Have HVAC Questions? Ask an HVAC Expert for Answers
Have you tried removing the jumper? That could be causing it to bypass the thermidistat.
I would almost bet its a wiring problem with the t-stat. Let me look into it.
I would try D1 for sure. That may stand for dehumidifier 1 , As you stated you have 24v at Hum terminal on the tstat when it is calling for the humidifier and when you turn the setting down the 24v goes away as it should. That part is correct. Let me see if i can get a wiring diagram for that unit.
Do you have the Optional airflow switch installed?
Can you send me a picture of your tstat terminals to***@******.*** That would help a lot. We will get this fixed one way or the other.
Did you ever try D1? Try putting the other HUM wire on C . Not G.