Our 2-story 3600sf home has only one zone, with a twenty-year old 5-ton HVAC system. We have the classic problems with a single-zone house -- the second floor is always 10 degrees hotter/cooler than the first floor.
We're thinking of converting to two zones, but the additional cost is daunting. A number of contractors have suggested that a variable speed furnace (such as the Trane XV90) might help reduce the need for two zones by continuously moving air through the house.
I would love for this to be the case, but am unsure. Does this strike you as a good approach?
Thank you for your thoughts.