The General 40 humidifier is a wholehouse bypass style humidifier designed for residential and light commercial applications. It can be mounted on either the supply or return duct system. It comes with a humidistat and will add the appropriate amount of humidity to your home to reduce static electricity, improve your breathing and comfort as well as protect your furniture and wood floors from drying out and cracking. Annual maintenance on the General 40 humidifier consists of replacing the humidifier filter or pad and washing out the humidifier.