Bathroom fan: have 4 inch duct, want a 6 inch and more powerful fan

[slindenkohl]

If my current fan vents to a flat roof and is a 4 inch duct, what are my options for installing a more powerful fan - at least 150 CFMs. How hard is it to replace the entire duct? Do I need to or can I use an adapter? I have a large bathroom with a double shower, at least 150 sq. feet.

 

[WorthFlorida]

One problem is do you have access above the ceiling to make the change? You can use a flex duct which will make it easy to do. You're not in a cold climate so condensation would not be an issue. The real issue is the size of the current exhaust vent/hood. If it is for a 4", it can cause some restriction. Changing it up to 6" exhaust hood may require some work on the roof to properly seal it and allow rain water to drain away.

 

[Sponsor]

 

[Jeff H Young]

Its easy to replace the entire system as long as you have access . of cource every job is differant . the flat roof makes it easy to go on roof safely assuming you have a large attic to work in that will make it easy as well

 

[slindenkohl]

Thank you. The fan is above the toilet and it just exhausts a couple of feet up on the roof. Sounds like I can't just switch to a 6 inch duct easily.