The unsung hero in your home's central air conditioning and heating system is its filter. These workhorses silently strip potentially destructive and allergy-inducing particles from the air before they have a chance to damage your system or make you sick. You may not be aware there are actually several different types of air conditioning and heating filters in use. Each has its own advantages and disadvantages, so it can pay to be educated about their unique characteristics. Below is more information on the variety of air filters that are available for your use:
Fiberglass Panel Filters
The least expensive and most common type of air filter in use is the fiberglass panel filter. This filter type consists of a simple cardboard frame with multiple strands of fiberglass stretched from side-to-side. A thin piece of sheet metal is often included in the filter to add rigidity.
Fiberglass panel filters don't cost much, and they are excellent at filtering particles that could potentially damage a central air conditioning and heating unit. In addition, they permit units to operate at maximum levels of efficiency due to their less-restrictive air flow. However, fiberglass panel filters do not generally clean the air of allergens and other potentially harmful contaminants. They require frequent replacement, as well, which can be an inconvenience to some homeowners.
Pleated Paper or Cloth Filters
The next most likely filter type to be encountered in a residential setting is the pleated paper and cloth filter. These filters are similar in design and shape to panel filters, but they use an entirely different medium for filtration. Instead, pleated filters contain accordion-folded layers of paper or fibers that clean the air.
Pleated filters are better than panel filters at removing particles, and they don't need to be replaced as often; however, they can be inefficient due to their restrictive mode of operation. Pleated filters have an advantage in making the air cleaner; however, they also place more demands upon the fan motor. This results in increased operating expenses and potentially shorter equipment life.
High-efficiency particulate resistance (HEPA) filters are capable of filtering particles smaller than a single bacterium, and that makes them ideal for use in homes where clean air is paramount. For a filter to designated as HEPA, it must meet certain federally defined standards, so not just anyone can claim their filter is HEPA without official verification.
HEPA filters are also extremely restrictive of airflow, and many residential units are incapable of pushing sufficient air volumes for their use. If a HEPA filter is necessary due to a home occupant's medical condition, then it will also be necessary to consult with a qualified air conditioning and heating specialist, like Biggerstaff Plumbing Heating & Air, to determine the best options. Besides replacing the entire system, which may be cost prohibitive, other options may be better such as using standalone HEPA filtration systems.
Another option for homeowners who desire superior filtration at a reasonable cost are electrostatic filters. These filters use the same principle of "opposite attracts" that causes magnets to stick together. As the air from the unit's fan blows across the filter, it generates an electric charge that becomes "sticky" to dirt particles. These dirt particles are then trapped by the filter and become charged, too, thus perpetuating the cycle.
Electrostatic filters are reusable and that can be helpful for homeowners who don't want to constantly replace filters. They are washed clean on a regular basis and reinserted into the unit.
Unfortunately, electrostatic filters don't filter out large particles and can't pull mold spores from the air, either. This could pose a health problem for some individuals who need cleaner air than what can be offered by electrostatic filters. In addition, it can be easy to forget to clean the filter or fail to clean it as diligently as necessary, thus leading to a gradual buildup of debris inside the unit and air handler.