Air flow ratings on furnace air filters?


I cannot find any "real" measurements of the airflow through various filters, 3M vs. Accumulair vs. fiberglass filter, etc. I just find discussions about "this one being more restrictive than the other" or that 3M Filtrete purple has 15% more airflow than 3M red, and so on. It's all very unscientific, just people saying whatever they guess based on how much dirt appears and how much the filter warps toward the fan.
Is there an objective measurement somewhere? For example in some test setting when starting clean, fiberglass flows A amount of air, 3M purple flows B amount of air, Accumulair Gold flows C amount of air...
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Im in the business.... at the consumer level they dont give good ratings..and when they do the ratings are for a clean filter...and of course your rating will be half way between a clean and dirty filter.
Best move imo for perfomance and pressure drop is to buy a 2" thick Pleated filter... thats about 4x the surface are aof most other options and these are inherently more efficient on the same size particles...about 30% efficient clean.... pressure drops in the range of .25" or less water column dirty at 500 fpm face velocity..
for figures search out Flanders Air filter technical data... they sell mostly high end HEPA filters...but also the residential type 2" pleated filter... they will have complete information.
for you though most effort is wasted..you can only do so well...and dont have room in your furnace for more than a 2" thick filter regardless.
For near zero pressure drop though, you can go to a pure electronic filter, wires and plates. with oversized 15% prefilters (set in on a V pattern for a 200 fpm face velocity...well worth it if you have alergies or live in LA etc. cost about 2500 dollars installed.
beyond that, if your ducts leak air and most do, 10% or more...thats a much bigger issue. get some duct sealant compound and go over all the duct joints... that will be a big savings for you.... if its an older furnance the blower wheel vanes will be full of dirt, wasting much energy... you can clean those out also.
Phil scott
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phil scott wrote:

Take a look at a Grainger Catalog. They do offer some performance data. For some of their filters you'll find pressure drop vs. flow as a function of particle size removed.
http://www.grainger.com/Grainger/wwg/catalogPDF.shtml
Start a page 3856 in their current catalog.
Boden
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...interesting, thanks Phil. I found a table with some real pressure drop data:
http://texairfilters.com/news/testsonpressuredrop.htm
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scorpionleather wrote:

So what do those numbers mean?
Lou
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Envirosept is an in-between 2-watt 7 kV charged media filter with good particulate performance and a 0.1" H20 drop at 225 lfm.
Nick
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responding to http://www.homeownershub.com/maintenance/air-flow-ratings-on-furnace-air-filters-334923-.htm moshei wrote: so when choosing a furnace filter, keep in mind your needs as well as price and what features each particular style has to offer!
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