"Noon-Air" wrote in message
news

"BillC" wrote in message
link.net...
HI,

I set the thermostat timer for a minimum overnight temperature of 45
degrees, to heat to 70 at 6:30 AM. Effectively, this leaves the furnace
turned off overnight. I figure that saves wear on the furnace / fan and
saves fuel costs overnight.
However, I heard on a radio program that thermostat timers should
only have a max differential of about 8 or 10 degrees.

Anybody know what the best settings are?

use 10 degree setbacks for best efficiency and least problems

OK, but why? Does 15 or 20 plus degrees of heat differential mean the
furnace gets too hot when running to close the gap, or what?