy soil. To raise capacity and improve performance, you can add a rinse tank or an extended wash tank. Conveyor machine lengths range in size from 44 inches to about 10 feet.
A fourth type of dishwasher, the flight style, generally is too large for most restaurants so they will not be discussed in detail. 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.
Which one is right?
The amount of dishes to be washed will be the major factor 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. While the ratings are not meant to deceive, do not be fooled by these theoretical capacities. 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. 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 a constant volume of soiled dishes. The same is true for manufacturers' claimed capacity of dishes per hour. The actual dishes per hour may be even less than 70 percent, since the claims are usually based on a relatively small dish or glass size that fits a 20- by 20-inch rack optimally.
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. Chemical sanitizers 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. But operators must weigh the cost of the sanitizing agent against their 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.
Reduced water consumption is an important factor to consider. In recent years, several manufacturers have developed machines that reduce water consumption by 30 to 60 percent over their own older similar-sized machines. The new units save water with a simple innovation: changing the size of the water droplets in the final rinse phase of washing. It was found that using a different size water droplet significantly increased the heat transfer to the dishware, aiding in sanitation and in the process reducing water consumption. Sensors to shut down the wash and rinse pumps are a standard energy-saving feature in many machines. This feature alone may help your case for replacing an existing older model.
Other energy and water saving options are available on some machines. One feature to consider is water tank and door insulation, which helps retain heat. Several manufacturers are starting to bring to market “ventless” dishwashers. These machines eliminate the need for a ventilation hood over the machine. That alone can save a restaurant on air conditioning usage and the need to install ductwork and a fan. These units capture heat from the condensed water vapor to preheat the incoming water to the machine, which saves even more.
Buy the dishwasher suited for your restaurant. Knowing your operation's needs and what is available on the market will help your decision. Be sure to research and compare energy and water usage, not just initial cost of the equipment. When you get a new machine, take care of it. Perform regular preventive maintenance. Start appreciating your dishwasher and it will serve you well.
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. Bendall can be reached at 301-233-5226.