How To Place Duct In Window

[saltwater]

I live in Oregon so it's starting to get cold and I need a way to seal off my window and only leave my 4" duct.

My window shuts going left to right. It's about 5 ft high. I was think about getting a piece of wood and cutting a 4" hole and then placing the duct in there. But idk. Anyone have suggestions ?

 

[DrFever]

think about it first get some plywood measure inside dia of window frame cut plywood then cut a 3.5 " hole push ducting into the inside of hole like 3" use snips cut slots 4 of them fold over ducting staple n tape ,,,,,
now get mylar use the black side facing outwards press it behind window your done remember to open window prior ...
And remember black part of mylar stapled out wards so if someone walks by and looks at window all they see is black

 

[Seamaiden]

I'd just add a bit of sheet Styro to that plywood thing, so you've got some insulation.