SAN DIEGO, CALIFORNIA – Too often, out of sight means out of mind, especially when it comes to air filters. Still, heating and cooling expert Gabriel Carini says changing them on schedule is vital for the residents’ health and the effectiveness and life of the unit.

“Filters keep dust and dirt from entering HVAC equipment and prevent pollutants from being spread throughout the home,” says the owner of Carini Heating, Air and Plumbing in San Diego.

The indoor comfort system ductwork functions as an expressway for pollutants like pollen, pet hair, dander, mold spores, dust mites, mildew, smoke, odors, and bacteria. A high-quality air filter removes them from air circulation, but filters must be replaced or cleaned regularly to be effective.

“If the filter is full, it’s not catching all those pollutants, and you are breathing them instead,” says Carini. “This can cause or aggravate allergies, asthma, and other health problems.”

Clogged filters also make the heating and air conditioning unit works harder and use more energy to maintain the indoor temperature. Letting dirt, dust, and other particles get into the equipment cuts down on life expectancy and increases the chance of a costly air conditioning or furnace repair.

“I recommend homeowners use the most effective filters that are compatible with their home comfort systems and their budgets,” says Carini, who is an expert in residential central air heating in San Diego County. “They should inspect filters monthly and replace or clean them as needed.”

There are many air conditioner and furnace filters to choose from with different sizes, efficiencies, designs, and quality. The main filter types are reusable, disposable panel, pleated and electrostatic pleated. Carini says pleated air filters are the most common because of their effectiveness, convenience, vast efficiencies, and design characteristics. He cautions homeowners away from the inexpensive fiberglass panel filters because they are not very effective and do little to protect the health of the HVAC system. Some filters have carbon to help eliminate odors or electrostatic to attract and trap dirt more effectively.

Instead of the brand or price, homeowners should look at the Minimum Efficiency Reporting Value to determine the quality of a filter. The rating system was created by the American Society of Heating, Refrigerating, and Air Conditioning Engineers. The MERV rates filter from one to 16. The higher the number, the more efficient the filter removes indoor air particles.

“A filter with a MERV 12 is the best balance between airborne particulate removal and overall heating and cooling system efficiency,” he says. “Anything higher than 12 is going to cause too much drag for the standard residential HVAC system to handle effectively.”

The system manual lists the indoor comfort system’s size, recommended type, and maintenance schedule. It is crucial to find out this information because some systems have multiple filter locations and even multiple types of filters. Heating and air conditioning repair, service, and installation technicians can help homeowners determine this information.

Measurements are typically printed on height, width, and depth on the air filter frame. Sizes are standardized, but a filter listed as 24 x 24 x 1 will measure something like 23 7/8 x 23 7/8 x 1/2. Custom-sized replacement filters can be ordered online.