Zoned System

Does anyone have a good explanation or definition of a zoned ac system? I’m looking for something that explains a zoned system and easy for the homeowner to understand.

This has good info:

What I have seen in residential areas is pretty simple. If there are 3 thermostats then there are 3 dampers in the supply ducts to each zone. There is also one bypass. All 3 dampers are in the fail open mode. If one thermostat is calling and the other two are not, then the two that are not calling close. If your client has a home office that he wants cooler during the day while the wife and kids are gone he can just cool the office area with out cooling the rest of the house. It works well but the builders try to cut back on the tonnage or btu rating of the unit to save a buck. When they do that it may not work well on a high demand day.

I have two 4-zone Carrier systems in my home which were installed in the early 1990s and have worked well since (I did have to replace 1 damper). Carrier is likely to have some literature.

In wording that most homeowners can understand, it is dampers in the duct work that direct airflow to the area(zone) that needs it to satisfy the thermostat setting for that area(zone)

If they are worried about the size of the system being adequate, have a HERS rater run load calculations to size equipment. The HVAC contractor can do that also, but as a HERS Rater, I don’t make any more money wheteher it is the correct size or needs to be replaced.