Choosing the Right HVAC Air Filter

The best way to find out which air filter is the best for your heating and cooling system is to be aware and knowledgeable about the different types that are available.

There is no doubt that air filters will always be an important component of heating, ventilation and air conditioning. Unfortunately, numerous homeowners do not understand the importance of changing these devices on a regular basis.

The filter is often overlooked since it is not easily noticeable and gradually loses its efficiency. Besides, not all of these products have been manufactured to guarantee the same cleanliness and effectiveness. It also does not match all HVAC systems.

Specialists say that average disposable filters are just five percent effective although these contrivances are capable of keeping away unsafe particles. Pleated filters can deal with allergens and are roughly 40 percent useful. Washable electrostatic filters can be almost 95 percent cost-effective. The air filter you purchase will depend on your air conditioning unit and comfort requirements.

Reasons for Replacement

AC filters must be replaced regularly because of the following reasons:

  • Unclean filters are frequently the major cause of appliance malfunction. If the component is blocked with dirt, dust or dander, air flow is restricted. This hampers air movement and the fan will easily bog down. It causes unwarranted pressure on the system and burns out the fan motor.
  • Congested filters make air condition systems work harder to siphon clean air. It is a waste of electricity and naturally increases your monthly electric bill.
  • Filthy filters allow grimy particles to go through vents which increase the amount of dust in your home. This can exacerbate allergic reactions and respiratory ailments. In fact, individuals with life-threatening hypersensitivities or weak immune systems should opt for electronic filters. This model has the capacity to strain cold viruses. The HEPA electronic cleaner can even exterminate molds that usually accumulate in AC units.

air filter

HEPA stands for HIGH EFFICIENCY PARTICULATE ARRESTANCE. It is a special type of extended surface, deep-bedded, randomly positioned fibrous material media. The True HEPA Filter was developed during World War II by the Atomic Energy Commission and was designed to remove radioactive dust particles from the air, which might escape and present a health hazard to the researchers. Radioactive dust particles only attract and adhere to HEPA material. True HEPA Filters are regarded as the best form of air filtration. Hospitals, laboratories, even NASA spend thousands and even millions of dollars to create contamination free environments called Clean Rooms to help eliminate foreign particles, infectious agents, heavy metal particles, and a variety of other undesirable contaminants.” (Source:

Majority of these air guards last for three months depending of course on several factors:

  • Quality of the product you buy
  • Efficiency of the filter
  • Level of pollution
  • Presence of children and pets in the house

People living in places with higher count of pollen or the fine substance produced by flowers and dust may have to change the filters time and again.

This can be a do it yourself task. Filters are found near air handlers of HVAC systems. The handler is the box that contains the motor and fan. Most of the units you purchase have small hinges which permit easy access to the sieve. All you need to do is remove the old filter. Make sure not to shake the component or dust and fragments from the old filter. It is advisable to hire a technician if the system has irregularly-sized or multiple filters. A lot of HVAC manufacturers offer maintenance plans with regular filter changes.
There are different concerns and variables to take into account when choosing air filtration systems. The key is to concentrate on protection of the air movement equipment or protecting the house occupants. Low to medium effectiveness filters are designed to keep the appliance clean.

Testing Techniques

In 1968, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) designed testing standards to determine the performance of air-conditioning filters. This is known as Standard 52-68 which was modified first in 1976 and later in 1992. It has been labeled as ASHRAE Standard 52.1-1992. Nonetheless, the benchmark could not be explained easily and became confusing. To provide consumers more specific details, another document described as ASHRAE Standard 52.2 was developed. It identifies the filter’s functions on precise size ranges of particles. These are now the Minimum Efficiency Reporting Value or MERV levels.

MERV offers people a clear comprehension of the expected removal percentage for specific particle size varieties. Range E-1 is meant for particles within the 0.3 to 1.0 micron range. E-2 is for smidgens within 1.0 to 3.0 micron span. E-3 is for grains 3.0 to 10.0 micron scale. The filter is tested based on the three ranges. Performance is graded numerically from 1 up to 16. Familiarity with the MERV level of filters will help ensure minimum performance standards that can be planned carefully. Reliability is a must. It will be practical to check with filter experts who can assess and explain different MERV levels.

According to Wikipedia,

air filter

The MERV scale represents a quantum leap in the precision and accuracy of air-cleaner ratings and allows for improved health, reduced cost and energy efficiency in heating, ventilation and air conditioning (HVAC) design. For example, a HEPA filter is often impractical in central HVAC systems due to the large pressure drop the dense filter material causes. Experiments indicate that less obstructive, medium-efficiency filters of MERV 7 to 13 are almost as effective as true HEPA filters at removing allergens, with much lower associated system and operating costs.”

User-friendly Components

To their credit, manufacturers have been able to develop a broad array of user-friendly filter products. Certain panel filters (pleated and non-pleated) have MERV levels of below 12 are cheap. However, these are also low in terms of resistance to air flow and dust-removal capacity. High efficiency filters (above MERV 12) are more restrictive to air movement.

