As an adjunct to another thread, let's walk thru the work/effort to convert a 2-story colonial with a gas/AC/forced-air unit in basement to support zoning to balance the temp diff between floors during cooling season.
Here's the ground rules:
No new ducts, supply or return.
No drywall rework
Basement has supply and return trunks with takeoffs to each register listed below.
Basement is finished but has suspended ceiling, so access to takeoffs and duct is good. Running low voltage wire back to furnace room in basement is doable.
Here's the parameters.
2nd floor, 4 bedrooms, 3@ 140sqft (1 register), 1@280sqft (2 registers)
2nd floor also has two baths, each with one register,
2nd floor return in hallway ceiling, centrally located and only one. Doors undercut and as a rule left open for circ.
1st floor,11 floor vents.
2 in family room
2 in kitchen
2 in dining
2 in living
1 in foyer
1 in half-bath
1 in laundry room
1st floor return in open-foyer

So let's start with basics:
(a) Which ducts get dampers?
(b) Where are dampers installed (at takeoff or at floor reg, or anywhere in between)?
(c) Assuming controller installed at furnace w/ no special power requirements.
(d) Where would temp sensors need to be installed and how many?