6" round to a rectangle duct?

[Kungur]

I am going to be installing an in-line exhaust fan. It is a Broan. It calls for a 6" round. But I need to go down a stud space then back to the 6" round. What size is correct for the stud space duct? Thanks, Tom

[HVAC HAWK]

most hd and Lowe's have What i think they call wall stack ?

this is a 2 piece duct that fits in side a 2x4 wall space and they have the fittings that goes from this size to 6" round .

hope this helps

[Kungur]

Thanks! I also did a calculation of the area of a 6" duct. PI x the radius squared.

[HVAC HAWK]

was this a bath or kitchen vent ?

either way you need to seal the joints . you can use foil tape that way the smell does not come out throw the joints .