Connectionless Steamers
By Spencer Sator, E Source Research Associate, www.esource.com -- Foodservice Equipment & Supplies, 9/27/2007
Replacing inefficient steam cookers represents one of the most substantial opportunities for energy savings in a commercial kitchen. There are an estimated 205,000 compartment steamers in foodservice operations nationwide. Of these, most tend to be traditional units that rely on a boiler to vaporize a constant inflow of water. The Food Service Technology Center (FSTC) estimates that 60 percent of these units waste enough water and energy to warrant replacement. Self-contained, or “connectionless,” steamers provide the most efficient alternative to conventional units with combined annual water and energy savings of up to $6,000 per machine.Connectionless steamers do not attach to any water lines. Instead, they rely on a manually filled reservoir that sits in the bottom of the steamer. Unlike traditional steamers, connectionless units recirculate the steam rather than venting continuously. This closed system produces a substantial savings in both energy and water. Connectionless steamers conserve additional water because they do not have a cooling drain. In conventionally plumbed steamers, water condensate drains from the bottom of the appliance. Because most municipal codes prohibit the draining of water hotter than 140°F., foodservice operators need to inject a substantial amount of cold water into the drain pipe before the water enters the sewer. In all, connectionless steamers use about two gallons of water per hour, compared with an average of 40 gallons for traditional models. Over the course of a year, equivalent-sized connectionless steamers can save more than 150,000 gallons of water when compared to inefficient older models. If all the inefficient boiler-based models were replaced nationwide, the annual water savings would be about 20 billion gallons — enough to supply roughly 210,000 households. The energy savings are also striking. A highly efficient connectionless steamer could save up to 11,000 kWh over a conventional model. If the entire foodservice industry replaced conventional steam cookers with highly efficient machines, the energy savings would reach 1.25 billion kWh — equal to the electricity consumption of about 115,000 households.
The increased water consumption of standard, fully plumbed steamers also has associated maintenance and upkeep consequences. Since they consume such prodigious volumes of water, these models develop significant mineral deposits on intakes, floats, elements, drains and valves. Left unchecked, these deposits can reduce the steam cooker’s efficiency and cause premature failure. Conventional steamers thus require strong chemicals to clean, more frequent service calls and/or the addition of expensive water filtration devises to reduce the impurities flowing to the machine.
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In addition to increased efficiency and decreased maintenance, connectionless steam cookers also offer kitchen managers a degree of flexibility in terms of workspace layout. A kitchen manager can place a self-contained steamer powered by electricity virtually anywhere in the kitchen. In contrast, older models must reside near water lines. Gas-fired models obviously offer less mobility, but there are still several locations in a normal kitchen where a connectionless steam cooker can reside. New restaurants save on construction costs because connectionless steamers require less plumbing infrastructure.
If kitchen managers consider a new steamer, a number of programs encourage them to choose connectionless models. Approximately 44 different utility rebate programs offer anywhere from $350 to $750 to foodservice operators who purchase highly efficient steamer technology. Because connectionless steamers are relatively simple machines, they don’t cost tremendously more than boiler-based steamers. Natural Resources Canada estimates that replacing old units with a high-efficiency connectionless steamer has a very rapid payoff time — less than eight months for both gas and electric models.
However, connectionless units do have some limitations. Some kitchen staffers might consider the need to manually fill the water reservoir a burdensome chore. Under normal circumstances, the water reservoir should only require one fill-up at the start of every day. But if a kitchen has very long hours or is extremely busy, it may be necessary to refill the reservoir in the middle of service, which could potentially increase cooking times. Also, features like forced convection, vacuum pumps and compartmental insulation continue to make traditional steam cookers more efficient. So, a new connectionless steamer has less energy- and water-savings potential compared to a newer, more efficient boiler-based model. Connectionless models also tend to have somewhat longer cook times. So while the technology undoubtedly saves significantly on operating expenses, it may not be the best fit in all applications. Foodservice operators should carefully compare the benefits and costs of replacing their existing steam cooker with a connectionless model before purchasing.
The Food Service Technology Center commissioned an independent study of connectionless steamers in a variety of real-world settings. The study can be viewed here.
