Zoning a 30 year old heat pump system

SteamingatMohawk

My 1988 vintage house has a York heat pump with gas backup HVAC system. It works fine and we haven't bothered to use the heat pump for heat, opting for the gas furnace. Without doing any cost calculations I assumed the gas cost is less than electricity and the unit is only good at or above 40F, so by this time of year it's not worthwhile.

We have no zoning and the lone thermostat is in the dining room. It's only my wife and me and we do "manual" zoning by shutting the registers in the unused bedrooms.

I have thought about zoning the house, but never got very far into the details. One of my sons has an Arzel pneumatic zoning system installed when he rehabbed his home.

Any suggestions?