I'm puchasing an older 2 story home in minneapolis {1926}. Right now it has an old boiler {1965} in the basement and no a.c. I'm looking for advice as how to upgrade the mechanicals. I'm considering putting a forced air unit in the attic where there is plenty of room. I figure this is the best way to approach it ,taking care of both my heating and cooling. There is an unfinished basement and a nice chase from the attic {stacked closets}. Are there any codes, cocerns I have to be aware of? I'm an electrican by trade but will be hiring this one out. All input is appreciated.