WorthFlorida
Clinical Trail on a Cancer Drug Started 1/31/24. ☹
I prefer Merv-8 as a minimum yet I recently went to Merv-13 because of the pandemic. I'll probably go back to Merv 8 when I'm done with my 13's because the cost gets really high. My need changing every 90 days but for MD maybe every six months. I also added a UV light inside the air handler but it has nothing to do with dust.
Over the years the ductwork can get a lining of dust, the fan blower and the AC coils especially if the filters were not maintained. The other items I mention are all maintenance stuff. The blowers are a squirrel cage, some call then drum type. Each fin has a curve and inside this curve dust can accumulate to where it is less effective in moving air. Sometimes just scrapping a screwdriver in the grove and with a vacuum cleaner will suffice. The AC coils are the same as where they catch and hold dust, just like the outside refrigerator coils that are at the bottom of the refrigerator.
You don't have to perform any of this, just that you seem to want to know what's going on and what I see from the pictures. Of course you have no idea how the system was maintained by the previous owner but when you see filter hacks like you had it makes a good case. If the previous owner(s) had dogs or cats, it'll be always bad.
There are duct cleaning companies that do a pretty good job on cleaning. It's not a DIY type of job since it takes a big vac and cleaning brushes. To get an idea lift up some the registers and peep inside the duct work. You know of they are dirty.
As I said before if your not comfortable with this hire someone, have a work buddy or family member that has the know how. As with any homeowner, you'll need to budget in some maintenance every few years. AC maybe every five or more years.
Google "cleaning ac coils inside house" and "outside"
Drum fan cleaning
Over the years the ductwork can get a lining of dust, the fan blower and the AC coils especially if the filters were not maintained. The other items I mention are all maintenance stuff. The blowers are a squirrel cage, some call then drum type. Each fin has a curve and inside this curve dust can accumulate to where it is less effective in moving air. Sometimes just scrapping a screwdriver in the grove and with a vacuum cleaner will suffice. The AC coils are the same as where they catch and hold dust, just like the outside refrigerator coils that are at the bottom of the refrigerator.
You don't have to perform any of this, just that you seem to want to know what's going on and what I see from the pictures. Of course you have no idea how the system was maintained by the previous owner but when you see filter hacks like you had it makes a good case. If the previous owner(s) had dogs or cats, it'll be always bad.
There are duct cleaning companies that do a pretty good job on cleaning. It's not a DIY type of job since it takes a big vac and cleaning brushes. To get an idea lift up some the registers and peep inside the duct work. You know of they are dirty.
As I said before if your not comfortable with this hire someone, have a work buddy or family member that has the know how. As with any homeowner, you'll need to budget in some maintenance every few years. AC maybe every five or more years.
Google "cleaning ac coils inside house" and "outside"
Drum fan cleaning