Convection With Conviction
All-purpose convection ovens get an Energy Star nod, and suppliers of full-size gas models find new ways to make an old workhorse smarter and more versatile.
To see a variety of convection ovens, click here for the Oven Gallery.
By Mike Sherer
Long known as a standard piece of equipment for a wide range of operations, the full-size gas convection oven is getting a new look from both manufacturers and operators.
For years, the major advantage of convection ovens has been this: They cook faster at lower temperatures than conventional ovens. When they were first introduced, suppliers raved about their versatility and ability to work with varied menus.
The challenge, though, was that while convection ovens could cook plenty of products, they sometimes dried out roasted meats, unevenly cooked more delicate baked goods, and even dried out rethermalized frozen foods if operators weren’t careful.
Fortunately, design tweaks over the years have addressed these issues and more, including performance and versatility. Unless you do high volumes of specialty menu items, like roasts, breads or baked goods that might require a specialty oven, a convection oven is still one of the most utilitarian pieces of equipment in a kitchen.
And these days, they’re more efficient than ever.
First, A Look At Energy Savings
The biggest piece of news to affect this category in recent years is its inclusion in the U.S. Environmental Protection Agency’s Energy Star program, and both gas and electric models are covered. Final certification specs were recently announced during the National Restaurant Association Show in Chicago.
Several manufacturers have been testing various models at the Food Service Technology Center in San Ramon, Calif., for the right to bear the Energy Star label. That should make it much easier for you to compare models and find the most energy-efficient ovens on the market. Energy Star models typically are among the top 25% most efficient.
In this story we’re looking specifically at full-size gas models, and Energy Star says standard models typically have a 30% cooking energy efficiency and an idle energy rate of 18,000 Btu/hr. To beat those numbers, the new Energy Star requirements for these units are a cooking efficiency of greater than 44% and an idle energy rate of less than 13,000 Btu/hr. (Energy Star also offers new specs for electric units, and those numbers can be found at http://tinyurl.com/EnergyStarOvens.)
The good news is that you’ll now be able to quickly tell if a full-size gas convection oven is energy efficient by looking for the Energy Star label. Unfortunately, at the moment none of the so-called "hybrid" models that add moisture to the ovenmodels we’ll review later in this storyare covered by the Energy Star guidelines.
The bulk of the market, of course, consists of models that fit within the parameters of the Energy Star specs, and the category’s inclusion in the program should be a boon to most of you.
Now read on for information on how to spec the full-size gas convection oven you need, found in The Basic Box; how to understand burner and control options in Turn Up The Heat; and how to take care of your ovens in Easy, Breezy Maintenance.
The Basic Box
The biggest asset in this business is a strong, well-built box that will stand up to use and abuse in your kitchen. When you’re shopping for a full-size gas convection unit, look for a strong frame and insulation to help improve energy efficiency. Solid mineral board is a good option than for insulating material.
Interiors of porcelainized steel will offer ease of cleaning, and coved corners will keep food from collecting easily. Still, ovens get pretty dirty, and baked-on food can be very difficult to remove. At least one manufacturer offers an enameled liner that catches drips and slides out of the oven for cleaning.
Most models are constructed with stainless front, sides and top both for appearance and ease of cleaning. If you plan on slotting ovens into a bank of equipment, less expensive options offered by some makers are models with baked-enamel side and top panelsonly the front is stainless.
Also typical are dual-pane glass doors in stainless steel frames. Designs vary; some models have a single door, others equal-size double doors, or 60/40 split doors, often with glass in the larger door. Glass panes, of course, aren’t as energy efficient as insulated solid doors, so many makers offer solid doors as an option. But chefs and cooks prefer the ability to check on product without opening the doors. And keeping the doors closed during cooking likely makes up for any energy loss of a glass versus solid door anyway.
Most double-door models are configured so both doors open when you pull on the single handle. Operated by chain and gear mechanisms, those likely to be sturdiest are often made with heavy-duty, permanently lubricated bronze fittings and hinges. At least one maker’s models, however, have double doors that can be opened individually.
Door configuration may be important to you in another way, and that is space. A single door will extend farther into the flow of traffic behind the cooking line when open. If your aisle is tight between cooking lines or cooking equipment and expediting, that may cause problems or accidents.
If space in your kitchens is at a premium, you also may want to consider footprint when you put together specs for a convection oven. Models range from about 36" wide to almost 4’. That can make a big difference in your equipment layout. Fortunately, most models are stackable, so you can double your capacity in the same footprint.
Most full-size models are designed to hold at least five sheet pans of product. Most also come with at least five oven racks, but models vary greatly in how those racks can be configured in the oven. Makers offer from as few as nine to as many as 13 rack settings. The more varied the products you cook in your ovens, the more versatility you may want in rack configurations. One manufacturer also offers a heavy-duty rack on ball bearings capable of holding up to 50 lbs. as standard equipment along with four regular wire racks.
