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...
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
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.
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.
Start a page 3856 in their current catalog.
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