Furnaces are new to us, turns out you need to change the filters in them… yup, shocking huh? Well we had our first cold night recently and tried to turn the heat on only to have nothing happen. Next day O'neil plumbing was able to come take a look at it and diagnosed a loose connection on a relay, no big deal. While here they pulled the filter door open to show us how to change them, then they gave us one of those looks that people give you when they think you are a terrible terrible negligent human being.
So this is actually the cleaner of the two filters. Needless to say we went to Home Depot that night and got nice high quality replacements. So listen up people, change your filters once every six months and if you are doing construction like we are, change them every three months; you don't want to make life harder for your furnace or your lungs!