Barbeque grills apply heat to food from a heat source below a food support surface in order to cook the food. The support surface or cooking surface for most barbeque grills is typically a metallic grate, a ceramic coated metallic grate, or an arrangement of multiple grates. The heat source radiates heat to the grates and through holes or voids in the grate. These grates are designed to provide conductive heat flow to the food by conducting or transferring received heat radiated from the heat source to the food. These grates also provide convective heat flow from the heat source below the grate via the holes or voids in the grate. The convective heat flow from the heat source rises and/or radiates to the food on the grate (i.e., food support surface) through the holes or voids in the food support surface (i.e., the grate).
A wood pellet grill is a type of barbeque grill that utilizes wood pellets as fuel for the heat source. Wood pellet grills are typically used as smokers or slow cookers due to their ability to maintain a stable, low temperature over a long period of time and general inability to provide controlled, high surge of heat followed by a reduced cooking temperature. A wood pellet grill has a fuel storage area or hopper that contains wood pellets. A small motor and gears power an auger system that provides metered delivery of the wood pellets from the hopper to a burnpot of the wood pellet grill. The burnpot is the location where the solid fuel combustion takes place (i.e., the heat source). Forced combustion air is routed through the burnpot by a combustion blower or fan in order to burn the fuel (i.e., wood pellets) in a clean and controlled manner. The fire in the burnpot burns under a heat shield that is designed to evenly distribute the intense and narrowly focused heat generated in the burnpot across the grill surface (i.e., food support surface or grates) and eliminate hot spots on the cooking surface. Generally, this greatly reduces convective heating of the food via direct radiation of heat from the heat source. Food can be applied to the cooking surface (i.e., food support surface) or grates and cooked as desired. The fuel (i.e., wood pellets) is typically ignited by an electrical resistive heating element that is in contact with the fuel or in close proximity to fuel that has been moved from the hopper into the burnpot during an ignition or startup sequence. A proportional, integral, derivative (PID) type controller controls the auger to control the fuel in the burnpot and temperature of the grill, and controls the resistive heating element during the ignition or startup sequence.
Wood pellet grills typically have maximum operating temperatures of 400 to 500° F. and therefore typically lack the ability to sear foods on the cooking surface (i.e., impart significant conductive heat from the support surface or grates to the food on the support surface). Wood pellet grills principally rely on indirect (i.e., not direct radiation such as infrared radiation emanating from the heat source to the food such as infrared energy emanating from a fire), convective heating of the food on the cooking surface to cook the food. Therefore, wood pellet grills tend to perform more like a conventional convection oven and less like a gas or charcoal grill. Wood pellet grills excel at smoking and/or slow cooking meats at low or medium cooking temperatures while imparting a distinct but pleasant wood cooked flavor. Even though an intense heat can be generated in the burnpot, the heat must be indirectly applied to the food on the cooking surface in order for the cooking to be properly controlled and even distributed to the food.