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Thread: HVAC Air Filter

  1. #1
    Join Date
    May 2005
    Location
    Decatur, Alabama
    Posts
    5
    I have a Heil split system that may need a new 24" x 30" x 1" air filter and I don't know which one to select. For 4 years I used a series of inexpensive fiberglass filters and pitched them monthly. Last summer I purchased an expensive permanent washable A+2000 air filter that was guaranteed for life. I was washed monthly and I thought was working.

    Yesterday, my annual maintenence contractor came by to inspect the system. After doing whatever he does, he asked what kind of filter I was using. I told him it was the A+2000 permanent washable. He said to get rid of it as it was doing a poor job of filtering and there was a build up of fine materials on the inside of the ductwork. He said this could shorten the life of my circulation system and could provide fuel for a duct fire. He recommended use of a good quality pleated filter.

    What I want to do is THE RIGHT THING. I don't mind spending a bit more money every month on filters. That's a lot less cost than a fire or repair of the ventilation equipment. What is the right thing to do for both good filtration and reasonable control of cost? Thank you.

  2. #2
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    Pleated filters ,like 3M,are often very restrictive ,which can cause serious air flow problems.

    The contractor should test the static pressure,of the duct system ,be fore recommending a filter.

    24X30 sounds like a filter that fits in the return grille,if so uour a2000,may be very retrictive,and causing any leaks in the return duct,to leak much more,thus he say stuff ,that was never filtered.

    Tell us more about the system and ducts,model numbers ,etc..

  3. #3
    Join Date
    May 2005
    Location
    Decatur, Alabama
    Posts
    5
    Yes, this is an air return type filter. I think that the technician that worked on my system felt that the filter I am using (A+2000 by Filtration Manufacturing Inc. in Andalusia, AL.) is too open to retain fine materials. Those fine materials are apparently entering the duct system and collecting somewhere. The manufacturer specs. indicate that the filter is made up of "4 stage loading design/peak and valley webbing". "Contains no foam to clog or deteriorate". "100% washable". "Never needs replacing". "Maintanence - simply back flush with water or vacuum clean". "Removes particles as fine as 0.6 microns". The brochure recommends monthly cleaning and I have noted a lot of dirty water coming out of the filter when back flushed.

  4. #4
    Many manufacturers have a built in filter rack that houses a washable filter.
    It should be used to supplement the filter you replace monthly.
    In your case, I would suggest a pleated or standard filter and I would replace it monthly, regardless of what it looks like in addition to a washable filter to be replaced by the tech that services your system bi-annualy.

    Generally a washable filter is good for about 6 months before it needs to be removed, washed and reinstalled.

    The pleated filter is a device that causes a minimal pressure loss, no different from a standard filter.
    DPL of .03 for both types.

  5. #5
    Join Date
    May 2005
    Location
    Decatur, Alabama
    Posts
    5
    Thanks to both of you for your advice and comments. I believe I know what to do now.

  6. #6
    Join Date
    Oct 2004
    Location
    Texas
    Posts
    1,174
    Look into the aprilaire filter. I have a model 2400 and only need to change it once every 2 years.
    Saddle Up!

  7. #7
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    The type filter you have ,is likely a much greater pressure drop then .03,as even standard filters are usually greater,and of course the number is for a clean one.

    Having two filters increases the presuure drop,I wouldn't recommend it.

    I'd say wash
    it at least every month,if you see very little dirt,maybe two months.

    The pressure drop of the filter is in relation to it's size and the cfm(airflow)of the system,so can't tell from here.

    When filters are at the grilles the static in the return duct increases,so any leaks become greater,likely what's happening in your case.

    3M and other 1" pleated filters are known to be a problem,high pressure drop.

    What did you decide to do?

  8. #8
    Join Date
    Apr 2004
    Posts
    7,680
    I agree with Dash.

    As an added point, the reason you are having so much dust is because the filter is so restrictive the path of least resistance is leakage if it is not sealed. This can mean around the filter in its slot or through small leaks in the return duct system as someone else alredy pointed out.

    .03 is low. A standard fiberglass filter runs about .08 clean. Paul Har** filters are probably closer to .3

  9. #9
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    I also do not recommend having two filters.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  10. #10
    Join Date
    May 2005
    Location
    Decatur, Alabama
    Posts
    5
    After considering all the good comments, here's what I think happened with my A+2000 permanent washable filter situation.

    1. It was doing a good filtering job, but I was not doing a frequent enough or thorough enough cleaning job. "Flushing" it from the back side with clear water (as was recommended by the instructions) was not adequate.

    2. Because my cleaning job was not thorough and not frequent, the filter essentially plugged and caused other unfiltered air leakage into the duct system to occur. It was that unfiltered air that deposited the dust that the technician was concerned about.

    I took the A+2000 outside and used strong nozzle pressure to clean it. A lot of additional dirt came out of it. I then sprayed the back side of the filter (the "flush" side) with Windex to add a bit of soapy water to the situation and resprayed it good with strong nozzle pressure. A whole lot of more dirt came out this time suggesting to me that household oily contaminants were part of the pluggage problem. After drying the filter, it now looks like new and seems to be ready for additional service.

    I plan to clean it well on a monthly basis with high pressure water and some detergent solution and see if a reinspection by the technician in 3 or 4 months gets better marks. I think the filter was working - I wasn't! The cleaning process only takes 15 minutes - and the filter is ready for re-use. I have also gotten a number of comments from several other sources suggesting that a "super filter" such as the 3M pleated type could be "over-kill" and force me into a very expensive monthly (or sooner) replacement routine - which if not followed carefully would result in low air flow and the same kind of situation I had which started this whole discussion.


  11. #11
    Glad you were able to come up with a reasonable solution.

    FYI
    My information on device pressure loss comes from manual D and presumes a clean filter.
    It shows .03 as the minimum value that is used, unless otherwise stated by the manufacturer.

    Also, a pre-filter is quite common in many systems.
    There is absolutely nothing wrong with using 2 filters as long as the system is designed for 2 filter use and has been correctly sized.

    [Edited by chillbilly on 05-08-2005 at 11:59 AM]

  12. #12
    Join Date
    Mar 2002
    Location
    Eufaula OK
    Posts
    4,175
    The single most often cause of shortenrd equipment life is poor air filtering, either too restrictive or allowing unfiltered air to pass.
    The filter is not there to clean the air in your house, it is there to protect you equipment. There is nothing better or cheaper than throw away Fiberglas filters in a good sealed mount, and changed regularly.
    Jax

  13. #13
    Join Date
    Apr 2004
    Posts
    7,680
    Chilly is right, double filters are used fiarly often but as he says the system has to be designed with that in mind. Just to add a second filter in your case is asking for trouble though.

    Cracker Barrel resturants use double filters around here, they have filter grilles for the fiberglass and pleated filters in the units around here. I think they change the filters monthly in the grills and every 2 or 3 months in the units. To be fair, they are designed with that in mind and they are commercial units that have compairatively littel duct restriction versus a residential system and more control over the fan set up.

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