Ranges

Ranges

The range is perhaps the most versatile piece of cooking

equipment in a commercial kitchen. It can be used to

cook a wide variety of foods, primarily those requiring

the use of cookware such as pans, stockpots and skillets.

Many range units are also equipped with a conventional

or convection oven located below the cooktops, which

makes the unit even more versatile.

Cooking Process

The range cooks food by transferring heat to the

cookware, which in turn transfers that heat to the food

by conduction. The cookware is heated either by an

electric resistance coil, a gas or electrically heated solid-

top element, or by coming in direct contact with the gas

flame. Ranges can use a variety of cookware; however,

when solid-top elements or resistance coils are used, it’s important that the bottom of the cookware be flat to allow a good contact between the bottom of the pan and the elements. Rounded bottom pans reduce the amount of heat transferred to the pan.

Gas open-top units apply a flame directly to the bottom of the cookware. The chef controls the temperature by adjusting the height of the flame, which provides the visual feedback many chefs have become accustomed to. Gas units can typically be used with any type of cookware.

Solid-top units or flat-top units can be heated by electric resistance coils or gas burners. While these units take several minutes to preheat, they provide a very uniform temperature across the surface of the plate. Heat from the plate transfers to the cookware by conduction. Solid-top gas units are much less efficient than their open top counterparts because the plate must heat up before transferring heat to the cookware. Plus, with greater preheat time, these units are typically left on while other types of units could be turned off when not used.

Performance

Cooking on a range can be more of an art than a science. The experienced chef knows that it takes finesse to get the best performance out of a range. For this reason, less experienced food service operators can have a hard time producing consistent food product quality. There is no substitute for trial and error in learning how to adjust temperatures to cook properly and produce a tasty end product. In most cases, it’s important that cookware have a flat bottom that makes good contact with the hot top or electric resistance coils.

Electric vs. Gas

Cooking technique on a range is learned largely by trial and error. That is why chefs are resistant to change after perfecting their craft. Most prefer to use the same type of units that they were trained on. Chefs trained on gas equipment are likely to prefer gas, and reluctant to adopt electric ranges or even electric induction ranges. The same holds true for the experienced electric range users.

However, there are many factors to consider when selecting a range: first cost, food preparation productivity, ease of operation, and heat generation in the kitchen, as well as the energy source used: electricity or gas. Keep in mind that energy use only accounts for 3 to 5 percent of a food service establishment?s total costs. So, while one fuel may be less expensive in a BTU to BTU comparison, the best choice in cooking equipment is the one which minimizes total operating costs, not just energy costs. Features that reduce labor costs or result in higher food product yield will nearly always outweigh any energy considerations. Make sure you include all of these factors in any equipment evaluation.

Let’s take a closer look at the energy-use issues, remembering that comparisons should be made on the basis of similar equipment where only the energy input is being changed.

Electric ranges are generally considered to be:

More efficient, so they add less heat to the kitchen. This is heat that must ultimately be removed by the cooling system.

Electric units are less prone to cause fires when grease spills over onto the range.

They require less maintenance and less ventilation.

Electric induction units offer the highest energy efficiency, come up to full temperature very quickly, and offer precise temperature control. These units are also safer for food service operators because the surface never gets hot.

Gas or propane ranges are generally considered to offer the advantage of a cheaper energy source. Some chefs prefer gas units because they can control cooking temperature simply by adjusting flame height. Also, because many chefs are trained using gas cooktops, they will most likely prefer a unit which most closely matches their skills.

Components

Cabinet

Range equipment is available in many different sizes and configurations. Most units are 36 inches high and 30 to 32 inches deep and vary from 18 to 60 inches wide. Smaller units contain only 2 cooking elements while larger units can contain more than a dozen cooking elements. Ranges can be free-standing or mounted over an oven or cabinet base. Free-standing units often sit on a counter top and are sometimes called cooktops.

Open Top

Several different types of cooking elements are available for both gas and electric energy sources. The most common is the open-top element.

Open top gas burners have a steel or cast iron grate that holds the cookware in place. Gas burners located below the grate produce a flame that directly contacts the bottom of the cookware. Open burners provide precise temperature control by adjusting the height of the gas flame and require no preheat time. Each burner is individually controlled by a gas valve located on the front of the unit.

