Joseph Meehan wrote:

Just not worth it...

Got physics? :-)

"---MIKE---" wrote in message
...
I have a small log home. The logs are efficient insulators plus they
act as a heat sink. My heat is baseboard hot water and I have two
thermostats controlled by a homemade switcher. The "day" thermostat is
set to 65° and the night one is 57°. This does save some oil. My
question is about daytime if I leave the house. Does it make sense to
go on the lower setting for just four hours? It would use less oil
during that time but then it would use more to "catch up" when I get
home. What would be the minimum number of hours that would give the
best savings on oil?

There's no minimum time. Turning the heat down always saves energy.

Nick