Make Mine A Combi

Ron Popeil’s famous multipurpose appliances have nothing on combination oven-steamers.

“The combi oven bakes, browns, roasts, steams, grills or even fries almost anything you throw at it,” a combi voiceover would say. “It proofs dough, cooks and holds a roast with less shrinkage, bakes in a third less time, steams vegetables in a flash, and cooks even delicate items like fish fillets to perfection.

“But wait—there’s more.” And there really is. Combis really do deliver amazing capabilities.

Combi ovens have been used in Europe for decades, and they got their first toehold in the United States more than 20 years ago. Since the turn of the century (makes us all sound old, doesn’t it?), combis have started to take off. As models became easier to use and even better at what they do best, institutions in particular—colleges and universities, hospitals, B&I—realized the benefits of owning a piece of equipment that can do many things, and do them surprisingly well.

The combi oven, it turns out, is sort of like the Ginsu knife of cooking equipment (though it doesn’t yet come with a can opener). But a lot of operators, including many of you, still balk at using combis. Primary among the complaints have been price (they’re more expensive than, well, non-combis), the perception that they require a degree in astrophysics to operate (they don’t), and they take up too much space in the valuable real estate of the typical chain unit (that’s changing).

If you didn’t make it to the National Restaurant Association Show in Chicago in May, you might not know that combi manufacturers have overcome most of those objections. And even if you did get there, you may not have seen the incredible array of new models and advances manufacturers are now putting out there.

Since we last wrote about combi ovens in 2007, in fact, at least three new models have been honored with NRA Kitchen Innovations Awards. In addition, several manufacturers have unveiled updated features and new models. A couple of manufacturers are coming out with new models later this year, so we can’t even tell you all the cool (or steamin’ hot) features that may be on the market soon.

So Easy A Caveman…

So, let’s start with objection number one. With apologies to Geico, combi manufacturers really have made this equipment easier than ever to operate. The variations on how you can combine moist heat with dry heat are nearly limitless, but digital electronics give you control of the cooking cycle. That’s what makes a combi oven so versatile.

At low heat, for example, you can proof breads, and gently poach or cook seafood or delicate desserts. Using the delta-T function on many models (which monitors internal temps of whatever you’re cooking and maintains an oven temperature a certain number of degrees above that), you can cook roasts with as much as 50 percent less shrinkage. Cooking with moisture and finishing with dry heat lets you roast whole chickens, “grill” steaks and turn out crisp fries without added fat.

The last time we sang the virtues of combis, much of the praise had to do with their programmability. Cooking cycles like the ones just mentioned are easy to program into many models. Ovens have memory for up to 250 recipes using as many as nine different cooking modes, so many models give you one-button operation for most of your menu items.

Manufacturers have made changes to controls in the past three years in a couple of areas, all designed to make operating the equipment even easier.

First, more are switching to icon-based control systems to get around language and training barriers. You can group recipes by type of product under these different icons—a fish for seafood, a broccoli floret for vegetables, etc. They’re making the interfaces more intuitive, so chefs can program them more easily, and so employees can operate them with a push of a button or two.

Next thing manufacturers are doing is adding the kind of technology customers already are familiar with elsewhere. Touch screens similar to those on cell phones and newer laptops, for example, allow you to program the oven like you would your Blackberry or iPhone. The screens also have the capability to show video, so your oven can walk an employee through the instructions for a cooking or cleaning cycle on a step-by-step basis.

Many models now come with USB ports as standard equipment, making it easy to download recipe programs from a laptop or a thumb drive. The units’ internal memories also enable them to capture and record HACCP data that you can download to a computer for record-keeping purposes.

Quite a few offerings also now have Internet capability, which means you can program them remotely from headquarters or a regional office. Being hooked up to the Web also means service technicians (or your own staff members) can run diagnostics on the equipment to determine if it needs servicing, de-liming, updates or attention of some other kind.

One manufacturer even added Bluetooth to its combis along with a barcode reader, thus winning it an NRA KI Award last year. Recipes can be scanned with the bar code reader and uploaded to the oven through Bluetooth. No need for a USB port or other type of direct connection. Cool, huh?

Sizing Up The Competition

Another area of complaint that manufacturers have responded to is size. Volume feeders love the ability to throw 10 or even 20 full sheet pans of product into a big oven that cooks fast. And the large ovens have gone over well in Europe because many operators there use combis for everything.

