Just had an Aprilaire 700 humidifier installed on the supply side of the furnace (trane, 1200cfm when blowing for A/C), and the darn thing is whistling like a teakettle! Huge air flow coming out of the small vent slots on the front of the humidifier. So...

1) Is it supposed to do that?

2) What are those vent slots for? I suspect they are for cooling the humidifier motor.

3) How do I make it stop? If the slots are for cooling the motor, I should be able to seal off the motor area from the main duct airflow and stop the air leak into this area.

I do have an HVAC pro, but I want some options before I get him re-involved.