Lurking for years so thanks for all the great info!
In our master bathroom there is a small water closet that just has the toilet (about 6' x 3'). The WC and the tub area both have exhaust fans that are connected in the attic and then vent out the roof. The venting is done poorly with 3" flex duct that is buried in fiberglass and blown in insulation and has probably been banged around during other repairs (the entrance to the attic is above the door to the bathroom so any work done involves walking near there). The connection through the roof is also loose and needs to be fixed.
I want to redo the ducting, make sure the fans are sealed around the ceiling, and I will likely just replace both fans since they are 12+ years old and I'll be up there crawling around anyway.
Do I need a fan in the WC that vents out of the roof? This fan isn't expected to move moisture, just odors. We don't run this fan during showers, only when using the WC for maybe 5 minutes a day. If I do need a fan, is there any version that doesn't need to vent to the outside? Like one with charcoal filters or anything? I do like having the fan for odors and for masking sounds...
If I can remove that fan or the ducting between the two, it will be a much easier install and then I won't be worried about it being damaged when working up there. Thanks!
Inspected ducts in attic