My old system used a 20 x 25 x 4 filter... I think that was the best available 15 years ago. My new ClimateMaster TEV049 unit has the slot for a 2" pleated filter and the air coil is about 28x30. It was installed with a nice large box on the return so I have good airflow across the entire coil... and old 20x25 filter feeding box from the top. So, I guess I have the option of using the 2" and just removing the 4" 20x25 if I want to... 20x25 = 500 sq in of filter at 4" pleat depth, as opposed to 840 sq in at 2" pleat depth. Any recommendations on which one will give me best filtration? Best air flow? Best all around combination of air flow and filtration?
I have always liked electronic air filters as they remove more dirt from the air stream and always restrict airflow less as they (except for the aluminum mesh pre-filter) are not interference-type filtration. A way to check to see if you have 'too much filter' is to accurately check the return air temperature and the supply air temperature when they unit is operating in cooling. Ideally the difference (if you live in a green grass climate) will be about 20º F. but whatever it is you want to check to see if the Difference changes if you remove the filters. A good time to make this check would be right before you are changing the filters - rather than when the air filters are new. CJ ------
