Cast iron jet burners, fueled by either propane or natural gas, are similar to turkey kettle burners and are typically only used in outdoor brewing as per most municipal codes. Jet burners can not be used in closed firebox and require substantial air intake to function properly. If allowed to be used indoors, a vent hood is usually required. Orifice sizes are #63 for propane, or #54 for natural gas, and burners come with 32, 44, or 88 tips, with each tip producing approximately 10,000 BTUs. All burners are warrantied for 1 year.