Mike,


The 2400 is a very good product, good filtration with a low pressure
drop with air flow up to about 1200 CFM (3 tons cooling). Putting in a
1" pleated filter is likely to reduce air flow 15 to 30%, I don't
recommend them. NOTE: If your carrier furnace has a Variable Speed
blower, then go ahead and use the 1" pleated. The VS blowere can
overcome the extra resistance.

The pleated filter WILL NOT make your furnace more efficient or last
longer. It WILL help keep your AC coil clean over the long haul, which
will help air flow 15 years from now, but with a VS blower won't matter
as much.

A zoning system sounds like your best bet for your comfort problems.
Someone who does air balance may be able to help as well.

Stretch