I need to replace my bathroom ventilation fan. I am in 2nd floor condominium. My bathroom dimensions are 60 square feet and ceiling height is 8'2".
As per formula I found for CFM (height × length × width × 0.13) ,I need fan with around 62.4 CFM.
I can only find 50 and 80 CFM fans, can't find anything between. Should I go with 80 CFM fan ? There is around 10' to 12' of duct work before it opens outside on the wall.
I have attached picture of the flexible white duct which is connected to solid metal duct as you can see in the far end of the picture.
Can I replace flexible duct with solid duct to get more smooth air flow ?
Do I need to buy insulated duct ?
My building is around 34 years old. Not sure if there are specific code requirements for my case.
Best Answer
You can certainly go with an 80 cfm unit, the only drawback being additional noise (in general the more powerful the unit the louder they are). This can be remedied by using a high-quality unit designed to be quieter.
You certainly can (and should IMO) use regular duct pipe in lieu of flex, wherever you can.
I don't think you need insulated duct for this. I live and work in a temperate region and am unfamiliar with considerations for vents in unconditioned spaces that could drop below freezing, but the fact that the existing vent is not insulated is a hint that it should be fine.