The comparable electric unit is commonly known as the open coil hot plate. The cookware rests on an electric resistance coil, which when heated, transfers heat directly to the bottom of the cookware. These units usually take a few minutes to reach full operating temperature and a few minutes to cool down when turned off. Each cooking element has a separate thermostat controlling temperature.

Hot Top

Hot-top ranges use the energy source to heat a thick metal plate rather than the cookware directly. These units are equipped with a 12 to 18 inch square plate about one-half to one inch thick. The energy source may be electric resistance elements or gas burners. In either case, the heat source heats up the metal plate. Cookware placed on this plate then heats by conduction from the plate. Since two separate stages of heat transfer are involved, these units are typically much less efficient than open-top designs. Plus, the plate can take 30 to 60 minutes to preheat and cool down. Therefore, chefs typically allow these units to continue operating even during slow cooking periods.

French Plate

The French plate falls somewhere in between the open-top and the hot-top. They are most often electric. The cooking element is a round plate about 6 to 10 inches in diameter. The plate heats up from electric resistance coils or gas burners mounted to the bottom. The plate provides even heat distribution and each "eye" is controlled separately.

Induction

The electric induction range is significantly different from the other types of ranges. Induction coils located under a ceramic surface induce an electric current in the cookware. These units offer precise temperature control and are more efficient because they heat the cookware directly rather than the range surface. The ceramic surface is durable enough to sustain heavy use even when sautéing. These units are by far the most energy efficient type of range available.

Accessories

Manufacturers offer a variety of optional features for the conventional range. Some units are combined with a conventional or convection oven, griddle or charbroiler. Some provide space for holding cooked food. Some manufacturers offer units with a combination of different cooking elements such as hot tops and open tops. Many ranges also have a shelf or a salamander broiler attached to the back of the unit.

Types

Heavy Duty

Heavy duty ranges are designed for large, heavy stockpots and other cookery. They are ideal for the high-volume production requirements in large restaurants and institutional and industrial kitchens. These units are typically smaller than conventional units, measuring 36 inches wide and are available in modular units with oven bases, open cabinet bases, or table tops alternatives. Configurations vary by manufacturer, but some include other features such as fryer sections, salamander broilers, ovens, and griddles.

Restaurant

Restaurant ranges are designed for a lighter duty cooking requirement than the heavy-duty range. Even though the total size of a restaurant range will generally exceed that of a heavy duty unit, they are more suitable for smaller operations and short order cooking. The larger size accommodates more cooking elements capable of supporting lighter cookware. Configurations vary by manufacturer. These units are available in lengths up to 72 inches and are often combined with a cabinet base or oven unit, salamander broilers, and griddles.

Specialty

A variety of specialty ranges are available to suit specific food preparation needs.

The Chinese range is built for wok cooking. Some of these have water spigots and drain troughs to make cleaning easier.

A stockpot range is designed for very large stockpots and is typically only 24 inches tall to allow the food service operator access to the large pot.

Taco ranges are also available for the unique task of preparing the contents of a taco.

Technology Types

New Technologies

Electric induction ranges represent the latest in technological advancement for the kitchen. These units heat quickly, offer very precise temperature control, and are considered safer because the cooking elements don’t get hot. These units are also the most efficient, transferring up to 90% of their energy to the cookware.

Efficiency

Saving Money

The initial cost of a range is rarely the most significant factor in making a purchase decision. Those who select light equipment due to lower cost often discover, after the fact, that these units are insufficient for the kind of production they had intended. A range should be chosen on the basis of the following six characteristics: capacity, versatility, temperature consistency, serviceability, ease and economy of required cleaning, and over-all dependability.

Here are some tips on how to operate the equipment in a way that saves money:

Make sure the bottom of the pot rests flush against the heating surface.

After the pot comes to a boil, turn the heat down to a level that maintains a simmer. Food will not cook any faster if you add more heat. That just wastes energy.

Cover the pot with a lid to retain heat.

Always cook at the lowest possible heat level that yields satisfactory food product.

Turn the unit off, or at least reduce its temperature when not in use.

For closed-top units, preheat only as needed.

Heat only the section of the closed-top unit being used.

