Since I've been in my house for a year now, I've noticed that I've got poor airflow in many of my rooms. I am currently working on sealing the ducts with mastic, but I also suspect that the previous owner added too many branch lines to the supply duct. For example, the supply duct for 3 of my bedrooms was also tapped (at a later point, I can tell, by the more shiny sheet metal) for 2 other branches in the basement. There is also an additional branch of that duct feeding into a basement bathroom.
The branch line that feeds the 3 bedrooms and basement is only 9 inches wide, and based on some reading, that appears to be undersized. I have barely any airflow into the 3 bedrooms. I decided to remove one of the branches feeding the basement (it just dumps air into the laundry room, but the laundry room is open to the rest of the basement, so it is unnecessary) and I was able to remove the 6 inch round duct from the starting collar, but for the life of me I can't get the collar off the trunk. I've tried reaching in and pulling up any tabs that I feel, but it's still stuck. What else could I do? Go after it with a pair of tin snips?
The one thing that I did notice is that when I pulled off the branch, that there was some serious airflow coming from the trunk. So I think the main branch has good flow, but it's just not making it to the bedrooms. Each of the bedrooms has a branch line that's probably over 10 feet long and fed into a wall boot, so I'm wondering if that's the problem. Maybe I should shorten the bedroom branches by adding floor registers that are closer to the trunk. Any thoughts?
