Hey. I’m new to forum. I live in Nashville a have a craftsman style home built in the early 1940’s.
The HVAC duct that supplies the upstairs bedroom run through a bedroom downstairs and the size of the casing around it makes the the door only open half way. I have attached pictures. I want to switch the duct something rectangular and narrow and snug a duct against the wall so in can open up the door a reasonable Distance. I’m looking for some guidance as far as the parts go. I was thinking 4” x 12” rectangular duct would carry the load. I’d love to go smaller but....thank you for taking a look.