Commercial kitchens rely on speed and consistency in the cook line, and convection ovens help achieve these goals. This equipment evenly cooks food using a fan to circulate dry heat at high velocities.
Another hallmark of convection ovens is their flexibility.
Best known for baking, operators also use these units for roasting, browning and rethermalizing. Due to the circulating air in the oven cavity, operators can stack pans without compromising the cooking process.
Operators can choose between direct- and indirect-fired convection ovens. With direct-fired, the burner sits directly under the oven cavity and pushes heat into the space. Here, the combustion products combine with recirculated air and come in direct contact with items being cooked. With indirect-fired ovens, burners do not have direct contact with recirculated air or products. Instead, indirect-fired units use a heat exchanger. Gas and electric ovens are available in a wide range of sizes in floor and countertop versions.
Units designed for full-size pans have cavity dimensions that can accommodate 5 or more standard 18-inch-by-26-inch sheet pans, while smaller half-size units work well with lower volume operations. These units feature interiors that can hold a half-size sheet pan. For higher volume, bakery depth convection ovens have a 4-inch deeper interior cavity. With this type, pans can be loaded in left-to-right or front-to-back positions for increased air flow.
Full-size convection ovens come equipped with either single or double doors that are typically insulated. Double-door ovens provide doors that open separately or a synchronized type where both doors open and close simultaneously. Doors can be vertical or horizontal. While one convection oven can take up as little as 10 square feet, operators can choose to double stack these units to save space.
Fans have one speed, a high/low two-speed option or can be intermittent to automatically switch fan direction when the oven door is open.
Because the air flow impacts how evenly food will brown in a convection oven, some units feature fans that circulate air in two different ways. A reversing air system with advanced controls also can improve performance with more even and accurate baking. Both standard analog and the upgraded digital controls provide virtually unlimited possibilities for recipe development.
Standard features for these units include stainless steel door seals; double-pane thermal glass windows; two-speed fans with high and low settings; interior lights; porcelain interiors with multi-position, removable rack guides; and mechanical dial controls, including cool-down functions and continuous
Prior to purchasing a convection oven, the operator should understand the application. This will make it easier to choose among the different types of convection ovens and their various options and features.
Size represents a basic consideration when designing a cook line as well. “With a bakery depth oven, sheet pans can go in either direction, unlike in a standard depth unit,” says Ray Soucie, design director, Webb Foodservice Design, Portland, Ore. “Also, a bakery depth oven comes off the wall more than the standard type, so it requires an overhang of the exhaust system to accommodate it.”
Soucie prefers models with coved corners inside and says it’s important to look at the number of rack shelf facings. “Because these ovens can be stacked, operators need to look at the height in relation to the hood for overhead clearance,” says Soucie.
For certain applications, a two-speed fan option becomes ideal. “For example, if cooking flan, there should be a low fan or no fan blowing. And muffins also don’t do well with high speed fans,” says Soucie. “Other options to consider are lights and ease of control with a cook-and-hold feature.”
He recommends double door pull handles, which open both doors at the same time, over single handles. “You shouldn’t have to cross the body to get food in the oven,” he says. “For double doors, make sure the pulley or chain is supported by the manufacturer’s warranty.”
Operators should do their homework before purchasing a convection oven, since units operate differently. “Look at how the air moves around the oven, since manufacturers approach air distribution around the cavity differently,” says Soucie. “Some units move air down a double wall, while others blow air inside the oven with a fan, and there are pros and cons with how the cavity heats up.”
Other key considerations include the finishes; cleaning and maintenance accessibility with casters and quick disconnects; and programmability.
Cleaning & Maintenance
Caring for convection ovens does not require too many tasks on the user level. While service life depends on usage, these units last 6 to 10 years on average.
“Fans on the back of these ovens should be kept clean and free of grease and dust, since these cool internal electrical components and keep wiring from hardening from oven heat,” says Tim Lochel, service manager, Philadelphia-based Elmer Schultz.
Clean convection oven interiors with a commercial grade oven cleaner and use an enamel-safe cleaner when necessary, Lochel recommends. “Caustic cleaners will cause enamel to peel off,” he says. “Each manufacturer will recommend a cleaning protocol, which is important to follow.”
On a daily basis, operators can clean oven interiors and exteriors with soap and water. Clean stainless steel exteriors with commercial grade stainless cleaners that staff can spray on and wipe off. “It’s important to avoid abrasives like steel wool, which can scratch the metal, cause pitting and subsequently rust,” says Lochel. “Anytime you can keep grease off the oven door and control area, you’ll extend the life of components. Grease will migrate into the control panel and cause a lot of problems.”
Use glass cleaner or soap to keep glass doors on ovens clean. “This should be taken care of on a daily basis, because grease can burn onto glass and discolor it,” says Lochel.
If product cooks differently than it has in the past or cooking times are inaccurate, those could be signs the oven needs servicing. “Uneven cooking means there’s a problem with the convection part of the oven or the fans,” says Lochel.
When an operator uses foil to cover food, the aluminum can get sucked into and wrapped up in the convection fan, which will cause problems. “The oven will make noise if this happens, and typically operators can pull the foil out themselves,” says Lochel.
Because these ovens are basic pieces of equipment, operators mainly need to keep the units clean. But it’s also important not to run the units at high heat for extensive periods of time or the operation will run the risk of compromising the service life. “If operators are not using the ovens, they should be turned off,” says Lochel. “Also, cleaning the cooling fans will extend the life of the unit.”
Signs of a breakdown include the convection motor
or fan failing, and the biggest cause is improper fan cleaning and overheating as well as the age and extensive use of the oven. “A breakdown can be prevented if cooling fans and air intake areas are clear of debris and grease,” says Lochel.
If an oven is between 6 to 10 years old and repair bills have become costly, it’s most likely time to replace the unit. “Motors are expensive to repair, and operators need to factor in repair and replacement costs to ensure it makes sense,” says Lochel. “Also, there are many variables to replacing a convection oven, including getting it into the building and installation costs.”