Home inspectors should impress upon their clients the importance of proper maintenance of their home’s HVAC system.  The most common maintenance task is regularly cleaning or replacing the filter for the unit’s optimum energy efficiency, as well as the home’s improved indoor air quality.  And a high-rated MERV filter box may be an option that can be retrofitted to an existing HVAC unit.  Read more about it Inspecting for Proper Installation of HVAC Filters.