Abby Normal wrote

come back and see me when you figured out how to
get multiple systems to share common duct work rookie.

Dont have to share the same ductwork, ****wit.

Dont even need any ductwork at all with the system
that is used to come off setback at a decent rate.

Dont even need multiple systems either if you're happy
to come off setback for the evenings and use passive
solar assist to come off setback earlier in the day.

Keep desperately digging, you'll be out in china any day now.