Results 1 to 10 of 10
  1. #1
    Join Date
    Jul 2018
    Posts
    3
    Post Likes

    Filter Change By Final Resistance Rating

    Hey All, first time user here. In some of our filter banks we are using 3M merv a8 mini pleat filters w/ gasket FRR rating of 1.4" and I am wondering if there is also a max amount of time the filters should be used and changed out even if they have not met their final resistance yet. Any info on this or related subject is welcome. Thanks.

  2. #2
    Join Date
    Apr 2003
    Location
    St. Louis
    Posts
    639
    Post Likes
    merv 8 filters are good for 3 microns and larger particles, mold and dust mites. Are you using this filter for dust and mold or just dust. Changing at 1.0" across filter is standard but at a minimum if your looking for mold quarterly , dust twice a year and look at them quarterly in case a filter comes out of it's frame.

  3. #3
    Join Date
    Jul 2018
    Posts
    3
    Post Likes
    Thread Starter
    Using for dust only. THese filters have been in for a year or more against my judgment. They have not yet reached 1.4" and management wants to let them go indefinitely until 1.4" is reached. The main reason for my question was to get some info on why semi annually is the standard even they have not reached their final resistance rating.

  4. #4
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
    18,189
    Post Likes
    The same reason shampoo bottles say rinse and repeat.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

  5. Likes JeffWil liked this post
  6. #5
    Join Date
    Nov 2011
    Location
    East Side
    Posts
    4,892
    Post Likes
    All filters aren't equal. some are VERY expensive....some are inexpensive.

    with high dollar filters (bags, box, hepa, etc.) you want to get full use before changes....especially in critical applications.....hospital O.R. ahu's, chemical exhaust hoods, clean rooms, etc.


    In those cases, it's best to wait until the filter has reached its' life expectancy....the way to know that is to refer to the manufacturer's specs on pressure drop, and recommended frequency of change. I've seen manufacturer filter change recommendations that state as much as 5 years of use in some cases.


    now, if you have an inexpensive filter.....2-4" pleated, roll media, etc. It's best to simply establish a schedule depending on how frequently they get dirty, or just a time based change......once or twice a year, etc.

  7. #6
    Join Date
    Apr 2003
    Location
    St. Louis
    Posts
    639
    Post Likes
    I've seen alot of bag filters that have failed that have been left in to long and torn open not from being to dirty but the bag wears out by flapping in the air stream. With bag or hi efficiency pleats most use a prefilter that catches most of the big dirt so building managers want to leave them in to long except if it's a leeds building.

  8. #7
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    709
    Post Likes
    The filter material will break down over time. It can get small tares or holes, which will lower the differential pressure. The cardboard frames also break down and allow air to bypass the filters.

  9. #8
    Join Date
    Jul 2018
    Location
    Ohio
    Posts
    332
    Post Likes
    Not to mention the correct sizing for proper air filtration is 2 cfm per one square inch of filter surface area. I have gone round and round with manufacture's on this as they lay claim to 1" filtration, I challenge them to show me where a 1" pleated filter does not exceed thier maximum TSP requirements while actually filtering the air, their answer is a poly filter which we all know won't filter much.
    Why would you ever want 1.4" of static on a residential unit? Not one piece of equipment is rated to run like that!

    Well... except stuff like spacepac

    Sent from my XT1710-02 using Tapatalk

  10. #9
    Join Date
    Aug 2003
    Location
    Western, NY
    Posts
    827
    Post Likes
    Depends on what the A/h's serve. Being a medical center, we change ours quarterly. More often in the spring with pollen

  11. #10
    Join Date
    Aug 2006
    Posts
    3,119
    Post Likes
    Since I started working semi-stationary, I don't thing I've ever seen a filter last till it get to it's rated end pressure drop. Cardboard frames fall apart, buckle, grow mold. or start to leak dirt through the media. Sounds like my work where "Bean Counters" want to tell me how to do my job. BTW they had us recently switch suppliers, and the white brand begins with a "K" pleated filters are garbage.
    Retired, after 43 Years

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Related Forums

Plumbing Talks | Contractor MagazineThe place where Electrical professionals meet.