Which would be \"better\"?

DIY Homeowner

Efficiency-wise, is it better to reduce the boiler water temperature, or use a night-time set-back?

System is in a 1000 sq.ft. circa 1957 ranch in western Mass, has 59 feet of cast iron baseboard on main floor, 16 feet in basement family room, oversized cast iron boiler with 87K output, main floor is monoflow distribution.

Right now the boiler aquastat is set at 180, and I use a 3 degree (68 to 65) setback at night. New insulation in the attic (was ~R-13, added R-25) has noticably reduced heatloss in house. I noticed that a larger setback (8 degrees) resulted in boiler short-cycling, but the 3 degree setback doesn't seem to cause any problems.

Thankx.