It can be beneficial to your furnace’s health to turn down your thermostat when you are away from home for extended periods of time. This can also save you money as well. Keep in mind though, if you’re only going to be gone for a short period of time, do not change the thermostat as your furnace will then have to work twice as hard to get back to your preferred temperature. Adjusting your furnace by just a few degrees is always better than drastic temperature changes.