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  1. #1
    Join Date
    Jan 2009
    Posts
    56

    Best type of filter for residentail forced air heating/cooling?

    Hi,

    I bought my house last year and have been using the filters that the previous owner had, but I've come to wonder if really they are any good and/or if there is something better that I should be using.

    My house is 43 years old and I have a bi-energy furnance/heat pump. The filter unit on the furnace was at one time a Honeywell electrostatic filter, but the electrostatic filters themselves have long since been thrown away, and the only thing remaining is the unpowered "box/cabinet" which is installed in the duct work. The main stack is 20x20, and the honeywell box extends that a little to roughly 20x22.

    Currently, there is an 20x20x1 AAF Internation ElectroKlean filter installed (http://www.aafintl.com/Products/Repl...ctroKlean.aspx). The good thing about it is that it is reusable. I'm wondering if that's the only good thing about it though.

    I realize that it isn't a HEPA filter, but I'm fine with that. I'm not convinced that putting a HEPA filter on a 43 year old HVAC system would really do a whole lot.

    Is this filter any good? Are there better things out there to use instead? The big box stores sell the simple paper ones for 3-5$/ea. Are those better than something like this?

    My knowledge of HVAC filters is fairly limited at best.

    Thanks for any insight, tips and knowledge that you can share!

    Eric

  2. #2
    Keep in mind that the original purpose of HVAC system filters was to trap dust that would otherwise compromise system performance by getting stuck on fan motors and blades and in ducts and on the condenser coil. Only fairly recently have filter manufacturers started introducing filters that serve the secondary purpose of filtering small airborne particles that people don't want to breathe. The fact that your system is 43 years old doesn't have too much bearing on whether to use a HEPA filter; if you want HEPA-filtered air in your house for the next 3 months, then buy and use a HEPA filter, and if you don't care, then save your money and stick with what you've got or go with the traditional style spun fiber filter.

    The drawback to any filter, including the washable one you've currently got, is that it can restrict airflow excessively to begin with or when it gets dirty. And if your system is operating on reduced airflow, it can a) cost you money because of reduced efficiency and b) ruin your equipment after it has to work too hard to provide cool air, or if reduced airflow causes your condenser coil to freeze, etc. On the other side of the coin, the obvious benefit of your washable filter is that you don't have to keep spending money to replace it.

    Everyone has their own opinion, but my view is that a lot of people run out and buy fancy and expensive filters because they've been sucked in by advertising hype rather than a thoughtful examination of their own needs. Go to Honeywell's website (as just one example) and you'll find "sell sheets" designed to help professional HVAC sales or installation personnel convince people that they need fancier stuff in their system (which some people, although probably not all, may want or need).

    If you have a relatively clean house (e.g. things like no kids opening the door to the outside constantly, no pets, central vac that exhausts to the outside, etc.), then I'd say keep your washable filter and be diligent about maintaining it, and things should be fine.

  3. #3
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,316
    they make filters that are 4" pleated filters that have a 1" lip to fit into
    existing r/a grill. don't have the link to the site, but have seen them at
    hvac supply stores. these filters work well..are not reusable, cost more
    but they work. they also don't have to be replaced as often.

    if r/a is not sealed dirt/dust is sucked onto/into coil.
    so sealing r/a before installing the better filter keeps
    the coil from becoming dirty.
    duct leakage also contributes to dirt/dust/insulation particles from
    being recirculated thru system and into your house.

    washable filters suck, rockstoppers suck. both literally and figuratively.
    electrostatic filters ...see above.

    based on my experience & testing of filters and air flow.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  4. #4
    Join Date
    Sep 2006
    Location
    Montana
    Posts
    983
    When it comes to air filtration, I would strongly recommend staying away from the fiberglass filters, they do very little except for catching the big particulates. A pleated filter would be the way to go if you're only looking for a 1" filter. I personally don't like the electrostatic filters because unless cleaned often and properly, they end up restricting air flow. IMO, the only way to effectively clean an electrostatic filter is by using a pressure washer. Over time, so much dust gets embedded into them, they get harder and harder to clean. If you don't mind spending a little money, I would have a media filter installed. These are usually 4" to 5" thick and only need to be replaced once, maybe twice per year. I'm a fan of Aprilaire's spaceguard filters. I would check out their website and do a little research on them.

  5. #5
    Join Date
    Dec 2002
    Location
    Toledo, Ohio, United States
    Posts
    12,921
    Coleman

  6. #6
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,316
    1" pleated filters are better than rock stoppers but
    can be vey restrictive. I did a test using different filters
    but unfortunately didn't keep (or can't find) the actual #'s
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  7. #7
    Join Date
    Jan 2008
    Posts
    2,117
    5" media air cleaner is the best in my opinion.
    Very affordable, and they last 6 months to a year. Keeps all the crap out of your system.
    Might need some tin work to make it happen, but it can be done in most any situation.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  8. #8
    Join Date
    Aug 2010
    Location
    Northern California
    Posts
    64
    Make sure your static pressures are ok enough to handle advanced filtration. I would personally recommend the trane clean effects. If you don't want to spend a few thousand dollars, then go with the micro power guard. Check out this website for a lot of good reading.


    www.4natureshome.com

  9. #9
    Join Date
    Sep 2010
    Posts
    14
    Does the MERV ratings matter here? I try to buy as high a MERV rating as I can (currently on MERV 13 from nordic air). Am I just being a sucker?

  10. #10
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,306
    MERV is how small of stuff the filter can catch. The higher the merv rating, the smaller particles it catches.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  11. #11
    Quote Originally Posted by ron-u View Post
    Does the MERV ratings matter here? I try to buy as high a MERV rating as I can (currently on MERV 13 from nordic air). Am I just being a sucker?
    The question is why do you buy high MERV rating filters? If you can't come up with a reason other than something like "they're more expensive so they must be better" or "more particle catching must be better than less particle catching even though it's well beyond what's required to keep my HVAC system operating effectively" then yes, you're probably throwing away money.

  12. #12
    Join Date
    May 2008
    Location
    Portland, OR
    Posts
    236
    MERV ratings matter if you have problems with allergies or other problems caused or aggravated by air quality.

    Otherwise, a good 'ol 1" pleated filter that's changed monthly will work well enough to keep your coil and blower free of dust and dirt.

  13. #13
    Quote Originally Posted by TxTurbo View Post
    MERV ratings matter if you have problems with allergies or other problems caused or aggravated by air quality.

    Otherwise, a good 'ol 1" pleated filter that's changed monthly will work well enough to keep your coil and blower free of dust and dirt.
    Exactly. And when the companies that make and market high MERV rating filters advertise that they're the same as those used on the space station and in hospital operating rooms, etc., they neglect to mention that those environments are either completely closed or effectively compeltely closed with positive pressure HVAC systems. In a home where doors to the outside keep opening and letting in relatively dirty air, a high MERV filter isn't as likely to have such a great impact.

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