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All the world’s a stage, and some of the most interesting shows can be found…in the furnace filter aisle of the neighborhood big box store? With a sea of sizes and selection as a backdrop, players mill around mumbling incoherently—words like “micron” and “allergen” and “electrostatic” can be heard between moans, sighs and facial contortions. Sadly, these pour souls are just the store employees. Pity the poor customer who thought that writing down the correct size and thickness was all that was needed.

Luckily, the science behind home filtration has come a long way since Shakespeare’s day. Originally designed to help protect the HVAC (Heating, Ventilation and Air Conditioning) system, today’s furnace filter is on the front line in the battle to improve indoor air quality. Selecting the right filter is a balance between health, expectations, budget and possibly sanity.

In the past, filter changing was strictly a winter thing. When windows were opened to let in the spring breezes (and the bugs), the furnace system went into hibernation until fall. Today, more and more homes have central air conditioning that shares the same ducting and filtration as the furnace. Because air conditioning also removes humidity from the indoor environment, it is becoming common for homeowners to run their systems in the warmer months. In the south and southwest regions, the HVAC system will actually see more action in the summer than in the winter.

For people with allergies or breathing problems, the right filter is essential. The US Environmental Protection Agency reports that about 20 million Americans suffer from asthma, with the largest jump in cases involving children under five. Studies have found indoor air to be two to five times more polluted than outdoor air and most people spend 90 percent of their day indoors.

The good news is that making the proper choice requires neither a PhD in microbiology nor a prescription from your doctor. A basic knowledge of what is available and the function they perform is all you need to become a furnace-filter-finding-phenomenon!

Spun Fiberglass
At a few dollars each, these are the cheapest and most common type of furnace filter. They block most of the large dust particles, but smaller allergens, like pollen and mold spores, will pass right through. Because they are the thinnest of all filters, they are best suited for lower quality builder grade systems that cannot handle a thicker filter media. A spun fiberglass filter should be changed monthly.

Washable/Electrostatic
Slightly more effective than a fiberglass filter, the attraction of a washable filter lies in long-term savings. The initial cost is around $25, but they last for years. The downside is in the washing. In dustier climates they should be cleaned monthly, and that’s not practical for the typical busy homeowner.

Pleated Media
More surface means more filtration. A pleated filter combines a thicker filtration media to catch more particles, with pleats to increase the overall working surface, making it an effective and popular option. The cost is about $15, and they can last up to three months, depending on climate conditions. The thicker media may reduce the efficiency of builder grade systems.

Electronic Air Filters
For people with severe allergies or similar health related issues, the benefits of an electronic air filtration system might justify the initial cost of $700 or more. Using electromagnetic attraction, they can eliminate pollen and mold spores as well as many airborne viruses.

The most common HVAC maintenance and repair issues can be traced back to filter neglect. A dirty filter can’t do its job of cleaning the air and will actually contribute to air quality problems in the home. It also makes the system work harder and causes internal parts to get dirty, and that can lead to an inefficient system and expensive repairs. So whatever the filter choice, remember to clean or replace it often, as part of your scheduled home maintenance plan. Now, back to the store—there’s new guy starting today, and I’ve got front row seats!

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