Abstract: A flow through humidifier is disclosed having a water distribution tray disposed above an evaporator pad. A drip nozzle is connected with the outlet of a water supply tube and delivers discrete water drops to said water distribution tray. The drip nozzle may be located outside or inside the tray. A humidifier housing is connected with an inlet air duct which extends between a first furnace air duct and the housing and the housing outlet air duct connects with a second furnace air duct. An adjustable damperer is disposed in one of the humidifier housing air ducts for restricting air flow through the evaporator pad. In a second embodiment, water is supplied to the drip tray under control of a float valve which is actuated by a float posed in a water collection reservoir.