Does Central Air Conditioning Have Good Filtering?

Poor Filtering

• The filtration used in central air conditioners may not be the best choice; the most inexpensive and widely available types of air filters for air conditioners are not always effective. The standard fiberglass-type of filters often sold for a few dollars in department stores do not filter out nearly enough debris for central air. Those who choose to use this type generally need their systems serviced and coils cleaned much more often than those who use better-quality types. Standard fiber-glass filters also tend to add slightly to utility bills because of their inefficiency. The washable aluminum-mesh filters are also among the least desirable. Cleaning the cooling coil every year is recommended when you choose this type of filter because of the high volume of material that gets through. The savings related to their repeated use is more than eaten up by service calls.

Good Filtering

• The standard polyester filters widely available and inexpensive are a bit better than their aluminum and fiberglass counterparts, but they still allow too many smaller particles into the system. You won’t need to have your coil cleaned as a result of using one of these filters very often, but it will be necessary about every five years. For the slight additional cost, they're a good buy when compared to fiberglass. Polyester pleated filters are generally 1, 2 or 4 inches thick and have much more surface area than the standard polyester filters. They also have a higher efficiency and hold much more dirt than the lesser types. The only downside is that they restrict airflow through the system, especially if they're not changed with regular frequency.

Best Filtering

• If you want truly good central-air filtration, HEPA filters are likely the best bet. HEPA, or High Efficiency Particle Arrestant filters are very dense and are pleated in the same way polyester pleated filters are designed. But these filters are held to a specific standard that requires them to filter out more than 99 percent of airborne particles down to 0.3 microns. This is by far a better option for good filtering when compared to the other common types. They also tend to get more efficient as they get dirty and do not need to be replaced as often. The downside is they cost more. They also typically need to be installed professionally. Some HEPA-type filters are also available, but they aren’t held to as high a standard.

Filter Maintenance

• Changing your air filters on the central unit is perhaps the most important part of HVAC maintenance you can do yourself. Replace lower-efficiency air filters every two or three months, and replace HEPA filters at the intervals recommended on the product packaging. If you fail to keep up with this maintenance, you will increase energy bills, potentially damage your central unit and you could even cause fires from overheating.