Furnace Humidifier Water Always Running . I set the damper for 1/2 open in the winter or it brings in too much. Both conditions will stop the water flow to the humidifier and/or to the motor that turns the humidifier wheel. How To Install A WholeHouse Humidifier?My Finest Air from www.myfinestair.com Water keeps going through the soilniod valve and keeps running. Received 2 votes on 2 posts. See also will humidifier work.