Adding a ceiling register
My upstairs mancave gets awfully warm in the summer and I'm wanting to run a new register to help with cooling. The room is rectangular, something like a shoebox. One end cools just fine but the other end where my couch is doesnt cool so well. There is a register down at the couch end that doesnt cool well as the airflow is anemic. There is nothing wrong with the duct or any of the mechanics, it's just a long run.
I am moving an existing duct which was fairly needless because of its proximity to a return I added.
My question is; is it a problem to add a register in the ceiling about 6' directly across from the anemic register? Keeping the shoebox in mind the setup I had in mind was 2 ducts/registers at the end that is not cooling well directly across from each other with about 6' between. Is this O.K.?