How an air filter is part of a durable home
The filter's main purpose is to filter the air before it blows over the coil. When the coil of your HVAC system becomes dirty, it will not perform correctly or to the correct efficiency. This can drastically reduce airflow and, therefore, lead to an early furnace failure.
For the longer life of your HVAC system, you need to maintain clean filters and a clean coil. Did you know the service tech should actually wash the coil off when he comes out? Neither did I, until recently working with some experts in HVAC design and operation.
What about filer bypass, i.e. air blowing around the filter?
This is a huge mistake for HVAC techs to make. If your filter is not in a tight-fitting box to reduce filter bypass, you can bet the coil is dirty and the system is inefficient. My favorite is the barn door some contractors make in return and then throw the filters in a V-shape from the street! What rocket science professor came up with this? Or, was it a installer trying to quit early and had a huge metal sheer in his truck? The door does not even fit tight enough not to allow your cat to crawl in. You need to demand a proper filter box and a proper filter (8 Merv or higher).
What about filtering air?
One solution is the Venmar system www.venmar.ca with heat recovery. This is an ideal system for filtering whole houses with a HEPA filter that filters out 99.97% dust and airborne particles as small as .3 microns ( one human hair is 150 microns). This will reduce allergy symptoms and Asthma, recurring colds, and persistent coughs.
Good luck out there!