| Dishwashers | |
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Commercial dishwashers, considered to be one of the largest water and energy consumers in a food service area, often use more than two-thirds of the overall kitchen water use. There are four main classes of commercial dishwashers: undercounter, stationary rack door type, rack conveyor and flight type. Each class of dishwasher may employ single or multiple wash tanks, and use hot water (high-temp machines) or chemicals (low-temp machines) to achieve final rinse dish sanitization. Requirements for machine class and size can be calculated by estimating the amount of traffic that will be served in the food service area. Water usage across commercial dishwasher classes does not appear to be directly related to the size of the machine and varies from .33 gallons per rack to 20+ gpr. A typical commercial dishwasher uses approximately four gpr. Using an appropriately sized, water efficient model will save a significant amount of water. | |
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Undercounter The smallest of commercial dishwashers, undercounter dishwashers, are best suited for small establishments of about 60 people. They commonly are used in nursing homes, churches, small food service areas and office buildings. The undercounter machines are similar to residential dishwashers in that the door opens downward with rack(s) rolling out onto the lowered door for access. A revolving wash arm handles the wash and rinse cycles, with a small holding tank being automatically drained after each cycle. An automatic timer controls cycle length. Undercounter machines come in both hot water and chemical sanitizing models, with optional booster heaters for the latter. Hot water machines are the most water efficient. | |
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Stationary Rack Door Designed to service 50-200 people, stationary rack door machines are the most widely used for commercial dishwashing machines. Door machines are used in schools, hospitals, churches, restaurants, catering businesses, fastfood establishments and as glass and utensil units in larger operations. These box-shaped machines have one or multiple doors that slide vertically for loading and unloading. Stationary rack door type machines are available in both hot water and chemical sanitizing models. Hot water machines are the most water efficient. These “dump and rinse” machines have a single tank for water and detergent, which are circulated in measured volumes and temperatures. Two revolving spray arms distribute wash solutions evenly over the dishes. Some stationary rack door machines have the ability to recycle rinse water to be used again in a wash cycle. |
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Rack Conveyor Rack conveyor, or c-line, machines use a motor-driven conveyor belt to move the rackloaded dishes through a large tank with separate wash and rinse compartments. Most widely-used in hotels, large restaurants, hospitals, schools and universities, these machines are well suited for service of 200 or more people, accommodating most heavy food service operations. Rack conveyors come in varying sizes, with available additions such as pre-wash units, sideloading trays, condensers and blower-dryers. A single tank holds the water and detergent at a regulated temperature. The wash solution is pumped through multiple spray arms (revolving or stationary) that run constantly once the machine is operational, regardless of the presence of a dish rack. The rack is then sent through the rinse compartment, where it is sprayed with 180ºF water by spray nozzles above and below the rack. Rack conveyor machines with multiple tanks differ in that some use stationary vs. rotating spray arms. The racks are then sent into a pump-driven rinse tank that rinses the dishes heavily. This process usually uses recycled water from the final rinse. All rack conveyor machines have a timer control for the speed of the conveyor to proper wash and rinse times. Water efficient measures, such as the installation of an electric eye sensor (that keeps the conveyor from running when there are no dishes on the racks) make conveyors more water-, energy- and cost-effective. | |
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Flight Similar in that they use a conveyor belt to move dishware, flight-type machines do not have racks. Rather, dishes are loaded directly onto the belt. Flight-type dishwashers provide high volume washing capability needed only in the largest institutional, commercial and industrial facilities. Variations in possible machine additions include power scrapers, power wash, power rinse, final rinse and blower-dryer. Water efficient strategies for these machines include the recirculation of final rinse water, electric eye sensors, extra-wide conveyors and low-energy built-in booster heaters. These additions can translate to water savings as much as 47 percent, while maintaining loads of more than 14,000 dishes per hour. | |
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| Information courtsey of: "Water Efficiency Manual for Commercial, Industrial, and Instutional Facilities" | |
