Central System Air Filtration for Health and Equipment Protection
Central heating and cooling systems for the home have become complicated and computerized for efficiency and safety. The sensors in the units monitor operating temperatures of and airflow through cooling coils and heat exchangers. One of the functions of the air filter(s) in your system is to protect those heating and cooling surfaces from dirt buildup.
Air Filtration for Equipment Protection and Efficiency
These two filters show the extremes of operational condition. The new filter allows maximum airflow for heating and cooling efficiency. As the filter collects dirt, the air is obstructed, flow reduces, and less conditioned air is delivered to the space.
Reduced airflow can also become bad enough to cause damage to equipment or to create performance problems when sensors cut the unit off to protect it.
For many households, the equipment and airflow efficiency considerations are the only reasons for changing filters or for selection of their filtration quality. For many others, the indoor air quality for occupant health is important as well.
Air Filtration for Occupant Health
While the simplest and least expensive air filters can be enough for equipment and efficiency if changed frequently, they are not what you need for healthy indoor air.
This image from NIH.gov shows some of the long-term possible effects of indoor air pollution. Granted, these are not the results you should expect, but if getting better air filtration for your home can help to improve your health, why not do so?
Tighter Homes are More Efficient, but Also Create Air Quality Issues
The past decade has delivered vast improvements in efficiency and utility cost reductions through tightening of home construction. The goal is to minimize the sources of air leaks into the home, or heat loss out of the home in winter.
The problem is that, as the home gets tighter and less air can get in or out, the air inside can become a health hazard due to pollutants that can’t escape and just become more concentrated over time. The more efficient your home, the more important high efficiency air filtration becomes.
Air Filter Types and Efficiencies
The most common and least expensive of central system air filters are usually one-inch thick and composed of woven fiberglass. T
hey stop the largest of particles and dirt, those that would clog the system coils or damage equipment. They are of little value for improvement of indoor air quality for the health of occupants.
These fiberglass media filters let through a great many air pollutants, as their particle sizes are small enough to pass right through them.
Going up a notch in filtration efficiency are the filters you see made of pleated media. They can be different media materials, but they are more efficient at filtering out smaller particle sizes.
The trade-off for better filtration is the restriction or slowing of airflow. This extra air resistance is why they are pleated. This increases the area of the media through which the air can flow. You can get these in most standard filter sizes for one-inch thick filter racks.
If you change out your filter assembly to allow for thicker media, the choices for higher filtration efficiencies increase a lot. Filter efficiency is mostly measured by the MERV rating, the filter’s ability to filter particles from 3 to 10 microns in size. The smaller the particle size it will catch, the more efficient the filter. The higher the MERV rating, the more efficient the filter.
The electronic air cleaner is very efficient. The image is of the interior of one of them. Using an electronic charge on the plates, the filter attracts the particles to the plates as they pass through.
The cost of the filter and installation is higher, and you may find that one of the other types will provide the indoor air quality you want at a far lower upfront cost. However, there will be ongoing replacement costs.
Consult a professional about indoor air quality and your choices for filters for your system. Your health is important, and the COVID-19 pandemic raised home indoor air quality in importance for many homeowners.