On Wed, 22 Oct 2008 09:36:09 -0700, "Bob F"
wrote Re is it always better to use a thicker filter in furnace?:


"dpb" wrote in message ...
james wrote:
My furnace was installed with a 16x20x1 pleated filter.

It looks like there is enough space to fit a 16x20x2 filter. This should last
longer and reduce air resistance.

Is there any reason not to?

How can doubling the thickness _reduce_ resistance?

It doubles the surface area.

So if you could rig 4 filters it would reduce the resistance more? And
if you could put 8 or 16 filters you could reduce the resistance to
almost zero.

I don't think so, unless you rig the filters in parallel.