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The Beauty of Whole-House Solutions to Air Filtration and Cleaning

For any household that wants to stay healthy, an efficient air filtration and cleaning system is a must. Air filters and purification systems protect your health by removing respiratory irritants such as pollen and mold spores. High-efficiency models can also address any Chicago city smog that finds its way into your home.

While portable room air cleaners have their place, their effectiveness is limited to a small part of your home. Whole-house systems provide you with clean air in every room.

With so many whole-house air cleaning choices available, though, it's not always easy to find the right combination of filters and air cleaners for your needs. If you're looking to improve your indoor air quality, start by learning a little about the air filtration and cleaning options available.

On a Tight Budget? Try Flat Panel Filters

Flat-panel or standard pleated filters are the type your furnace air filter slot was built to hold. The non-pleated, flat filters are the least expensive of all filter types, but also the least efficient. Because they can't hold much debris without becoming clogged, they need to be changed monthly in order to work properly and to maintain your system's energy efficiency.

To find a filter's efficiency, check its Minimum Efficiency Reporting Value (MERV) number. A filter's MERV indicates what percent of particles of a certain size it can trap. More efficient filters have higher MERV numbers. If the packaging does't provide the filter's MERV number, look for one that does.

Disposable fiberglass filters – Contractors install this standard filter when the homeowner doesn't request anything more efficient. With MERVs between 1 to 4, these filters can stop only the largest air contaminant particles. They're intended to protect your heating and cooling system's components from debris such as dust, lint and pet hair. They catch the particles that aren't small enough for you to breath in, but miss the ones that are. That means they do next to nothing to protect your health.

Disposable synthetic filters – These polyester filters are typically available in MERVs 5 to 6. As with lower-efficiency filters, their primary purpose is to keep your system's inner workings clean. They are, however, also able to trap a greater amount of respiratory irritants such as mold spores and smaller pollen particles.

Experts from ASHRAE, a trade society that deals with indoor air quality and related issues, recommend using a filter with a MERV of 6 or higher. If you want to spend as little as possible per filter and you don't have any health concerns, a MERV 6 filter is sufficient for rudimentary whole-house air filtration and cleaning.

Want Truly Cleaner Air? Consider an Extended-Media Filter

While cheap flat filters cover the basics, good air filtration and cleaning is about more than meeting minimum requirements. A higher-efficiency filter, one with a MERV greater than 6, will remove enough contaminants from your air to make a real difference in your health.

These are the filters you want if your goal is to keep your allergy symptoms, asthma attacks, and other respiratory complaints at bay. They not only clean the air better, they also last longer. Some need replacing only once a year, depending on the model and your home's air quality

In this efficiency range, you'll find the extended-media filters. They're called "extended" because their designs extend the amount of filter material that can fit inside the frame. The increased surface area means more space for the filter to trap contaminant particles. Extended media filters come in three main forms.

Pleated filters – In these filters, a cotton/polyester blend or synthetic material is bent into pleats. They're most often available in MERVs between 8 and 11, which stops nearly all pollen, mold spores, and even some bacteria. As mentioned before, they will fit into a standard air filter slot in your furnace or air handler system.

Rigid box filters – As the name suggests, these box-shaped filters are thicker than the standard 1-inch filters. This thickness gives them plenty of space to trap particles, so they can reach MERVs of 10 to 16. The downside of that is that they don't fit into the standard filter track and they interfere with airflow so much that most residential systems can't use them without mechanical alterations.

Bag filters – Designed in the form of in-line pockets, these filters offer the same level of filtration box filters do. Generally, higher-efficiency models are made with more and deeper pockets.

U.S. Environmental Protection Agency researchers have found that filters in the MERV 7 to 13 range are almost as good as HEPA filters when it comes to improving air quality. To help with respiratory conditions, the American College of Allergy, Asthma & Immunology recommend filters with MERVs of 11 or 12.

A higher-efficiency filter isn't always better, though. The more efficient a filter, the greater its density. Dense filters make it hard for contaminant particles to pass through, but they also interfere with the air flowing through. That forces the blower motor to work harder to maintain sufficient airflow.

In the average residential system, the motor simply isn't strong enough to handle the load. At best, your system's energy efficiency will drop; at worst, your blower motor will burn out. Before you buy a filter with a MERV higher than 10, consult a heating and cooling professional.

Supplement Your Filter with an Electronic Air Cleaner

Traditional air filters, known as mechanical filters, clean your air by catching contaminant particles on the fibers of the filter material. Filters with more fibers traps more particles, but they also slow down airflow more. This fact limits their usefulness.

Electronic air cleaners take a completely different approach to air filtration and cleaning. These devices rely on electricity to remove or neutralize harmful particles in your air. The most common type, the electrostatic precipitator, works by pulling particles out of the air, which allows it to remove even the tiniest contaminants without impeding the airflow.

A whole-house electronic air cleaner purifies the air in your home by taking it through three main components:

  1. Pre-filter – A fan pulls air into the air cleaner's mechanical pre-filter, which captures the biggest debris particles such as lint from clothing. This filter is in place primarily to protect the air cleaner's inner components.
  2. Ionization chamber – The air flows into a chamber containing electrodes that give the remaining contaminant particles either a positive or negative electric charge.
  3. Collector plates – The air and the charged particles flow through a set of aluminum collector plates. These plates hold the opposite charge as the particles. Oppositely charged objects attract each other. The metal plates attract the particles, pulling them out of the air and trapping them. Clean air then flows out into your ducts.

These air purifiers don't require replacement as filters do. You'll only need to clean the pre-filter and collector plates periodically to keep the device efficient.

Keep Germs in Check with a UVGI Air Cleaner

If someone in your home is susceptible to respiratory infections, you may want to consider air filtration and cleaning devices that target microbes specifically. An ultraviolet (UV) germicidal irradiation system is the most common choice for home use.

This system uses one or more UV bulbs installed in either your ducts or positioned to shine on A/C or heat pump indoor coils and other components that attract mold and bacteria. With the in-duct type of installation, as air passes though, the UV light hits the contaminant particles in the air. This light neutralizes viruses, bacteria, mold spores and certain other biological contaminants by damaging their DNA.

Well-designed UVGI air purifiers are highly effective and often used in hospitals to minimize the spread of infection. Because they work against biological particles only, you'll still need a medium- to high-efficiency air filter in your system to trap other types of particles.

Other Air Filtration and Cleaning Devices to Consider

Gas phase air cleaners – The activated carbon or other absorbent substance in these air cleaners removes volatile organic compounds (VOCs) as well as odor-causing particles from tobacco smoke and cooking. VOCs are chemicals given off by many household items and substances, including treated lumber, upholstery, carpeting and paint. These purifiers are sometimes built into electronic air cleaners, but can also be installed separately as an additional air filtration and cleaning method.

Photocatalytic oxidation (PCO) air cleaners – These devices are also designed primarily to reduce VOCs. They work by shining a UV light on a titanium dioxide catalyst. The resulting reaction produces molecules that oxidize VOCs, rendering them harmless. Because they produce small amounts of ozone, a lung irritant, PCO cleaners aren't appropriate in homes where someone has a respiratory condition.

Ion generators – The negative ions produced by these devices latch onto larger particles, causing them to fall to the floor or stick to walls, furniture and other items. This makes the particles easier to remove when you mop or dust. Over time, though, they may cause dirt streaks on your walls and elsewhere.

If you're in the Chicago area or nearby in northwest Indiana or southwest Michigan, use our find-a-contractor service at to get in touch with a local provider who can help you improve your indoor air quality, save energy, and keep your heating and cooling equipment in top shape.

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