There is more and more concern about indoor air quality (IAQ). An advantage of the electronically commutated motors compared to PSC motors used in furnace and air handler blowers is that the ECMs are designed to operate continuously at a low speed to keep air flowing through the filters, constantly cleaning the air. Operating at a lower speed than what a PSC can, the operating noise of the ECM may not even be noticeable to the consumer.
In addition to constant filtering, the consumer wants the air cleaned to a greater degree. This has led to the use of filters that remove smaller and smaller particles of contaminants from the air.
Filters are rated by the size of particles that they stop from passing through into the air stream. This rating is the minimum efficiency reporting value, or MERV. The higher the MERV rating the smaller the particles that the filter is capable of trapping. When talking about filtering, the particulates being filtered are typically measured in microns (µm). There are 1 million microns in a meter. A coffee filter typically filters to about 20 microns. High efficiency particulate air (HEPA) filters will filter 99.97% of particulates that are .3 microns.
That sounds great! For cleaner air, install a higher MERV rated or HEPA filter. Not so fast! The higher the filtration, the higher the static pressure and the greater the restriction of airflow. This will reduce the amount of air moving through the living space, perhaps making the area less comfortable, and will also result in a shortened life of the equipment. The equipment manufacturer’s recommendation for static pressure and filter ratings should always be followed.
However, there are ventilator systems that are designed to be added to the furnace or air handler that would allow for greater filtering. Some are designed with multiple layers of filtering, including a HEPA filter. Because of the added static pressure that could be seen, some may be motorized.
CM3000 by Fantech
When trying to improve the IAQ of a living space, it may be OK to change to a filter that traps more contaminants but realize that it can diminish airflow. Always follow the recommendations of the equipment manufacturer when it comes to filters and static pressure. If changes in static pressure are too high when going to a more restrictive filter, perhaps installing a ventilator system can result in achieving the desired IAQ.