A portable electric heater including a housing having a bottom wall with front and back portions, a rear wall, a pair of side walls each having front and back portions, a top wall with front and back portions, a divider wall having a given area, and a front grill wall. The rear wall, divider wall and back portions of the bottom, side and top walls define a chamber while the divider wall, the front grill wall, and the front portions of the bottom, side and top walls define a cavity horizontally juxtaposed to the chamber. A plurality of elongated quartz heater elements and a temperature sensor are mounted in the cavity, and an electrically energizable fan is mounted in the chamber. Defined in the rear wall are a plurality of inlet openings, and in the divider wall are a plurality of discharge openings having a combined area equal to less than 2.5% of the given area. Limiting the overall area of the discharge openings reduces in the cavity turbulence which can prevent the detection of hot spots by the temperature sensor.