Before you move your filter, you want to make sure and note the direction of air flow. It should be indicated by an arrow on the filter. You are going to want to make sure and remember this for installing your new filter. After that you want to inspect your furnace filter. Now it shouldn’t be very dark like this one is.

This is one is pretty dirty. Your’s should have a nice clean look. If it was originally white and it still is white, it is very good. Again, this filter is pretty dirty. Before you go out and buy a new filter, you need to make note of the size of the filter that you have.

You are going to want to buy one the exact same size I purchased this new filter of the same size. In addition, there are lots of different variations you can get with filters depending if you want to filter out allergens or anything else. When you install it, you want to make sure that air flow indicator is pointed in the correct direction and install your new filter just in the reverse as you took the old one out.