Anybody with knowledge of radon mitigating in-line fans.

If so, I have a "radonaway" fan that had a broken impeller which I replaced and am puzzled the way the blades are configured .

They are flat , radial and straight and appears to me that the air comes into a small central opening and is pushed out radially by centrifugal force.

So I suppose it would be called a centrifugal fan. Wondering if this configuration makes it quieter. What about efficiency which looks compromised to me since the air would strike normal to the enclosure, not a very good idea.

Thanks for listening