Abstract: A portable gas fired heater includes a combustion chamber having an air inlet and an air outlet. A low DC voltage (optionally AC voltage) fan or blower directs air through the combustion chamber so that the air is heated. Preferably, a vortex generator is located between the fan or blower and the combustion chamber such that air entering the combustion chamber swirls. The heater is designed to have a low center of gravity and thus difficult to tip-over. Nevertheless, several safety features are provided including a tip-over switch, thermal coupler, temperature limit switch, and a manual shutoff.