ASHRAE Standard 62.1 suggests maintaining a
relative humidity of no less than 30 percent to provide a comfortable, healthy
indoor environment. Trane humidifier modules use low-pressure steam distributors
to add moisture to the air. They include accessories such as valves, strainers,
and traps. Factory mounting within the air handler lowers the installed cost of
the humidifier and keeps moisture out of the supply duct.