My house was built in 1975. I have a subfloor with ample crawlspace. We reside in south Georgia. Currently my AC ductwork is under the house which is in desperate need of replacing. I have a vaulted ceiling in my living room which does not enable me to run duct work through the ceiling to the 2 adjoining rooms on that end of the house. With all that being said, I was wanting to know which would be more benificial? Ductwork running through the ceiling or putting it back in the floor. I am willing to put a mini split on the end to cool the 2 rooms. The bottom line is I need more air to my living room because of the high ceilings, which in turn holds hot air at the top.
Personally, I'd keep it in the floor as you have access to the whole house in your crawlspace. Even if I could get ductwork to the other side through the attic, the crawl is still my preference, especially since you have registers already cut into the floor.