IN THE HOOD- By: Carol Meres Kroskey

Article Courtesy of Pizza-Today Magazine

You may not give a lot of thought to the hoods in your kitchen, but they play an important role in providing comfort and safety for your employees and patrons alike. Choosing the correct hood for your heat-producing equipment also can reduce your energy bills. The main job of a hood is to take excess heat out of the kitchen,” says Bob Utech, general manager for kitchen systems at in Schofield, WI. “Depending on local fire codes, a hood’s secondary function is to house a fire suppression system. “There are two types of hoods,” Utech continues. “Type I hoods are used for grease and smoke removal. These hoods are installed over deep fryers, grills, or ovens that use solid fuel, such as wood burning ovens. Type I hoods not only must have grease filters, but also they need to include a fire suppression system, such as an Ansul system. Although some people might think its overkill, it makes sense to require these precautions if you think about cooking as a violent process. In many cases, you have young, inexperienced employees operating the ovens, fryers, and grills. However, most municipal fire codes recognize that a gas or electric pizza oven doesn’t really qualify as a grease-producing appliance’, even though it cooks cheese, sausage, and pepperoni. Instead, you can install a Type II hood, used mainly to remove steam or heat.”

The commercial kitchen hood worksheet/checklist provided by the Seattle Department of Design, Construction and Land Use specifically cites a pizza oven as an example of equipment that needs only a Type II hood for “steam, vapor, heat, or odor removal.” It also requires that the hood have a “permanent, visible label identifying it as a Type II hood.” In general, Type II hoods can be made of a lighter-weight steel than Type I hoods, which require a minimum of 18 gauge, and both can be made of type 304 stainless steel, aluminized steel, or galvanized steel. “Hoods have to be built to NSF standards,” Utech says, “and have to be cleanable, not porous. We recommend stainless steel not just for its durability and cleanability but for its cosmetic appearance.”

I’m Coming with You!

Some ovens come with built-in hoods. However, in general. hoods are canopies either installed against a wall or over cooking islands that hold conveyor ovens. While Type I hoods require grease filters, Type II hoods may include models with baffles to catch and channel steam condensation. “A V-bank-style hood pulls the heat toward the center,” Utech says. “Newer hoods designed for chain-driven ovens have a reverse V-bank that turn the baffles crossways to draw heat in from both ends of the oven.”
 

While hoods can be constructed by local contractors, Utech notes that installing factory-manufactured components can be a better —and more economical—choice. “Hoods are costed by the square foot or by the linear foot,” he says. “For a typical oven, the medium- to high-side cost of a hood ranges from $1,500 to $2,000, and about $1,600 for a fire-suppression system. Other variable costs can be around $2,000. “Operators don’t really want to spend a lot of money on hoods and ducts, and may choose a local contractor. But manufacturers use AutoCAD designs and laser cutters to make an affordable hood that meets all the NFPA standards and receives the UL 710 label that inspectors look for,” he says. “Local-built, non-UL hoods are held to stricter standards, and as a result, have to move more air.”

Need More Energy

For chain-driven conveyor ovens, the hood’s exhaust function is paramount. “Because they’re open at both ends, single-, double-, or triple- stacked ovens can generate as much as 120,000 BTUs,” says Utech, “compared to the average home furnace that uses 80,000 to 120,000 BTUs to heat a 1,500-to 3,000-square-foot space. If you don’t take the heat out of your space, you’ll have uncomfortable workers and guests. It’s not energy-efficient to retain that heat, because you’ll put more of a load on your air-conditioning system, and it can be a major expense to chill that air.”

Instead, an exhaust fan installed at the end of the duct from the hood draws up the heated air and exhausts it to the outside. Previously says Utech, building codes specified a fixed air velocity measured at 1,500 cubic feet per minute. “New NFPA 96 regulations, changed in 2002, let operators regulate the air volume based on need,” Utech says. “For example, if there’s free cool air outside, you should be able to use it to cool the inside. New hoods have variable volume controls, like a rheostat that allow you to mix inside and outside air to maintain a comfortable temperature.”

Depending on whether they’re factory-built or local-built, hoods can be installed in less than a day, says Utech, while construction and installation of the ducts can take two days or more, depending on how many stories the building is. “If you do have to put in a fire-suppression system,” he says, “the system needs to be installed at the same time as the hood. The system requires fusible links in the right spot to set off the system if needed, and the cylinders have to be charged with pressure. The fire suppression system also needs a manual pull station by the egress.”•