I had a new furnace and a/c installed and at the same time additional ductwork to a new addition. The new ductwork is 2 6" supplies and 1 8" return. The airflow is almost non existent so I need to do something. I looked into Fantech fans which look like high quality but even so the consensus here seems to be they don't work. Fixing the duct work with bigger runs is NOT an option as space is extremely limited. The system was sized with this addition in mind (about 20% of total house) so there should be plenty of airflow available. Do these fans really not work or is it just another Goodman scenario where some people just don't like them?
My other choice is a mini split which sounds like it will work well but obviously a lot more money in addition to the thousands I just spent on the new equipment. If I do go this route will the return and low flowing supplies effect the performance of the mini split? Do I need to close them off to keep the room sealed and separate?