We have an old house that happens to have forced air. Unfortunately, according to an HVAC tech it looks like there aren't sufficient return vents to add a compressor to our furnace.
I guess I'm confused why the heating system itself doesn't need as many return vents -- seems like it wouldn't work without one? The tech identified just one return vent in the whole house -- on the ground floor.
What options are there for adding return vents to a smaller home (around 1500 sq ft over 3 floors)? Where can I put them without having to build out my walls and sacrifice space.