or exceeds the selected temperature application_number US 201213620357 A description various concepts will now be presented with reference to a wood burning fireplace plenum system for warming outside air drawn by a blower and warmed by thermal contact with the fireplace inner firebox however the concepts may also apply to gas ethanol and other fuel types in the following description of preferred embodiments of the present invention reference is made to the accompanying drawings that form a part hereof and in which is shown by way of illustration specific embodiments in which the invention may be practiced it is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention the detailed description set forth below in connection with the accompanying drawings is intended as a description of various embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced the detailed description includes specific details for the purpose of providing a thorough understanding of the invention however it will be apparent to those skilled in the art that the invention may be practiced without these specific details in some instances well known structures and components are shown in block diagram form in order.