Actually, the new array of top-quality products offers better abilities while functioning at resistance intensity similar to those of panel filters. Some of the new products have distinct media pack models that lessen configuration damages through the filter. Others have threadlike filters which allow the air to cross with lower resistance. At the same time, there are filters with multiple dimensions allowing majority of systems to be improved quickly. In the past, it was extremely hard to upgrade without taking away the current frame and replacing it with a universal system primarily designed for panel filters. Concentration should be in providing products that will match equipment without the need for any adjustments.

Reliable Filtration

With all the information provided, how do you select the best air filter? Try to ask these questions before you settle on an air conditioning filter.

  • Does the existing filter function well?
  • Does it maintain the air handling equipment properly?
  • Does it make the air safe for the residents?

If the present filtration system performs credibly, changing the MERV level may not be logical at all. On the other hand, look at the options that will reduce energy costs and eventually result to lower operating costs on an annual basis. Try to select a filter that operates at decreased pressure drop since this also generates substantial electricity use. Moreover, the use of long-lasting filters should trim down maintenance costs through reduction of filter replacement annually. Foregoing just one regular filter replacement saves man-hours and money while sustaining performance levels.

According to, there are many options if the objective is to keep the air handling equipment cleaner. “Once the MERV level of existing filters is identified, it is easy to consider upgrades. The highest performance that can be expected from a MERV 6 is 49.9 percent removal of 3.0 – 10.0 micron size particles. If you upgrade to a MERV 8, this will increase the upper-end efficiency to 84.9 percent for the same particle size range. That is a 70 percent improvement in efficiency and the difference in product cost between a MERV 6 and a MERV 8 is relatively small. Keeping the equipment cleaner offers many benefits; one of the most important is operating with cleaner coils. Coils laden with an insulating layer of dust and dirt are much less efficient when transferring heat or cooling to the circulating air. This results in the system having to run longer to provide the desired temperature, which wastes energy. It is so easy to improve that part of the air handling equation by simply using a higher MERV level product.

Protection of AC Units

You need to protect the air conditioning unit and in the process take care of your investment.

There are factors to consider such as the following:

  • Drop of Pressure – Air handlers (blower motors) are prone to damages. Air flow is drawn through the pipes several times. An inferior air filter lets debris to go through and build up in the motor. When the filter is blocked, the blower is forced to work harder to siphon air. This causes the overworked motor to break down.
  • Ductwork – Try to detach the air supply outlet or grille if you are interested about the class of the air filter. Observe the air cylinders. In case you notice molds, fragments and dust, it is most likely that these will also gather on top of the evaporator coil as well as other components. The remains can be extricated and go through the living spaces. The unwanted spores will continue to move around in your abode. Inspection of the ductwork may be necessary especially if you have not done this for many years.
  • HVAC issues – The blower, handler and compressor work double time to deal with filtration problems. Hence, the air conditioning unit consumes more electrical power just to function continuously. The truth is filter problems can increase energy use by as much as 15 percent. This is the advice of the Department of Energy and should be taken seriously. Poor performance of your HVAC produces a lot of discomfort for homeowners.
  • Other parts – The evaporator coil can hold up air movement due to accumulation of dirt. Once heat exchange is hampered, the compressor and other electronic parts can experience a glitch.

Ratings of Filters

The final aspect for discussion is the rating and design of your air filter. An article published in the says that the “US Department of Energy does not mandate air filter manufacturers to use a universal efficiency-rating system, such as is used for rating the cooling and heating efficiency of heat pumps. Without a universal standard required on all air filter packaging, the task of choosing the right air filter isn’t always easy. An effective strategy, however, is using multiple ratings to compare particulate-capturing efficiency, filter longevity and pressure drop.”

Most air filters are available in several materials. You have to consider the method of capturing air particles; permanent or disposable model; filtration and maintenance; and costs. Designs include the following:

  • Disposable Fiberglass
  • Disposable Pleated
  • Electrostatic
  • High-Efficiency Pleated

The first is made up of flat panels which are generally MERV 4 or lower. This should only be considered if you are cost-conscious and after the basic protection factor. The second says, “Disposable pleated: Low-cost disposable pleated filters are typically mid-efficiency media that offer nice particulate-capturing qualities and easy maintenance. Just throw away the exhausted filter and replace it with a new one typically every one to three months (or as suggested in the packaging material.” (Source:

Electrostatic filters can either be thrown away after use or are for long-term/permanent use. The latter is the washable variety. Both varieties have self-charging cotton filaments that make use of attraction and force of collision to catch air particles. The permanent type can last for a maximum of eight years and is therefore economical. Nonetheless, there is the maintenance aspect which is quite rigorous. It calls for machine-washing to take away the molds and air-drying prior to replacement. The pleated filter is thick and entails special installation procedures in the ductwork. It is meant for superior air conditioning protection and quality air inside the house.