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pleated 5 inch filters

Paul_69 Member Posts: 251
are the 4-5 inch filters to restrictive to add to existing duct systems on residential furnaces? will the air flow suffer? i have never installed one and have had conflicting views. some say just stay with standard 1 inch unless you design the system to handle the thicker filter.also if you cant move supply duct or return duct at all could you move furnace over 5 inches  and offset supply plenum transitioning over 5" so you would have space between return duct and furnace return opening so you could fit filter unit?would offsetting the supply affect airflow? has anyone ever run into this senario?i hope this makes some sense!


  • SWEI
    SWEI Member Posts: 7,356
    Look at the numbers

    The deeper the pleats, the lower the air resistance.  I've squeezed a number of 2" ME filters into residential and light commercial systems over the years with good results.
  • John Mills_5
    John Mills_5 Member Posts: 935
    Low restriction

    Usually the 5" are much less restrictive than the 1" pleated filters. To me, the 1" pleated are the worst thing invented for HVAC.

    Take our office. With the VS blower set to 1600 CFM, I measured static drop over a dirty Aprilaire 213 media. I read .29" drop. The clean media was .23" drop. Clean Honeywell and Trion medias were in the .25 to .30 range. Generic version made by Indigo was more restrictive.

    Then I put a 20x25x1. Clean, the drop was .5". Ouch, consider that the TESP for a residential system should be .5" with ducts, coil and filter.

    So a good 5" media cleaner with OEM media will be a good way to go. We encourage them on every replacement job.
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