What is the most economic temperature to run your furnace when no one is at home?

If you are gone for days at a time set your thermostat at 40 to 45 degrees, unless you have pets or plants in the house, then set the temp at 50 to 55 degrees. However if you are only gone for a day (say at work) you may only want to set the thermostat at 50 degrees because the lower you set it the longer the house takes to warm up after you get home.

For daily occupied/unoccupied set the unocc 5-8 degrees lower than occ, for sleep mode setback occ to whatever is comfortable to you. For away days at a time I would go no lower than 55-60 to avoid the risks freezing pipes along exterior walls and basement.