Stumped Moron posted for all of us....

As a heating and AC guy, I've installed more than several Aprilaire
humidifier. Sounds like you've got a bad humidistat. Yes, it's supposed to
be in the cold return side. Yes, some of them have a sensor that goes
outdoors.

Yes, replace the humidistat.


I guess i will leave this alone because nobody can get hurt or killed by
taking his advice; however wrong it may be...
--
Tekkie