Spec Check: Combi Ovens

As their name implies, combination ovens can employ various cooking modes.


Units can operate as steamers. They also function in convection mode, using dry convective heat to roast, bake and finish cooking food. In addition, combis can rethermalize menu items as part of a cook-chill operation.

What sets these ovens apart? The flexibility available in combination mode incorporates both steam and convection heat. The benefits of cooking in a moist environment include retention of natural nutrients, increased food yield and a reduction in cooking times by up to 60 percent compared to traditional ovens.

"There can sometimes be a disconnect between those who purchase the combi oven and those who use it, so we've seen operators not know the full capabilities of this equipment," says L. Daniel Bendall, principal at FoodStrategy Inc., a consultancy based in Rockville, Md. "This is a very expensive convection oven, if an operator is not taking advantage of the steam features or combi modes. Training at the user level is crucial."

Full- and half-size combi ovens are available, in addition to countertop models. Sizes range from units that accommodate 4 half-size steam pans up to roll-in units that have a capacity of 40 full-size steam pans. Larger units can also accommodate from 6 to 20 full-size sheet pans.

These units feature stainless steel construction, although gauge and type of stainless vary by manufacturer. Most combi ovens include corrosion-resistant stainless steel exterior panels. Cooking chambers generally feature 304 stainless steel, since these areas are subject to potential water quality issues based upon cooking technology that integrates steam with convection heat.

Ovens utilize either basic manual controls or digitally programmable features and are available with and without a boiler. "Virtually everyone thinks this is a great multipurpose piece of equipment," says Bendall.

Specifying Considerations

  • Operations that require steam, convection or kettle cooking should consider using a combi instead. These ovens provide the same capabilities as a steamer, convection oven and steam kettle.
  • Assess the menu to ensure a combi oven can handle the operation's cooking needs and volume.
  • Rather than disregard using a combi oven due to its higher price, it can pay to look at the big picture. Because it can perform multiple functions, combi ovens can eliminate equipment redundancy in the kitchen, saving money and space.
  • Review the available physical space to make sure the unit properly fits in the designated area. This includes access to exhaust hoods and door clearance as well as adequate space between other equipment as needed.
  • When determining capacity and available space, operators should keep in mind that two stacked combi ovens will provide more cooking versatility than a larger, single unit.
  • Take into account labor needs and skill levels when deciding whether a unit with manual or automatic controls would work best. Some units are more complicated to operate than others, and newer ovens tie humidity in with temperature to eliminate the guesswork.
  • The construction of a combi oven varies from manufacturer to manufacturer. Operators should assess the gauge and type of stainless steel used in the unit's construction to make sure it is suitable for the operation.
  • These ovens require access to a water supply, drainage, electricity and possibly gas, so determining utility availability and connections are key, prior to purchasing a unit.
  • If an operation is short on labor, a self-cleaning model may be a good investment.
  • Operators need to determine the type of cleaning chemicals required, as some ovens will necessitate specific supplies that can be costly over the long term.
  • Combi technology is an investment and requires resources to assure that operators are able to take full advantage of the technology in order to achieve a strong return.
  • The technology for these ovens continues to evolve, so operators should take the time to learn about new cooking features, efficiency developments, smaller footprints, ventless options and enhanced control technology prior to purchasing.
  • Oven models are available with or without a boiler. If the foodservice operator will use a combi more like a steamer (continuous full-load steaming) a boiler-based combi may be the better option.
  • Automated cleaning systems are standard with most ovens, although they can differ significantly based upon the design and type of cleaning chemical. Operators should determine the level of cleaning that will be needed and choose a model with a program that can accommodate the type and quantity of cooking.
  • Cleaning chemicals also vary significantly. While some combis use cleaning tablets similar to the type used with residential dishwashers, others use liquid concentrate and sanitizing chemicals, which can be remotely pumped to the oven. The cost also can vary and is worth considering.

Common Specifying Mistakes

  • Some operators place commonly used water filtration on combi ovens, when that may not be the right solution. Test the operation's water before connecting the equipment. This will allow for the application of the correct water treatment. Corrosion damage to ovens based upon water quality will void the manufacturer's original warranty.
  • Because combi oven technology can provide greater function in a single piece of equipment, operators should use these units in lieu of, not in addition to, other equipment unless justified by the menu and production requirements.
  • Oversizing these ovens also is a common problem. The equipment should not be compared in size to traditional ovens or steamers. For example, a single cavity combi oven can out-produce a convection oven in addition to a steamer.
  • By the same token, operators should be careful not to put too much reliance on the combi. If there is not enough support equipment, speed of service and food quality can be negatively impacted.
  • When specifying a roll-in combi oven, the floor area and utility hookups must be taken into consideration.
  • Another common oversight is the plumbing needed for combis. Due to steam production, high temperature PVC and copper plumbing is required.
  • "We caution people not to oversize a combi oven," Bendall says. "Smaller ovens that accommodate six or ten pans are fine for most restaurants."

Combi Oven Options

Combis continue to utilize smarter technology so operators can focus on quality and presentation. Foodservice operators can choose from a number of options that can enhance the use of these ovens.

Most combi ovens include core cooking probes that monitor internal food temperature, assuring that proper food safety requirements are being met. Additionally, some units feature integrated HACCP capability, which allows the operator to either log or download HACCP data through a thumb drive interface or other means to be stored on a disc or in a computer folder.

New oven features include integral smokers that use real wood chips; integrated ventless hood technology that provides location versatility; and an automated grease extraction system for operators seeking alternatives to grease trap maintenance and safer grease removal and disposal.

Other recent combi developments include a system that captures heat and humidity in the oven cavity for increased energy efficiency, automated systems with different levels of cleaning, various power modes, new designs that eliminate side clearance restrictions; and LED lighting.

Combi Oven Versatility

When it comes to production, operators have benefitted from combi ovens' flexibility and versatility.

In addition to being incorporated into cooking lines as a finishing oven, these units are utilized for high-volume production, cook-chill and rethermalizing.

This equipment provides almost any type of cooking technique offered by a convection oven, steamer or kettle, including poaching, blanching, steaming, sous vide, rethermalization, roasting, broiling, oven frying, baking and braising. Some combi ovens also have an integrated smoking capability to produce both hot- and cold-smoked foods.

Because these units help consolidate kitchen equipment packages, streamline the production process with menu versatility, provide faster production times and reduce required kitchen space, the ovens have become more common in the fast-casual and QSR segments.

Combis also have replaced rotisserie ovens in a number of retail foodservice operations, due to the equipment's faster production speed and the improved food quality and longer product shelf life the units provide.

A Consultant's Point of View

Foodservice consultant L. Daniel Bendall shares a few thoughts and observations about combi ovens.
Combi oven training at the user level is crucial and sometimes doesn't happen.

  • If retrofitting and adding a combi to an existing space, operators need to consider a floor drain, since steam and water are involved. This is often overlooked and can be difficult to deal with when adding a unit to an existing cooking line.
  • It's important to note that power requirements are very high for this oven, since it's a heavy-duty, high-production piece of equipment. Gas and electric usage are both extensive.
  • Meat probes are great to have and are standard with some combis and optional with others. If a restaurant offers food that needs temperature monitoring, a probe is a must-have item.
  • With many models, the side of the oven with controls shouldn't be situated next to hot equipment, like a charbroiler or open burner range. This may cause the electronics to malfunction or burn out. There should be at least a foot of clearance.
  • Combi ovens require an exhaust hood, which is sometimes overlooked.
  • Regular preventative maintenance is essential for these ovens, since there are many components. It's important for operators to follow manufacturer recommendations.
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