Just figured something out with the Heat Pro and I'm wondering if I'm the only person to have it come up. From day 1, the fan motor has worked just fine, but was noisy on the lowest speed. (where it spends 90% of the time...) By noisy, think when an electric motor is just turned on, and in makes kind of a whine until it gets up to speed, and then goes to a quiet hum. In my case, the whine never goes away. Squirrel cage mounts directly to the motor. No belts, extra bearings ect. to cause any issues. Funny thing was, it suddenly started to get better. I noticed the filters were getting dirty, and the second i slid off the dirty filter ... the whine came back! I set my filter box up with 2 filters, 1 on each side for a non-restrictive path, and may have inadvertently cause a higher load on my blower motor, by actually moving more air. I'm going to borrow an amp clamp to see exactly what my loading is ... but just thought I'd ask if anyone else ran into this issue?