bathroom fan venting

I am replacing an old noisy bathroom exhaust fan that currently has a 4" roof jack/cap and 4" ductwork. According to the proper calculations, I would need a new exhaust fan rated at 190 CFM. However, I can't find any 4" exhaust fans with CFM ratings this high. The roof is 7/12 pitch and I...

I had this post in HVAC for theee days. Got 89 views, but no response so I decided to repost it here. Venting a first floor bathroom fanWhen our house was built no bathroom fans were installed. Now, I have a few questions before beginning this project. 1. I can run the duct work between...