Does a higher-end media filter introduce restrictions to the airflow and reduce the overall efficiency of the heating and cooling equipments?
For example Lennox's HC16 need filter replacement after yearly. Towards the end of the year, does the accumulation of dust hider airflow to the air handler?
Yes, high end media filters do restrict your air flow. If you have a new
system, hopefully it has been designed with this restriction in mind.
As filters get full of dust, etc., their restriction becomes worse, how
often depends on how dusty your home is. Each home is different.
The thickness of the media filter, also makes a difference ( 1" or 2").
Old a/c units can not handle these restrictions, and will have problems
when high Merv filters are installed.
Cheap filters usually have a Merv rating of 2, most of the time old
units can not handle 5 or above depending on the condition of your
system. A clean well designed old system can handle a Merv of 7,
but not many systems meet this criteria.