Is my furnace working correctly?

westend wrote:
I would think that before a user starts blocking vents or placing pillows over registers, it might be a good idea to inspect the plenum and ducts to make sure all is connected and in good shape.

X2 on being careful with vent blocking. I had a bedroom vent blowing too much air. I blocked 50% of it with a pillow. The heat "backed up" and warped the polystyrene material that the duct was made from. Now I have to replace the entire run to the bedroom.