I own a rental apartment with more than two units, every unit has their own Heating and Air Conditioning unit and unluckyly, the renters are absolutely exhausting about air filter changes… For a while I was consistently getting phone calls about the Heating and Air Conditioning making noise, being inefficient or just not getting the task done. I realized that jammed air filters were the cause of all their concerns. I told every a single of my renters that once a month they need to change out their Heating and Air Conditioning filter. I even provided to pay for the filters so that I could ensure they would do it. Nope, that didn’t help at all. It seemed care about I was coming to my rental apartment every month anyway on Heating and Air Conditioning filter changes. So what I have now been doing is on the first of every month changing the apartment air filters. Since I have more than two units though, I have more than two odd filters to change. Not only do I have to coordinate with odd renters and find a time that works for everyone, but each air filter is different. I never remember what size, brand and genre to get once I am at the store. I wish there was a a single size fits all air filter or an insert that expands to make a filter fit in the system. Typically I end up buying tons of air filters and trying them in each system. The leftover a singles I then return. I absolutely need to schedule the right air filters being shipped to my lake house or remember what each rental unit’s air filter looks like. No matter what though, the a/c filter issue is super frustrating.