Combi ovens may not yet be a kitchen mainstay, but if you ask a chef to name the most productive pieces of equipment in their kitchen, the combination oven/steamer is at the top of most lists. The combination oven/steamer is a piece of equipment that can bake and roast like a convection oven; steam and poach like a steamer; and reheat or cook product without drying it out.
Combis are quite flexible. They can operate in any one of the three operating modes — steam, convection or steam and convection. Some models offer specialty modes using hot air and steam to defrost, rethermalize, poach or gentle steam and warm. Many types of red meats and poultry products are well adapted to combination cooking because they can be prepared so many ways. Steaming vegetables and fish also is accomplished easily. And some say their best pastries and rolls come from a combi unit.
The steamer/oven mode uses forced-air convection for even browning along with moist steam heat to reduce product drying. The combination mode is especially well suited for producing less shrinkage in meats than typical ovens. Breads and rolls are fluffier and have more oven spring than those baked in traditional ovens.
The combination oven/steamer takes up about half the area of separate convection oven and steamer units. The space saved can translate into cost savings. Using less exhaust hood stainless steel and the ongoing cost of exhausted air-conditioned air over only three or four feet of reduced length can represent a significant ongoing energy cost. Still, the typical combi is expensive.
There is a new type of combi that costs less, however. Several manufacturers have engineered a lower cost boilerless combi oven. The expensive boiler is eliminated and the resulting steamer/ovens cost about 15-20 percent less than the typically sized counterpart. The only drawback is slightly reduced steam output. In many cases, the difference is not noticeable. And a plus is that the boilerless units have reduced liming problems due to hard water.
Oven/steamers range from small-volume countertop units to floor-mounted roll-in units with large capacities for banquets or institutional use. Typical sizes are stated by manufacturers in standard steamtable pan (12" × 20") or baking sheet pan (18" × 26") capacities. Note that shallow 2 ½" pans are typically used in the sizing ratings. You will need to reduce capacity accordingly if using 4" or 6" pans for items such as casseroles or lasagna.
Most manufacturers make the more popular oven sizes, including the four to six 12" × 20" pan-capacity countertop unit; a seven to ten pan unit and the larger floor or stand- mounted 14, 18 and 20 pan models. The smaller units generally hold only a 12" × 20" pan or half-size baking pan. The larger units hold two 12" × 20" pans on each shelf or a single 18" × 26" baking pan.
All sizes and styles are generally available as electric units. Only some manufacturers produce gas units, which are usually more expensive than electric units and available only in certain sized models. Generally, the smaller units are only available for electric operation. If you are using an electric unit be sure to have enough power. For example, a ten steam table pan unit requires between 13 and 19 kilowatts to operate.
The quality of water going into the combi is vital. The majority of all service problems are related to liming or mineral deposit build-up. A water filter is usually recommend, and have your tap water tested for hardness. But don't be complacent just because you have a water filter.
When buying a unit, look carefully and buy only the options you need because the expense adds up quickly. Most units are fully stainless steel inside and out with a glass window. Some models have a built-in spray hose for washing out the interior. Meat probes are not standard with some units and should be purchased, especially if a lot of meat roasting is planned. Also consider a side shield. The side shield is used when the combi is next to other cooking appliances to prevent the unit's electrical controls from getting overheated. There are other more subtle advancements in combis, including enhanced fan design for more even air movement and better self-cleaning options.
Most any operation can take advantage of the oven's versatility and benefit from the wide range of food products that can be cooked in the units, yielding high quality results.
Dan Bendall is a principal of FoodStrategy, a Maryland-based consulting firm specializing in planning foodservice facilities. He is also a member of Foodservice Consultants Society International. He can be reached at 240-314-0660.