Yes, I meant to say humidifier. I have a Carrier furnace with a Carrier humidifier attached to the right hand side of the airhandler duct on top of the furnace. There is a flexible aluminium duct that runs from it and goes to the bottom of the furnace to the blower motor. The aluminium duct heats up quite a bit and I think it is a radiant loss of heat and am planning to shut it off. Yes, I will make sure to shut off the water line too.