Duct mounted high efficiency filters can clean the air of things like
smoke and dust without degrading system performance significantly,
depending on the filter. The 1" thick pleated and washable filters
remove more dirt than standard filters, but reduce airflow by an
average of 10 to 20 percent. The 1" high efficiency filters also get
dirty faster than standard filters, so their resistance to air flow
increases fast. They should be replaced as often as standard filters,
not three months as stated on the filter package. They should be used
only if your airflow has been measured by a high accuracy device like a
flow hood and found to be adequate.
UV lights don't do anything for smoke but can kill bacteria and mold
spores. I have had limited success with UV lights, some brands are
better than others.
A TROLL is someone posting something ridiculous or mean, trying to get
a rise out of other group members, but not interested in serious
discussion. For instance, $2,000.00 seems very cheap for a new
furnace, indoor coil and condensor, even at 10 SEER. Did you get it
used? Or did you pay additional to get it installed?