No filter is going to work 100%. The ones that filter better tend to
block flow and this is bad. Two filters block more flow than one. They may
trap more dirt, but life is full of tradeoffs. I would stick with just
return air filters or a single filter at the furnance.
I like MERV8 as a good compromise between cost, back pressure, and
particle size. MERV8 is usually the most porous of the widely
available paper pleated types and will stop most pollen and all
visible dust. Pollen is my main concern (due to hay fever) and they
do a good job. The next smallest particle filter practically doubles
in price, and causes over twice the back pressure but the extra dust
it captures is not worth the price or backpressure IMO. The next
filter down is usually a fiberglass pad that has little back pressure
and is cheap but doesn't catch most visible dust and no pollen. An
alternative would be to use a cheap pad filter on the ducts and a
MERV8 on the air handler, this will keep the big "dust bunnies" out at
the beginning so the MERV8 only has to do the pollen and small dust at
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.