I'm posting the results of some comparisons I made on three fan assemblies.
I used a water u-tube manometer to measure suction and pressure from each; a digital phototach to check rpm; an Amprobe to check current.
1. NBK 12 blade paddle fan (new)
2. AO Smith squirrel cage 4-3/4" (used)
3. FASCO squirrel cage 4-3/4" (used)
I also swapped out the squirrel cage for a 4.44" 9 blade paddle on the AO Smith.
![[Hearth.com] Exhaust fan testing](https://www.hearth.com/talk/data/attachments/224/224738-36bd28aefce6bea6ab1de2272c230e33.jpg?hash=dp6mclsnke "[Hearth.com] Exhaust fan testing")
![[Hearth.com] Exhaust fan testing](https://www.hearth.com/talk/data/attachments/224/224739-0b512898aa0d944ee0b99c8c4c5de7af.jpg?hash=MoYms4-3zT "[Hearth.com] Exhaust fan testing")
![[Hearth.com] Exhaust fan testing](https://www.hearth.com/talk/data/attachments/224/224740-70d897eb548c717d91b5d6bc684abb0b.jpg?hash=6bkGkerRJc "[Hearth.com] Exhaust fan testing")
![[Hearth.com] Exhaust fan testing](https://www.hearth.com/talk/data/attachments/224/224742-715a6494f4c356e9805a654e7227efd0.jpg?hash=lBEaNxky_J "[Hearth.com] Exhaust fan testing")
![[Hearth.com] Exhaust fan testing](https://www.hearth.com/talk/data/attachments/224/224741-546928180717dbd9a3e59045754149ba.jpg?hash=nLUOVtgNw9 "[Hearth.com] Exhaust fan testing")
I used a water u-tube manometer to measure suction and pressure from each; a digital phototach to check rpm; an Amprobe to check current.
1. NBK 12 blade paddle fan (new)
2. AO Smith squirrel cage 4-3/4" (used)
3. FASCO squirrel cage 4-3/4" (used)
I also swapped out the squirrel cage for a 4.44" 9 blade paddle on the AO Smith.
