There are many recommendations about the use of replacement filters. Some manufacturers suggest a monthly or bi-monthly routine of replacement. Other manufacturers indicate their filters will last several months. It is important, first, to know the type of filter and the particulates it is designed to capture. If you are using a standard fiberglass one-inch filter for capturing dust to enhance the operating efficiency of the heating and cooling unit, you can tell by examining the filter when it is time to change.

On the other hand, if the filter is designed to capture pollen, mold spores, dust mites, and odors, you cannot tell by looking at the filter if it should be replaced. Some of these pollutants are not visible to the naked eye. In this case, it is vital that the filters be replaced at regular intervals. Monthly replacement may be necessary if the pollutant content is obviously high. During the months of high pollen count, it is advisable to replace the filters monthly. If any chemicals are used such as an indoor painting project, change the filter as needed to remove the odor.

Carefully Evaluate Replacement Filters

Carbon filters are great at adsorbing odors, but once the surface is full, the odors will be allowed to pass on through the system and return to the air. HEPA filtering is almost a standard on portable air cleaners. It is often combined with a carbon pre-filter or some other type of filtering system that requires replacement.

Check for the CADR (clean air delivery rate) on the replacement filters. This will indicate the amount of dust, smoke, pollen, and similar pollutants the filter is designed to remove adequately. It is important to match the filter with the unit. Many companies offer filters that are interchangeable between different brands of air-cleaning units.