It has been about 3 months since I changed my air filter, so I recently purchased a new filter to replace the old one that was filthy. Typically, most HVAC providers recommend replacing the air filter every 90 days. And if you’re a smoker or if you have pets, the recommendation is between 30 to 60 days. I have always kept up with replacing my HVAC air filter as it is a sure way to guarantee that the air quality in my home is ideal. And each time I change the filter, I always make sure that I install it the right way. However, for some odd reason, when I went to replace the filter, I realized that I had it pointing in the wrong direction. If you don’t know anything about HVAC air filters, most if not all of them, have arrows showing you which direction to place the filter inside the HVAC unit. The arrows should always point towards the unit, but for some odd reason, the arrows on this filter were pointing the opposite way, which means that the filter was installed incorrectly. The only thing that I could think of is that, about a month ago, I removed the filter to take a picture of it, so that I could order the same one online. And I believe that in my rush to return to what I was doing, I didn’t check to see what direction I was installing the filter. So, for about a month, my air filter was installed backwards. This means that the air wasn’t flowing as it should nor was it getting filtered properly. To avoid this mistake, be sure to check the arrows on the HVAC air filter and never install it backwards.