Page 109 - WaterSense at Work

WaterSense at Work: Best Management Practices for Commercial and Institutional Facilities
Steam cookers, also known as food steamers, are commercial kitchen appliances
used to prepare foods in a sealed vessel that limits the escape of air or liquids below
a preset pressure. There are two types of steam cookers: boiler-based and connec-
tionless (i.e., without a central boiler connection).
Boiler-based steam cookers are connected to a central boiler, which delivers steam to
the heating compartment. Steam that does not condense on the food escapes as a
mixture of steam and condensate through a drain. In addition, some water is continu-
ously bled off from the steam cooker to help reduce and manage scale buildup. Most
manufacturers indicate that water supplied to the steam cooker should be under
parts per million (ppm) of total dissolved solids (TDS), or else bleed off should be
Boiler-based steam cookers also use large amounts of water to further condense
the steam and to cool (i.e., temper) the condensate water to less than 140ºF before
it enters the sewer system. Most boiler-based steam cookers offer a standby setting,
which maintains the boiler in a ready-to-use state. In many instances, the condensate
cooling water will continue to flow even when the steam cooker is in standby mode,
particularly if the condensate cooling water is controlled by a valve that must be
manually turned on and off. Some boiler-based steam cookers, but not all, do allow for
the condensate cooling water to be turned off while the steamer is in standby mode.
Steamers that are timer-controlled will automatically switch to standby mode at the
end of the set cook time, minimizing the amount of water wasted while the unit is not
in use.
Connectionless steam cookers can be either completely unconnected to any water sup-
ply or can be connected to a water supply to keep the water reservoir full. Connection-
less steam cookers have an individual reservoir where water is heated below the steam
trays to create the steam. These types of steam cookers are manually drained and
refilled and do not require a dedicated drain for condensate or the addition of cooling
or tempering water. A small amount of steam is vented through the top of the steam
cooker, but what is not vented or condensed on the food returns as condensate to the
reservoir. Connectionless steam cookers that are connected to a water supply have a
float valve that maintains the water level in the reservoir, but unlike the boiler-based
steam cookers, there is no continuous flow of water. This type of steam cooker is usually
as efficient as other connectionless models that are not connected to a water supply.
Steam cookers can achieve lower idle energy rates and reduce the amount of steam
needed and water used by reducing the temperature of the compartment during
standby mode, not continuously supplying steam to the cooking compartment, and
adding insulation. To address these efficiency advances in commercial steam cook-
ers, the U.S. Environmental Protection Agency (EPA) and U.S. Energy Department’s
DOE’s) ENERGY STAR® has developed voluntary criteria to qualify energy-efficient—
and thus, water-efficient—steam cookers. ENERGY STAR qualified models must
meet minimum cooking efficiency and maximum idle energy rate requirements.
Steam Cookers