Group pots on closed top ranges to use as little surface area as possible.

Here are some energy saving tips specific to gas equipment:

Adjust the flame until it is entirely blue. A yellow-orange tip means you are using too much gas and some of it is not burning completely.

Gas flames should just cover the bottom of the pot. Flames extending beyond the pot bottom are dangerous and waste money.

Other Information

Case Studies Regulatory - Electric and Gas Range Tops

Summary

Applying uniform test protocols (UTP) developed at its Food Service Technology Center, Pacific Gas and Electric Company (PG&E) compared the energy performance of eight range top models—four electric and four gas. Laboratory tests revealed that, when measured at full input, electric range tops operated at 67–81% cooking energy efficiency, more than double the 31–32% efficiency of the gas models.

Background

EPRI has supported an effort by PG&E’s Food Service Technology Center to develop American Society for Testing of Materials (ASTM) protocols for evaluating cooking appli-ances. PG&E has applied these protocols to test many types of food service equipment under both laboratory and production settings. By developing consistent, standard verification of equipment energy use, these tests are providing restauranteurs, utility service representatives, equipment specifiers, and manufacturers data for optimum selection and operation of food service equipment. One series of tests focused on range tops, a versatile appliance widely used in commercial kitchens for such tasks as stock-pot cooking, stir frying, and sauteing a variety of foods, including hot cereals, gravies, sauces, soups, and vegetables. The design of these useful appliances continues to evolve as commercial users seek more powerful and energy efficient equipment.

PG&E’s initial range top tests were instrumental in the ratification of an ASTM standard test methodology in 1994.This standard allows comparison of electric and gas commercial range tops based on such performance indicators as cooking energy efficiency and production capacity. Table 1 lists the models tested and the comparative criteria used in testing. The referenced PG&E reports provide additional data.

Approach

In the initial testing, PG&E staff compared energy consumption pat-terns of range tops under controlled laboratory conditions and in daily food production. Production testing took place five days a week, covering three meals each day. PG&E also tested three range top models after ratification of the ASTM standard. These models were tested only in the laboratory and not in a production setting.

Laboratory tests were conducted using a sauce pot filled with 20 lb of water to represent the typical cooking load. The first set of lab tests focused on determining cooking energy efficiency at both the half and full input settings by measuring the quantity of energy delivered to the food, expressed as a percentage of the total energy input to the range. The next set of tests deter-mined production capacity, defined as pounds of food cooked per hour. To compare induction cooktops with other types, researchers developed an efficiency calculation that included the energy to heat the cooking pot. Principal results from these and production tests are reported in Table 1; for other results, please refer to the referenced PG&E reports.

Results

As illustrated in Table 1, the electric range tops operated at cooking efficiencies of 67–81%, more than double the 31–32% of the gas models. Among the electric units, induction models delivered the highest efficiency, about 80%, while the hot top was the lowest, 67% at full load.

Productivity, measured in lb/h, was generally related to input energy. However, not all units have the same energy-productivity relationship. Induction unit productivity increased 46% while using only 25% more energy than open coils. Gas burner productivity increased only 36% for units requiring 50% more energy.

The production testing results were more variable and highly dependent on cooking patterns. The measured energy input for all models tested was within 5% of the manufacturer’s rated input.

References

Pacific Gas & Electric Company (510) 866-2844 Development and Validation of a Uniform Testing Procedure for Range Tops,

PG&E Research & Development Report 1022.95.20, October 1995.

PG&E R&D Report 008.1-90.24, June 1991.

PG&E R&D Report 008.1-92.10, September 1992.

PG&E R&D Report 5011.93.13, June 1993.

PG&E R&D Report 5011.93.7, December 1993.

PG&E R&D Report 5011.93.8, December 1993.

PG&E R&D Report 5011.94.4, October 1995.

PG&E R&D Report 5011.94.6, October 1995.

PG&E R&D Report 5011.94.7, October 1995.

PG&E R&D Report 5011.94.8, October 1995.

PG&E R&D Report 5011.95.30, February 1996.

PG&E R&D Report 5011.95.29, March 1996.

Electric Power Research Institute (510) 934-4212

food service Equipment Applications Handbook, TR-105991, December 1995.

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