I'm looking for advice on which size of trunk & ducts to use. I've used a ductwork calculator that is associated with Menards and they drew up a plan but it doesn't take into account some things that I need. I have a 1 story house with a basement. The furnace is in the basement. I marked on the floor plan where registers need to be. The kitchen is open to the living room. I marked where I want the registers with "R" and cold air returns with "C." The house didn't have central air before so there are no holes cut in the floor which gives me some flexibility.
On the basement floor plan, I placed the furnace and plan to run the main supply trunk to the west. I'll also need something to go east since I'll have the Office Register and the Kitchen Register. (I want to go east/west with the trunk because the floor joists run north/south and that will allow me to tuck the runs into the gaps between joists which will save a ton of headroom and allow us to use the basement area south of the dotted line.)
I have a 60,000 BTU furnace and 2.5 ton AC unit (haven't installed that yet).
I will have a total of 7 upstairs registers. I drew up a plan for 4 basement registers. As you can see the fireplace and stairway block where the main trunk would extend to.
The Menards drawing said to use 8in round ducts for most of it, not sure if that's necessary but a friend of mine (that worked with heating a cooling previously) said maybe that's because there are not very many registers in the house and the furnace needs to move a certain amount of air???
What size of trunk do I need to use and when should it be reduced down?
I believe I have the cold air return's figured out because when the furnace was installed, it came with a cold air supply so I figure as long as I bring in at least that much air, it'll be good.
THANK YOU FOR ANY ADVICE!