Abstract: A heater for heating air includes an inlet, an outlet, and an air duct between the inlet and the outlet. A fan and a heating element are positioned in the air duct. A first temperature sensor is positioned at or near the inlet and configured to measure a first temperature of ambient air at the inlet. A second temperature sensor in positioned in the air duct and configured to measure a second temperature of heated air flowing through the air duct. The heater is configured to control heating power and fan speed based on measurements taken by the first and second temperature sensors.

Abstract: A window fan is provided that includes a fan housing and chamber assembly. The fan housing includes a front panel with an air outlet and a rear panel with an air inlet and defines a central chamber. The chamber assembly is positioned within the central chamber of the fan housing and includes a cylindrical fan rotatably mounted within the chamber and driven by a fan motor. An air duct assembly is rotatably mounted within the chamber having an air duct panel that is moveable from an open to closed position such that the air duct panel, when in the closed position blocks the airflow through the window fan and permits air flow through the window fan when in the open position. The fan of the window fan assembly may be a cross flow blower fan.

Abstract: A portable space heater is provided having a heating assembly that includes at least one heating element positioned in front of a fan (defined by the direction of the air flow with the air blowing toward the front) such that the heating element is in linear alignment with the fan along the axis of rotation of the fan. The fan and the at least one heating element may be further positioned within a duct assembly that narrows as it approaches a front grill of the portable space heater.