Disappointed by Lennox MERV 16
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  1. #1
    Join Date
    Aug 2003
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    906

    Thumbs down Disappointed by Lennox MERV 16

    Whereas the filter material itself seems fine, the box for it (e.g., Lennox X6661) leaves to be desired. When you make a MERV 16 claim, leakage around the filter matters a lot. There are multiple opportunities for air to leak into the return and for air to bypass the filter. There are:

    -Holes in the corners

    -Uneven mounting surfaces (both sides of the box -- one would need to apply caulking all around during installation to seal it off. Of course the installation instructions don't suggest doing that)

    -large tolerances (for a MERV 16 filter) between filter and box, and no gasketing around the top and incoming or outgoing sides of the filter

    -The "gasketing" that is present is open cell foam and also what looks like a pad of fibers with a low MERV rating, through which air can flow. Air can leak into the return as well through the open cell foam. The foam is in multiple pieces with small gaps in-between.

    The box looks great, is practical, and would be adequate for a MERV 6-8 filter. However, it can't possibly come anywhere close enough to be able to support a MERV 16 filter. I'm disappointed, although not entirely surprised.

  2. #2
    Join Date
    Apr 2002
    Posts
    11,808
    I would agree that leakage can be pretty significant

    Probably a hepa filter in an ASHRAE grade frame be a good thousand dollars per filter when you factor in the cost of the frames. 16 sounds like a notch below a HEPA, perhaps it is a lot cheaper in price as well, get what you pay for
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

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  3. #3
    Join Date
    Aug 2003
    Posts
    906
    Ah, you're talking about leakage between the filter material and the frame. I was discussing leakage between the frame and the housing. Sorry for being unclear. I agree both can be a factor, but in this case it seems that the housing is so bad that it could be improved significantly without reaching the thousand dollar price point. I'm not really asking for perfection or infectious disease-level air filtration. I'd just like something that isn't obviously inadequate.

    There's a good discussion of air leakage:

    "In reality, even small gaps can have
    a surprising effect on filter performance. For example,
    a mere 1 mm gap in the installation of a MERV 15 filter
    can reduce its efficiency to MERV 14. A gap of 10 mm
    can decrease performance all the way down to MERV
    8. "

    Bypass Air: What You Don’t Filter Can Hurt You
    The Effects of Bypass Air on Indoor Air Quality and HVAC Operating Costs
    By Ronald Cox, CAFS
    Market Manager, Kimberly-Clark Filtration Product

    http://www.kcfiltration.com/resource..._ByPassAir.pdf

    My guess is that adding the contributions of the gaps and leaky gasketing in (and into) the Lennox housing could potentially reach that magnitude (10 mm or MERV 8 installed performance).

  4. #4
    Join Date
    Apr 2002
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    11,808
    No what I meant is air will leak between the filter and the filter rack. or even right through where two filters butt up to one another.

    These ASHRAE grade frames are like an extremely low leak or "low bypass" filter rack if you will

    http://www.aafintl.com/Products/Repl...20Latches.aspx

    The Ammeriframe and renuframes in that link are like metal frames that hold a replaceable media. You can then use filters in these metal frames then use a holding frame like they describe as universal holding frames. These are like a gasketted frames that have latches and clips and hold the filters in place. On that same page they have some face loading frames like Astroframe etc where you face load and clip in HEPA filters.

    They also have the ASHRAE grade side access housing types, wich are a fancy filter rack where you slide pre-fitlers and HEPA filters in and they seal, with very limited bypass.

    http://www.aafintl.com/Products/Air%...0Housings.aspx

    So when you go for the high end type of filter, plus the special housing or holding frames, for HEPA its about 1000 a filter to start. Maybe the replacement filer is 300 or 400 after that.

    I looked at some systems where they had the ASHRAE grade filter system in the supply duct, but just a standard bank of filters that slid into a regular filter rack on the unit. From the corrosion you could see the path of fresh air in the mixing boxes as well as which side of the coil the mixed air was actually hitting. The coil side with the mixed air was dirty from particles bypassing the standard filter bank with 2 inch pleated media. The other half of the coil was clean.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  5. #5
    Join Date
    Aug 2003
    Posts
    906
    I see, the better racks (e.g. the welded bevel seal frame) require sturdy filters to withstand the sealing pressure from the gaskets, and the whole is expensive. Thanks for the links and information.

  6. #6
    Join Date
    Aug 2011
    Posts
    15
    Hi,

    Would this seal it up? Gasket tape? I was thinking of buying it in place of my honewell merv 10, it says it is interchangeable so I also read about this issue and am wondering as well.
    Last edited by HeyBob; 08-22-2011 at 06:47 PM. Reason: Removed Link

  7. #7
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    798
    im always really skeptical of anything over merv 13 as a passive filter.

  8. #8
    Join Date
    Aug 2003
    Posts
    906
    Quote Originally Posted by sallylikescleanair View Post
    SO you are disappointed in Lennox. I have customer who has a IQAir Perfect 16 installed in their home. The homeowner raves about it and she even got a certificate of improvement after the 1st hour. My husband is going to an IQAir training to see this system in the works. You should really sign up and see how their Merv 16 performs.. I know they are hosting an event in Indianapolis on the 21st I signed my husband up. He needs to see for himself if it is the very best like everyone says. Check it out maybe it will help you decide what you should be using.
    Maybe you should read my original post (and note the date). I tried it. I know how it performs. It doesn't matter if you use a filter that's MERV infinity if the box that it's in leaks air around it like a sieve. OOH! A certificate of improvement, well then I'll buy it (again)! Not. I have better, effective 24/7 and not just when the HVAC happens to run, with fresh air ventilation and humidity control, and at a fraction of the price of an IQAir. Read my other posts if you're interested. No "signup" and fees needed, and no rip-off either.
    -If you won't turn it on then nothing else matters.

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