Furnaces come in all shapes and sizes, however the filters are easily replaced if you follow these simple instructions:

1. Turn off the furnace fan.
2. Remove the new filter from its plastic wrap. 
3. Locate the arrow on the side of the filter. This arrow indicates the side of the filter that faces the furnace 
4. Insert the filter with the arrow pointing towards the furnace fan.

Check your filter package to see your particular filter's intended lifespan. Typically, more expensive filters are designed to last up to 90 days, whereas less expensive filters are generally designed to last up to 30 days. Your filter's lifespan will greatly depend on the conditions of your environment however, so to help ensure your system is running optimally it is recommended that the filter is checked frequently and replaced earlier if necessary.