J.Albert wrote: "should mention that my system isn't "steam".
It's a gas furnace/boiler, hot water, cast iron radiators.
2-story house built in 1911, no insulation, plaster walls,
original windows. "

My Gods Jim! Tighten up that draft stack
you reside in: Insulate at least the attic,
repair any cracks in the plaster walls and
ceiling, and weatherstrip all exterior doors.

Then you can have your +- 2.25 degree temp
swing using less of our precious resources.