But for many operators, those big units are just too big. So more oven makers are adding half-size combis to their lines. Half-sizers accommodate half-size sheet pans or hotel pans in a range of capacities. They go a long way toward solving space problems in the kitchen because they produce food much faster than standard convection ovens.

But oven manufacturers haven’t stopped there. New models aim to convince you that there is a place in your kitchen for a combi. One manufacturer has a new line of combi ovens that includes a “space-saver” model. The oven is designed with a little extra depth to accommodate five full-size steam table pans. The control panel is positioned over the oven door instead of on one side. The result is an oven that’s only 21-5/8″ wide, so it takes up less linear footage on your cooking line (and under your hood).

Another manufacturer recently introduced a “mini” combi oven that easily sits on a countertop. The oven holds three half-size sheet pans or three 12″ x 20″ x 2½” steam table pans. Primarily designed for after-hours hotel or hospital room service, it’s ideal for cooking small quantities on demand, and could well find a place in a chain-store kitchen for the right application.

Look for other suppliers to introduce space-saving models in the future as combis find more acceptance in kitchens like yours.

Getting All Steamed Up

A combi oven, of course, is a combination convection oven and steamer, so it can cook in three modes—convection only, steam only or a combination of the two. True, you can get steam injection with some convection ovens, but a true combi oven can do two things those less expensive ovens can’t: Combis can function as a standalone steamer, and they can control the level of humidity in the cabinet during cooking.

The former is important because there may be times when you need a steamer in a pinch and either don’t have one or find yours tied up. The latter is what combi ovens are all about. Controlling the humidity in a convection oven while products are cooking allows you to cook things in a combi you might not think possible—crispy french fries and “fried” chicken, grilled steaks, poached fish.

And combi ovens do all that while providing a range of benefits along the way, like reducing shrinkage, producing moister food and better finished quality, and cooking most menu items much faster than traditional methods. Combis might even help you save on energy costs, depending on particulars.

The addition of steam to a convection oven is what makes it all possible. How that steam is generated varies by make and model. It’s also become more sophisticated over time.

Early combi ovens were large, cumbersome boxes that contained their own boiler-based steam generators. They quickly grew popular in Europe because despite their size, they can replace other pieces of equipment, requiring a smaller footprint (and a potentially smaller hood) in space-starved kitchens to produce the same amount of food. Many manufacturers still make combis with conventional self-contained steam generators, and while they’re more sophisticated than ever, as a category these steam-generator types still have some inherent advantages and disadvantages.

Their primary advantage is power. A virtually limitless supply of steam means you can steam batch after batch of food with almost no recovery time required between each. Disadvantages include the large volumes of water and energy most such models use, and the additional maintenance required, such as the need for more frequent de-liming. These models tend to be better suited for high-volume institutional feeders—resorts, casino hotels, banquet facilities and the like.

Most models now are boilerless, doing away with many of the problems attendant with self-contained steam generators. Some make steam with a heat source boiling water in a pan; others produce “flash” steam by spraying water onto the oven’s heating elements or a heat exchanger. The oven fan then circulates the steam in the cavity. Boilerless advantages include energy savings (up to 40%), water savings (up to 50%), and significant cost savings, with list prices of about half to two-thirds of traditional combis.

The tradeoffs? Not many. Recovery in steam-only mode may not be as fast as in traditional combis, so production capacity may not be as great. And since the heating element must be on to produce steam, it can be more difficult to cook delicate items at low temperatures. Another drawback is that spraying cold water on heating elements can potentially weaken them (not a problem in gas ovens in which water is sprayed on a heat exchange plate).

As for maintenance of boilerless units: They still need to be de-limed on occasion. And unless the incoming water is properly filtered, chlorine in the water spray and resulting steam can cause corrosion and pitting inside the oven.

One manufacturer has a new design that addresses this last problem. The oven has three shallow water reservoirs below the cavity and above the heat source (gas or electric). Each acts as a steam generator when heated from below. For convection-only operation, none of the reservoirs fills. For combi-mode, one or two reservoirs fill depending on whether the food requires low humidity (40%) or high humidity (75%). In steam-only mode, all three reservoirs fill.

Each of the reservoirs holds about a gallon, and the oven typically uses only about three gallons of water per hour in steam-only mode, dramatically less than a traditional combi, and about 50% less than many boilerless combis.

