So after my HVAC tech did my zoning system install, which I love, we started speaking about my soon to be new variable speed 2stage goodman/amana furnace and possible addition of return ducts. Right now he said my returns are "marginal" but placement is bad, 1 10x20 return in the upstairs hall, 1 10x20 return in the downstairs living room, and 1 8x8 return in the basement. The basement return is at head height and the upstairs/downstairs returns are at the floor. Anyways there is a deep closet in the living room and he said extending the basement return up the back of the closet into the attic and adding small 8" flex returns to each room would make "any" system better, he also said to eliminate the basement return or zone it so that it only opens when the basement zone calls (not yet added). He said the basement adds to much humidity in homes, even though this one is dry he said basements are just humidity prone.
1. Is it worth, $$ wise, putting small returns in each room? The upstairs is just over 500sqft, downstairs <500sqft, Kansas City area, 2.5ton AC, 90k 80% furnace (going to 95% 72k), energy audit shows the three upstairs bedrooms are high pressure (I'm guessing due to no returns with doors closed)
2. Would you do it?
3. If I do it, do the return ducts in the attic need to be insulated?
4. If I do it, the returns will be ceiling mounted...does this affect your decision?