A critical piece of equipment lies well out of view of the guest, and is sometimes neglected until it has a problem. The machine and its workspace can take up to one fifth of the area of your entire kitchen, but it’s still not given the respect it deserves. Although the guest may not appreciate its service, they will surely feel its effect if it is not functioning. This machine has a significant effect on sanitation in a restaurant and ultimately guest satisfaction. The mystery machine, of course, is: the dishwasher.
The dishwasher may well be the most expensive single piece of kitchen equipment you ever buy. You’ll spend more than $20,000 for a dishwasher in a medium-sized operation. After you add in a clean dish table, soiled dish table, final rinse booster heater, and a few dish racks, it’s not uncommon to spend $40,000 or more. Since the dishroom 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.
Types of Washers
There are three basic types of dishwashers that are typically used in foodservice operations. Smaller operations may choose an undercounter machine which, generally, has a realistic washing capacity of about 40 to 50 full place settings per hour. The undercounter machine is primarily suited to smaller operations or snack bars using limited china, glasses, or flatware. The commercial undercounter dishwasher looks, at first glance, 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 are just over three minutes, to the fastest, which are approximately 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. Remember that most local health departments require separate clean and soiled dish drain boards, to prevent cross-contamination.
The next step up in dishwasher size is the door-type machine, which has a capacity of approximately 90 to 110 place settings per hour and is suitable for a small to medium size restaurant. Recently, 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 have controls mounted within the footprint of the machine. The typical door-type machine fits in a footprint approximately 24'' square. These compact units deliver a tremendous amount of power, some pumping more than 150 gallons of recirculated water over the dishes in a short 60 - 80 second cycle. In many cases, today’s machines conserve water, using only 1.2 gallons of fresh water per cycle. Most manufactures make their door-type units in either a straight through or a corner configuration.
Conveyor machines, the type that process dish racks continuously, are available in a wide range of capacities 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, which may be beneficial depending upon the specifics of your operation. For example, most manufacturers have one or two different pre-wash modules that are 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 about $5,000 to the price of a basic conveyor machine, but is a significant aid in cleaning heavily soiled dishes.
The next step to higher capacity and better performance is the addition of a rinse tank or an extended wash tank. Without a rinse tank to recirculate rinse water, machines typically use more water than those with a recirculating rinse. All machines have a fresh water final sanitizing rinse.
Conveyor machine lengths range in size from 44 inches to 10 feet. The rack conveyors can also be built in a circular configuration, which is convenient for some high volume operations. The scrapping area and clean dish drying area are all constructed together in one unit with a continuous loop belt.
Flight-type machines are a fourth dishwasher style and are generally used in institutions and extremely high volume operations with mass feeding requirements. Flight machines differ from their conveyor counterparts in that dishes are loaded directly onto pegs built into the machine.
The amount of dishes to be washed will be the major factor in determining the type of dishwasher you need. 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 it 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. The ratings for door-type machines, which are typically about 40-60 racks per hour and start at 200 racks per hours for conveyor machines, can be misleading. These numbers are computed mathematically and are not based on actual machine operation, which must allow for loading and unloading the machine.
Also, when manufacturers provide capacity figures in dishes or glasses washed per hour, use them only as a relative guideline when comparing various machines. The best advice is to rely on your own calculations based on the number of dishes you will use and how many can fit in a rack.
The dish quantity will be different for every operation since plate sizes vary and the mix of different china is different for each operation. A typical rule of thumb is that the actual production of a machine in racks per hour is about 70% 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 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'' x 20'' rack optimally.
Once the size and style of the machine has been determined, there are several other initial purchase decisions to make. Energy efficiency needs to be considered. As if it isn’t enough that dishwashers are very expensive and take up a lot of floor area, they are also energy guzzlers. Dishwashers are typically the single biggest energy and water user in an operation.
Energy Pros & Cons
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-degree water to do the job. Most manufacturers make chemical sanitizing versions of the different types of machines discussed above. 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. Operators must weigh the cost of the sanitizing agent against energy costs. Also, be aware that a benefit of the high temperature final rinse is quick drying. High temperature machines are also better able to break down animal fats and grease as well as lipstick on glassware and dishes. Most chemical sanitizing machines use sodium hypochlorite (bleach), in lieu of 180-degree water to chemically sanitize items being washed in the machine. It is critical to note that certain materials, including silver, aluminum and pewter, are attacked by bleach and cannot be washed in a machine set up for chemical sanitizing.
Reduced water consumption is important to many, and cost wise an important factor in many areas of the country. In addition to the chemical sanitizing machines, several manufacturers have developed machines advertised to reduce water consumption by 30% to 60% over their own standard similar sized machine. The idea is good, but when considering an energy saver, pay close attention to the washing capacity. Often washing capacity in number of racks per hour processed is also reduced substantially. You must evaluate your application carefully and determine whether it may be more cost effective to use a smaller machine rather than a water-saver dishwasher.
One water and energy saving feature standard in many machines, but may not be a part of an older machine, is sensors to shut down the wash and rinse pumps and exhaust fans when racks are not present in the machine. A sensor automatically activates the dishwasher when a rack enters the machine. The sensor feature helps maintain the temperature in the tanks and extends machine life by reducing the pump operating time.
There are also different levels of machine insulation, water savers and other options offered on machines by many manufacturers. You will need to weigh the initial costs with the projected savings. There are also three heat sources to choose from; gas, electric and steam. Most machines are now sold with electric tank heaters and booster heaters to boost the hot water from the main building supply at 120-140 degrees up to 180 degrees. Don’t rule out the new generation of infrared booster heaters which may be able to save money depending on local utility costs. These newly developed units offered by several manufacturers can deliver a lot of hot water efficiently without adding to the kind of heat to the dishroom that old gas heaters did.
Finally, make the dishroom as pleasant as possible for your dishroom staff. Dishroom work is hard and the area typically has the highest staff turnover of any restaurant position. Help the situation by purchasing adequate equipment for the expected volume, provide the proper ventilation or air conditioning, maintain the equipment well, and have the layout designed by a professional for the most efficient workflow. Don’t let the dishwasher to be your operation’s mystery machine. To adapt an old cliché, take care of your dishwasher and it will take care of you.