A Clean Fight

In keeping with the push toward making combi ovens simple, manufacturers also have focused on the part of oven operation that employees like least—cleaning. Ovens, whether combis or not, can get really dirty, and baked-on food and grease is hard to remove.

Most manufacturers have models with automatic self-cleaning cycles. Several have made it easier to activate a cleaning cycle, and a few have added features that let you make more efficient use of energy and water during the cleaning cycle.

In most cases, self-cleaning units have a built-in spray arm inside the oven cavity. Starting the cleaning cycle activates the steam-only function to loosen baked-on food. The wash arm automatically sprays detergent inside the oven, thoroughly cleaning it, then rinses and sanitizes it.

Most makers say their self-cleaning functions can get even ovens that have just roasted a full load of chickens almost as clean as new. On some models you have to start the self-cleaning cycle manually. On others, you can use the program keys to set the cleaning cycle to turn on whenever you want.

One manufacturer took home a KI Award in 2008 for a self-cleaning system that uses a special cartridge containing both detergent and rinse aid. Employees simply toss a cartridge in the oven, shut the door and start the cycle.

Others tout the fact that no special chemicals are needed to clean their ovens, saving you money, and allowing you to use “green” products that don’t harm the environment. Different manufacturers use different cleaning solution methods. Most use a liquid cleaner. You fill a reservoir in the unit, and it dispenses automatically.

Cycle times vary. A four-stage cycle on one model line, for example, is about 20 minutes per stage, or about 80 minutes total. Another manufacturer boasts a cleaning cycle of about 35 minutes. If you plan to clean the oven between loads, you’ll want a faster cleaning cycle than if you plan to clean it at the end of the day. Either way, the self-cleaning function typically will save you about $15 in labor every time the oven is cleaned.

To make ovens more energy- and water-efficient, a couple of manufacturers have recently added features to their self-cleaning units. One gives you a choice of eight different cleaning cycles, so you can pick the cycle that best reflects the level of cleaning the oven really needs. Another has the kind of features you’ll find on your dishwasher at home that allow you to skip the drying phase, skip the rinse aid and reduce water consumption.

Another feature being added to more models is an automatic de-liming cycle. Each uses a different method, so be sure to compare to see which would fit into your operation best. A few are entirely automated. Others let you manually start a de-scale cycle that automatically meters the proper amount of solution, and flushes and rinses the generator. Several models offer warning lights that indicate when a steam generator needs de-liming.

Note that even with a de-liming cycle feature, you probably still want to treat your water before using it in a combi oven. Have your water tested for minerals and chemicals, and use the appropriate water filters to help prolong periods between de-scaling and the life of your equipment itself.

Test Standards Coming Soon

Other notable developments in the combi oven category since last we wrote about them concern energy and water efficiency. The good news is that many models are doing a better job of conserving both. And perhaps even better news is that you’ll soon be able to compare the efficiency of different models more easily. New Energy Star specs likely will be finalized and approved this summer.

The Energy Star specs have taken more time to develop than a lot of people expected primarily because existing test methods, developed for use in retail supermarket applications, don’t make sense for foodservice. A broad coalition comprising manufacturers, utilities, folks at the Environmental Protection Agency and Pacific Gas & Electric Co.’s Food Service Technology Center have been wrestling with the issue for about three years.

The problem in developing a new test method has been twofold—defining what “combi mode” really means, and finding a food product to test that’s universal enough in the industry. Since there’s no consensus yet on the answers to those two questions, the new ASTM-approved test method won’t measure energy and water efficiency of combi ovens in combi mode.

The new specs instead will be based on a two-part test that will measure energy usage in convection oven mode only, and energy and water usage in steam-only mode. That will give you a way to compare models based on the equipment you’ll most likely replace with a new combi oven—convection ovens and steamers. And equipment carrying the Energy Star logo will make it easy for you to identify models that are most efficient.


Not that you have to wait for the new test standards. One happy byproduct of all the experimentation with various test criteria is that an awful lot of combi data have been collected. That means there’s a really good reservoir to help you compare models.

Rules of thumb? As usual, it’s the total package that has to be measured. But plusses include double-paned glass, thick insulation, tight door seals and good control over how and when steam is introduced into the cabinet. Other features to look for that will make a unit more efficient include things like a “closed” system and, if the unit uses a bi-directional fan, electronic braking to prevent motor burnout.

If you haven’t considered combi ovens for your operation yet, this is one of the best times ever to take a look. You may find a surprising use for one that saves you both time and money.

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