i have a 1400 sq ft house, im installing a 60,000 btu furnace a 2 1/2 ton condensor. all the walls r tore out and r being well insulated, i have a total of 11 supplies and 3 lower returns in bedrooms prolly 6 x 10 x 7" flex that will pull a joist pocket and 1 big 14" flex bag for the living room and rest of the area its a open concept. 5 supplies r under 12 ' from trunk line over the windows and doors 6 r about 20' from trunk line totaling about 180 ' insulated flex total.
I was thinking of running about 20' of duct work for the supplies it is a horizontal in a attic, i was thinking of 8x20 ,8x16, or maybe 8x16 and 8x14, return cfm is only 1200 ,,,,does any 1 think this is the way to do it...am i on the rite track.......does anyone have any advice on the supply trunk size .
or is this rite ...all advice will be greatly appreciated thanks.