On Oct 22, 11:33*am, "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?

It is impossible to say from the information provided. The type of
material the design etc all make differences. The most important
factor is to make sure the filter meets the specifications given for
your furnace.

Personally I believe far too much worry is made about filters. You
need to meet the specifications for the furnace to protect it, but you
should not really expect some sort of real change in air quality in
your home because you use this or that air filter. Most of the
advertising related to air filters or all kinds are all fluff. They
don't provide any evidence that the products advertised add anything
to the quality of life in the home where they are used.