When it's cold outside, your furnace and water heater work harder, accounting for 86 percent of the typical winter gas bill. There are steps you can take to reduce seasonal gas bills: First, for both safety and efficiency, have your furnace professionally inspected and perform routine maintenance. This includes changing filters. Second, if you haven't done so already, install a programmable thermostat to automatically control your home's temperature. Third, weather-strip and caulk all drafty windows and doors -- that'll save at least 5 percent on your heating cost. Fourth, check heating ducts for leaks, and make repairs with a mastic-type sealant (not duct tape). This could cut heating costs by 5 percent to 20 percent. Finally, lowering the setting on your water heater thermostat cuts water heating by 10 percent to 20 percent.