Standard under-fired broilers or charbroilers are medium- to heavy-duty units. They have the ability to cook large quantities of food by exposure to radiant energy generated by heating elements located below the grid. Charbroilers are available in countertop, cabinet base, or stainless steel frame models.
Charbroilers cook food in the same manner as an outdoor barbecue pit. The food is placed on a cast iron grate above the heat source, and cooking is achieved primarily with radiant heat and by conduction through the grate. The energy source may be either electricity, gas, wood or charcoal. As the food cooks, fats or marinades drip onto the coals or ceramics producing smoke. The smoke provides the characteristic charred flavor, while the hot grates create the strip marks familiar to charbroiled foods.
There are two types of under-fired charbroilers. One type allows the radiant heat source to heat a radiant to a cherry red color. The radiant, in turn, broils the food product. The other type of charbroiler uses a heating source above or below to heat lava rocks or ceramic briquettes. The rocks or briquettes then distribute the cooking heat more evenly than would the heat source alone. Some manufacturers use both methods to increase the efficiency and reduce preheat energy loss.
The broiler grate is adjustable to both level and tilted positions. Typically, the charbroiler is designed for the rear two-thirds of the grate to be hotter than the front section. Many standard models have grease troughs fastened to each blade in the cast iron top grates to provide an avenue for excess fat runoff and reduce flaming. Excess residual fat drains into a large grease drawer located in a cool zone for disposal.
The charbroiler, like an open range-top burner, consumes energy at a constant rate, which is dependent on the temperature control setting. Because the charbroiler has a significant thermal mass of heating material that requires preheating, it cannot be turned "on" and "off" quickly on demand.
Maintenance costs for the charbroiler are typically higher than for any of the other types of broilers. This is because the heating radiants are below the cooking surface of the open grates and are thereby exposed to the materials falling through the radiants.