WaterSense at Work: Best Management Practices for Commercial and Institutional Facilities
Combination ovens combine three modes of cooking into one oven: steam mode,
circulated hot air (i.e., dry heat) mode, or a combination of both (i.e., combi-mode).
The steam mode is used for rapid cooking of food items such as vegetables and shell-
fish. The circulated hot air mode operates in the same manner as a typical convection
oven and is traditionally used for roasting meats or baking. The combi-mode is used
to reheat, roast, bake, or oven-fry foods. Steam and combi-modes require generation
of steam, an energy and water-intensive process.
The amount of water used by a combination oven is primarily dictated by whether
it is boiler-based or connectionless (i.e., without a central boiler connection). Typi-
cal boiler-based combination ovens are connected to a boiler system that supplies
the steam. These systems can waste large amounts of water because they require a
continuous stream of water to cool the condensed steam before it is disposed down
the drain. They may also supply steam regardless of whether the oven is in operation.
In contrast, a connectionless combination oven has a self-contained water reservoir
and heat source to create the steam required for the cooking process. This eliminates
the use of a separate, central boiler system and saves energy that would have been
used to supply continuous steam. Connectionless combination ovens are typically
drained and refilled each day and do not require a drain of condensate or the addi-
tion of cooling water.
Operation, Maintenance, and User Education
For optimal combination oven efficiency, consider the following:
Use the oven’s programming capabilities to control the use of the different cook-
ing modes in order to minimize water and energy use, taking into account food
preparation requirements. Specifically, where possible, use the steam mode and
combi-mode sparingly because these modes consume water and significantly
increase energy use. Instead, maximize the use of the circulated hot air mode.
Turn the oven off or down during slow times or when not in use.
Keep the oven doors completely closed.
Whenever possible, maximize the amount of food cooked per use by ensuring
that the combination oven is loaded to its full capacity.
Make sure to replace gaskets when necessary and keep door hinges tight, so that
the doors stay aligned and provide a good seal to retain heat or steam.