Think about running the heat tonight

[MarkB]

you shouldn't set back more than 4* you will not save a dime as an example.

Where in the world did you get that idea? Sorry dude, but you're makin' it up and giving very bad advice. The physics of this question is very simple - turn down more, save more fuel. There's no magic 'wicking' to take account of. This is a very simple formula:

1. The more degrees you keep your house above outside temps...

2. for the longer time

the more energy you use.

If you either set your thermostat lower, or keep it lower longer, you will save fuel.

And running the furnace to raise the temperature more than five degrees doesn't hurt the furnace. A furnace is not like a car engine - it's not like you're pulling a load up hill. The furnace always runs at the same rate. To raise the temperature of your house more, it just runs longer. If anything will hurt your furnace, it's cycling on and off, not running for a long time. That's true of any machinery - it's always the cycling that does the damage not the standard running.