Thank you for the response. There are two ways of creating multiple zones.
One is to have a single HVAC system but use dampers to heat/cool different
parts of a house differently. The other is to have completely separate
systems (they can use the same fuel or different fuel). It makes sense that
a thermostat with remote sensors would work with the former but not the
latter.
That is my problem with these smart thermostats. I would need to buy 2 of
them. It would take a long time to save enough on power to pay them off. I
just try to keep my house as warm as I can stand in the summer and as cold
as I can stand in the winter.