Turn Up The Heat
Full-size gas convection ovens can be made to operate with natural gas or propane, and you’ll need to specify which you prefer when you order equipment.
You’ll also notice a wide range in power of gas burners from one manufacturer to another. Btus vary from about 44,000 at the low end to more than 80,000 at the high end. No doubt an oven with a higher Btu output will heat and recover faster when loaded with cold product or doors are opened during cooking. Two things to keep in mind, however: Ovens with higher output burners may be less efficient, and their temperatures may fluctuate more widely during recovery cycles. Lower Btu ovens may recover more slowly but can provide more uniform cooking temps.
To cover all the bases, one manufacturer gives you the option on certain models of high or low Btu input. A toggle switch lets you choose 60,000 or 80,000 Btus depending on product and load in the oven.
To improve efficiency and performance, several manufacturers have been playing with new designs and borrowing technology from other industries. In a typical gas oven, the gas is piped into a tubular or serpentine burner with holes along the top. The burner emits blue flame under the heat exchanger and cooking cavity, and a fan gives the hot air an assist.
Some models now feature in-shot burners, which are more akin to the fuel injector in your car, mixing air and gas in a chamber to maximize its combustibility. The result is a more intense jet of flame that can be directed or aimed at the heat exchanger or oven cavity, using gas more efficiently. Another manufacturer uses what it calls a "transverse flow" burner system, with burners arranged from side to side versus front to back. It claims the configuration, with air drawn through the front of the oven, distributes heat more evenly and is more efficient.
Fans, of course, make convection ovens what they are, as they move air through the oven cavity to improve heat transfer to the product being cooked. Fan motors typically range in power from ¼ hp to ¾ hp, with most either ½ hp or ¾ hp. More powerful fans have the capacity to move more air more quickly through the oven cavity. The downside is that all that air can dry out product, especially delicate items like baked goods or seafood.
Most manufacturers use two-speed fans with a switch that lets you control air circulation in the oven. That gives you the flexibility to cook more items with better results.
At The Controls
Base models still feature electro-mechanical controls, usually a simple on-off switch and thermostat with an indicator light to let you know when the oven is on and heating. More and more base models, however, also include timers with audible alarms to let you know when a cooking cycle has ended.
Another standard feature on most convection ovens is an automatic cool-down mode that runs the fan until the oven has cooled to a specific temperature. In some cases, the cool-down mode is activated by opening one of the doors.
On most models, however, opening the doors automatically shuts down the fan and burners so the oven isn’t inefficiently blasting heat into your kitchen while chefs rotate racks, check product or load and unload the oven.
When setting specs for your operation, be sure to note the temperature ranges and settings you use for all your menu items. Some convection oven models have a limited operating range of from 200°F to 475°F. While this may be adequate for most of the product you cook, it might not work for all. (Don’t forget that most items cook in convection ovens at temperatures about 50°F lower than in conventional ovens.)
If your menu includes items like breads that need to be proofed then baked, or entrée portions you want to cook off quickly at high temps, look for models with a broader temperature range. Some range from 150°F to 550°F, and one manufacturer produces a model that has a low-end setting of 77°F for
Most suppliers now offer models with electronic controls, a simple but significant advance that offers improvements in performance and efficiency. With a temperature probe, for example, you have the option of cooking to time or temperature. Electronic controls also let you set multi-temperature cooking cycles so you can proof and bake bread, for example, or cook and hold a roast. Some even let you program settings into the unit so all employees have to do when cooking a particular product is key in the setting.
Another advance some makers have included in certain models is a way to introduce moisture into the oven cavity, making them more like combi ovens. The feature helps prevent delicate items or frozen foods from drying out too quickly, can help proof and brown baked goods, and reduces shrinkage in roasted meats. In a pinch, some models even substitute as steamers.
Easy, Breezy Maintenance
Convection ovens require little in the way of maintenance, though you may want to schedule regular service calls as part of your warranty and to keep your oven in tip-top shape. Like any other piece of equipment, the key to good performance and long life is keeping your oven clean.
Baked-on grease and food is not easy to remove, but porcelainized interiors do make the job a little easier. Make sure you regularly schedule thorough cleaning, and follow the manufacturer’s recommendations concerning use of harsh chemicals and abrasives on oven surfaces.
The newer hybrid ovens that add moisture to the oven cavity have water hookups. Most models have sprayer hose attachments to make oven cleaning easier. One manufacturer’s oven actually has a dish machine wash arm inside with four auto-clean cycles.
To see a variety of convection ovens, click here for the Oven Gallery.