Winter is the time that we use and depend on our furnaces the most. Proper maintenance schedules and replacement of filters can help extend the life of your furnace. Make sure to replace the furnace air filter monthly. A dirty filter keeps pet hair, dander, smoke, and allergens in the house. The filter picks up most of the debris and can get clogged especially when being ran constantly. If the filters are not change regularly they will begin to clog, restricting air flow, and making the furnace work even harder.