Patent ID: 8542987

Claim:
A heater comprising: a base formed with a receiving space for receiving a fuel material that is to be combusted, said base having a top side formed with an opening that is in communication with said receiving space; and a heating unit including a flow guide component disposed on said top side of said base and having a through hole that is axially aligned and in direct communication with said opening and that has a diametrical dimension smaller than that of said opening, and a plurality of angularly spaced apart spiral air passages disposed around said through hole to permit air externally of said flow guide component to flow therethrough into said through hole, each of said air passages having an inlet end distal from said through hole and a connecting end disposed in proximity to and in communication with said through hole, each of said air passages further having a width that is gradually reduced from said inlet end to said connecting end, and a heat-radiating pipe disposed to extend upwardly from said flow guide component and disposed directly above said through hole, said heat-radiating pipe having a diametrical dimension larger than that of said through hole and permitting flow of flue gas resulting from combustion of the fuel material in said receiving space therethrough.