Air heater control

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. The control system monitors the temperature of the discharge air from the heater and modulates the heater to maintain the discharge air temperature below a value based on the maximum allowable temperature rise, the indoor and outdoor air temperatures, and the proportion of outdoor air being inducted into the heater. Optionally, the control may adjust a position of the damper to maintain the temperature rise below the maximum allowable temperature rise. The present invention thus provides a low cost control system which ensures that the temperature rise of air passing through the heater is maintained below the maximum allowable value for any given proportion of outdoor air being inducted therein.

Dependencies are inferred from the claim text.