That leaves me confused because previously you said the humidifier was
plugged into a 120V outlet on the furnace. * The Aprilaire's I'm
familiar with that require 120V use powered fans and mount on the hot
side. * *The bypass models do not use 120V and mount on the return.

In my first post( 4th one down) I never metioned 120V on my unit. Are
you referring to the OP?