Abstract: A humidifier for use in a central HVAC duct. The humidifier includes a water delivery system for applying water to an evaporator pad, a drain system for removing excess water that is not evaporated, and a control system employing two temperature sensors directly measuring the temperature of the air before and after the evaporator pad. The control system uses the two temperatures to adjust the water flow across the pad by cycling the water delivery system so that drain water is minimized while maximizing the evaporative capacity of the humidifier thus satisfying the humidification load as quickly as possible with the least amount of drain water. The humidifier may have either an integral fan or a flow-through housing for passing air across the wetted evaporator pad to increase the humidity level of the air.

Abstract: A humidifier for use in a central HVAC duct. The humidifier includes a water delivery system for applying water to an evaporator pad, a drain system for removing excess water that is not evaporated, and a control system employing two temperature sensors directly measuring the temperature of the air before and after the evaporator pad. The control system uses the two temperatures to adjust the water flow across the pad by cycling the water delivery system so that drain water is minimized while maximizing the evaporative capacity of the humidifier thus satisfying the humidification load as quickly as possible with the least amount of drain water. The humidifier may have either an integral fan or a flow-through housing for passing air across the wetted evaporator pad to increase the humidity level of the air.

Abstract: An air circulation system for use with or without ductwork having an outside air stream and a return air stream includes a controller and a return damper apparatus operatively connecting the return air stream to the controlled environment. The air circulation system further includes a heating unit and an air mass sensor disposed adjacent to the return damper apparatus. The air mass sensor selectively and directly detecting a ventilation rate of air moving through the return damper apparatus and communicates the ventilation rate to the controller which selectively modulates operation of the heating unit in dependence upon the ventilation rate.

Abstract: An air circulation system for use with or without ductwork having an outside air stream and a return air stream includes a controller and a return damper apparatus operatively connecting the return air stream to the controlled environment. The air circulation system further includes a heating unit and an air mass sensor disposed adjacent to the return damper apparatus. The air mass sensor selectively and directly detecting a ventilation rate of air moving through the return damper apparatus and communicates the ventilation rate to the controller which selectively modulates operation of the heating unit in dependence upon the ventilation rate.