A centrifugal blower having a fan including a blade. A scroll casing houses the fan and has a first axial wall portion, a second axial wall portion, and a side wall extending between the first and second axial wall portions. The scroll casing includes a suction port in the first axial wall portion. The scroll casing also defines a scroll start portion and a scroll finish portion. The scroll casing has a scroll radius measured transverse to the rotation axis that changes from the scroll start portion to the scroll finish portion. Also, a maximum radius of the scroll radius is closer to the second axial wall portion than the first axial wall portion.