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Dishwashers go high-tech
4/22/08 - Valerie Killifer
Until the first dishwashing patent was issued in 1850, washing dishes was a chore often loathed by those left with the dirty plates and silverware. That first dishwasher, a hand-cranked model made of wood, led the way for the first gas-powered model in 1911, followed by a freestanding unit with permanent plumbing in 1920.
Over the years, household and commercial dishwashers have undergone a technological evolution. Energy- and watersaving features now are important aspects of foodservice dishwashers.
As recently as 2007, dishwashers were added to Environmental Protection Agency's Energy Star program. Under the program, high-temperature, single-tank conveyor dishwashers must consume no more than 0.7 gallons of water per rack. Meanwhile, low-temperature dishwashers must consume no more than 0.79 gallons of water per rack.
Because of the energy and water used during the wash and rinse cycles, companies such as Hobart, Electrolux, Jackson MSC and Meiko have worked to develop energy and water-saving machines.
"Reducing rinse-water consumption cuts energy consumption in half," said Allen
Hasken, product line manager at Troy, Ohio-based Hobart.
Hobart started its water-consumption improvement-initiative in 2004 with the creation of an under-the-counter dishwasher that reduced the amount of water used per rack compared with previous dishwasher models. The company also introduced a patented-rinse technology that cut water consumption by as much as 75 percent in some machines.
Hasken said, in addition to reduced energy costs, operators are looking for machines that are durable, fast and quiet.
"One thing they want to make sure about is their dishwasher is something they don't have to worry about," he said. "When we test individual components, we test them to failure, and that helps us to establish a failure rate. These machines have lifecycles of 10 to 15 years and beyond."
High-temp vs. low-temp
Operators also must consider whether they want a high- or a low-temperature machine.
High-temperature machines, which wash dishes and flatware at 150 degrees Fahrenheit to
160Ëš and rinse them at 180Ëš, rely on heat rather than chemicals to sanitize plates and other wares. In low-temperature machines, chemicals are the primary agents for sanitizing soiled wares.
"Chemical machines will typically use more water than a high-temperature machine," said Todd Bell, an energy analyst at San Ramon, Calif.-based Fisher Nickel Inc., an engineering consulting firm and operator of the Pacific Gas and Electric Company Food Service Technology Center.
Bell said high-temperature dish machines use more energy, but the cost is offset by a decrease in the cost of chemicals. Additionally, high-temperature dishwashers have a better cleaning performance because they clean at a hotter temperature. Low-temp machines clean at an average of 125Ëš, even though manufacturers often will recommend a supply water temperature of 140Ëš, Bell said.
Since low-temperature machines use colder water during the washing process, they lack the heat necessary to remove baked-on food particles. To compensate for poor cleaning performance, operators or dish machine service agents often turn up the water heater temperature set point.
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"So now you've got 160-plus-degree water running through the whole facility," Bell said. "You've negated a lot of the energy savings associated with the low-temperature machine and the chemicals are designed to function at a certain temperature. When you increase the temperature, you increase the chemical usage, as well. If your chemical machine is not tuned properly, it could become more expensive to operate."
Hasken said chemical consumption is something companies will look to decrease over the next 10 years, while machines with built-in heat-recovery systems will become more popular.
Heat-recovery systems already are popular in Europe as is the manufacturing of dishwashing equipment with insulated doors and boosters, designed to keep heat in the dishwasher instead of dispersing it into the ambient air.
"Since European machines are coming into the market, there has been a lot of improvement in U.S. machines," said Marco Parisi, product manager for warewashing and high-productivity cooking at Swedish-based Electrolux.
Electrolux's heat-recovery system uses the steam generated by the machine as a free energy source to preheat incoming final rinse water. The steam generated by the machine heats incoming 50Ëš water to around 140Ëš, and an internal 40Ëš booster then heats the water to 180Ëš for the final sanitizing rinse. Less steam is dispersed into the ambient air, saving ventilation costs.
At the National Restaurant Association Show May 17-20 in Chicago, Electrolux will introduce its first North American warewasher with a built-in heat-recovery system. The company also manufacturers machines with insulated doors, although that style has yet to make a mark in the United States.
Parisi said it is up to the manufacturers together with the EPA to make the end users aware of the savings they can earn by using Energy Star-rated machines, "especially with the increase in energy costs that every operation is now facing."
