Comments about Best Best by Broan EB SeriesBrushed Aluminum External Blowers:

[...] the fan does not spin without scraping the duct flange below. Very, very noisy and probably shortens the life of the motor considerably.[...].But this also looks like it's partially a design flaw, since the fan is mounted to flimsy aluminum sheet - so when the wind blows or temperature shifts the fan collides with the duct flange.Unfortunately, not only is the Broan EB15 a poorly designed product, the Broan service is poor - we had two Broan servicepeople look at it and both could not figure it out. One accused the roofer and said that the roofer should repair it. (Huh?)The other was scared of climbing on roofs and would not look at it.Stay away.