Hi Guys I have a steam in duct humidifier with 55deg air discharge from my rooftop air handler.The humidifier has a wall humidistat in space also I have a transmitter and air flow switch in line going to my humidifier valve.

All my controls are functioning properly I've cycled it many times.The next day I got a call that the duct was leaking water. Does any one know what could be causing this I would appreciate any feedback and thank you in advance.

The discharge air temperature is not hot enough to keep the moisture provided by the humidifier in suspension so it condenses on the duct and falls out on the duct which causes water accumulation.

OR

The steamer is providing more moisture than the system can handle.

OR

The humidity level controls are allowing the steamer to run when it should not.

OR

The steamer has a supply water leak.

Without actually being there it is all a guessing game from here but the above are just a few ideas you might check into.