Abstract: A heater control system is operable to modulate a heater of a building or warehouse or the like, in order to maintain the temperature rise of air passing through the heater at or below a maximum allowable temperature rise value. The maximum allowable temperature rise value is determined by a percentage or proportion of outside air being inducted into the heater and the type of heater, in order to limit the accumulation of carbon dioxide within the building. The control system is operable to modulate the heater in response to an outside air temperature, an inside or return air temperature, and the proportion of outside air to return air being inducted into the heater. Preferably, the proportion of outside air is determined by a position of a damper, which is operable to vary the relative flows of outdoor air and return air which are inducted into the heater.

Abstract: A control for an air treatment unit, such as a space heater having a heat source and an air handler that draws air from outside the space and from within the space in order to form a combined stream of air that is discharged to the space. The control includes a temperature setpoint control adapted to controlling the heating source in order regulate air temperature in the space to a particular air temperature setpoint and a temperature setpoint setback control that is adapted to decreasing the air temperature setpoint to a lower temperature setpoint during periods when it is anticipated that the space will be unoccupied. A differential pressure sensor senses a pressure differential between the space and outside of the space. A pressure control is responsive to the pressure sensor in order to control the proportion of air drawn from outside the space to air drawn from within the space.

Abstract: An improvement of the space heating system delivering a composite comprising of heated outdoor air, unheated outdoor air and recirculated indoor air into a building to counter a natural infiltration of outdoor air by modulating the composite air supply delivered to the interior of a building.

Abstract: A method for converting a direct fired gas heating apparatus from one having a constant volume discharge air flow characteristics to one having variable volume characteristics by the use of an internally recirculating volume discharge air flow increment.