I have a 100 year old house with a boiler almost as old. I will be doing a complete renovation includeing replaceing the heating system. I have baseboard hot water in about one third of the house. How do i design a central air system , includeing size, ducts, returns, and vent placements?
Size A/C needed: Rough estemate only: L X W X H X (6) div by 60 min div by 400 cfm= TONNAGE REQUIRED. The figure of (6) is air change per hour and is usually 5. Since your house is older I made it 6. Once you find you tonnage needed, Now youcan start sizing duct. There are charts for this.