I recently got a new furnace method plus the brand new component started making a whistling sound. I thought that was how furnace devices operated until our sibling complained about it. She told me that a heating method making a noise meant something bad. Since the component was brand new, I was really angry at the thought of it already being messed up. I looked online plus found that a congested furnace filter could be the reason for the whistle noise. The reason the sound happens is that the airflow is being stopped in the system. The air filter could be the cause because if it gets super caked on with dust, no air can get to the system. So the furnace has to find a way to move air in a unusual location plus this causes a whistle. I took care of the Heating plus Air Conditioning filter plus it looked fine. Even though it seemed clean, I did buy a whole new 1 plus that did not fix the issue. I then looked into other possible concerns plus 1 was that there is a gap in the air duct. A small hole between the duct plus the furnace’s blower will cause a loud sound. I looked all around in our furnace method plus even had our sibling take a peak, every one of us could not find a gap. I finally called a Heating plus Air Conditioning girl into the house to see if every one of us missed something. The girl instantly said the issue was that our ducts were certainly too small for the furnace device. The furnace needs larger ducts for greater airflow. So that was an high-priced appointment.