My current residence is a 1000sf 1 story ranch home, which is heated with a forced hot air oil furnace. We are planning on adding a second story, essentially doubling the square footage. The second floor will be 3 beds and 2 baths, and the existing first floor will have most of the existing bedroom walls removed to be a mostly open floor plan. We live on the MA/NH border so have cold winters and hot/humid summers.
I was originally thinking that I would extend the duct work up to the second floor to serve my heating needs, but then started learning about heat pumps. It seems to me that this would be a great choice for me. My plan would be to leave the oil furnace for heating the lower level, and adding the heat pump for heating the second floor (I am thinking that it may not even kick on that often depending on how much of the heat from the first floor makes its way to the 2nd.) Am I on tract here or does somebody have another idea.
If I am on track here, I had one other question about the heat pump. I would think this unit would be most effectively installed in the attic, from where I would duct into the new second floor bedroom ceilings. Currently the house does not have AC, but now would be the logical time to change that. I am thinking I can run ducts down from the attic to vents in the first floor ceiling. How would this impact the sizing for the unit, seeing that I would only be trying to heat the upper floor but trying to cool the entire house?