We all agree that the heating system should remain on if you are going away for a period of time this winter. The next thing to determine is what that 'decreased temperature' is to set the furnace at in order to keep your home safe. Be careful of how low you set that furnace to run at; you shouldn't just be thinking about your pipes. Consider the amount of time you will be away, and the work that your system will have to do in order to reach that normal heating temperature again after you've returned. Experts don't recommend dropping the thermostat down much more than 5-8 degrees or so in the winter time. A furnace that is trying to recoup a larger temperature swing can be overworked, which can lead to furnace issues, both instantly upon your return and in the future. The money saved by drastically lowering your home temperature for a period of time is not likely to amount to much in comparison to the cost that the additional strain put on your system may be.