I don’t use expensive filters. I use a simple pleated filter and change it every 30 days. When I get the electric bill that’s my signal to change the filter. I keep a box in the garage. I also keep a can of cheap furniture polish in the box as well. Before I replace the filter, I spray it with furniture polish. This helps attract and hold finer dust particles making a cheap filter better.
Today while browsing, I saw an interesting ad for system performance checks. Everyone always feels more is better, 44 ounce soda for a $1.oo is better than 12 ounce soda for $1.00. I see the same behaviors in air conditioning check ups and air conditioning tune ups. The real issue here is what’s checked before and after and what should a maintenance plan actually include? I can check 85 items, even 90 if I track every single step I take in inspecting and cleaning.