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A Commercial Consumer's Guide
to Quality Features in Air Cleaners

(click on topic)

bullet Introduction
bullet What is an Air Cleaner?
bullet Why not just open a window instead of using an air cleaner?
bullet What are the important thlngs to consider when buying an air cleaner?



Indoor Air Quality affects your bottom line in more ways than one. Clients and customers feel better and stay longer. Current, tougher legislation on indoor air quality has made it more compelling than ever to clear the air of contaminants in every type of business establishment. The purpose of this guide is to inform you of available air cleaning technologies that meet today's clean indoor air standards. With this information you can make an informed decision in selecting the proper air cleaning system for your workplace.

Air cleaners use filters or electronic precipitators to remove particulate contaminants from the air you breathe. Many air cleaners also include a bed of sorption material to remove gaseous contaminants, as well. Contaminants removed by commercial air cleaners may include:

  • Tobacco smoke
  • Dust
  • Airborne microbes
  • Volatile organic compounds (VOC's)
  • Pollen

Many manufacturers offer air cleaners as "stand alone" units that include a fan for moving the air through the air cleaner. Other units are designed for installation in the building's heating and cooling system (HVAC system) and do not include fans.

  • Why not just open a window instead of using an air cleaner?(Top)
    • Unless you are fortunate enough to live in an area where the outside air is always between 72ºF and 78ºF, you'll waste the money spent heating or cooling the air in your home or business.
    • The air outside your home or business is not always as clean as you'd like, especially in urban environments.
    • Properly installed air cleaners generate better airflow patterns for removing contaminants than just opening a window.


1. Airflow Volume(Top)

Obviously, the more air that is moved through an air cleaner, the more air it will clean, if properly designed. Air cleaners are usually rated in cubic feet per minute (CFM). This number tells you how much air the machine will move.

How much airflow one needs is dependent on what's going on in the room. As a general rule of thumb, in a smoky environment (like a club, bar, breakroom, or lodge meeting hall) a 1,000 CFM machine will be adequate for 1,000 square feet if the ceilings are 8' to 10' high. The number of air cleaners required are determine by air changes per hour. The following formula will help you determine how many air cleaners you need for a given area.

a) How to determine the number of air cleaners required:(Top)

Measure the size of the room in feet and use these numbers in the following formula:

# of Air Cleaners =

L x W x H of room x Air Changes per Hour  
CFM of Air (see product literature) x 60 min.

L,W,H in feet

b) Air changes per hour (ACH):(Top)


light load (general offices, computer rooms, conference rooms): 4-5
average load (bars, breakrooms, designated smoking areas): 6
heavy load bingo halls, cigar bars, extra smoky areas): 8-10


2. Airflow Pattern(Top)

The airflow pattern established by an air cleaner must perform two tasks:

  • Get the dirty air to the air cleaner
  • Move the clean air throughout the room

Two basic designs are used to perform these tasks:

"Coanda" units move the air horizontally and vertically similar to a reverse flow ceiling fan. They also take advantage of the warm rising air and enhance this vertical movement by pulling the air up with a fan. The airflow direction is changed as the air passes through the machine and the clean air is blown out sideways along the ceiling. This clean air strikes the walls (or the clean air from other Coanda units in the room) and is circulated back down to the breathing zone.


Coanda1.gif (8323 bytes)


"Pass through" units take the air in one side and exhaust the air out the other, horizontally. These units are often used in pairs (or more) to establish a "race track" pattern of air movement around the room at ceiling height. This airflow pattern takes advantage of the normally rising warm air in commercial buildings to capture the dirty air. Mixing of air by the race track pattern returns clean air to the breathing area below. A "Pass through" air cleaner, operating by itself, will not establish an effective air flow pattern. If only one air cleaner is going to be installed in a room, the "Coanda" air cleaner would be the better choice.

racetrk.gif (7818 bytes)

3. Noise(Top)

All air cleaners make some noise as they move air through the machine. The amount of noise is affected by design features such as:

  • Fan or blower speed (faster fans/blowers are usually noisier)
  • Fan blade or blower design
  • Cabinet configuration (baffles and/or venturi plates with bell-shaped orifices help damp out fan noise)
  • Sound-adsorbent lining in the cabinet (Foam-like materials are commonly used)

The noise levels generated by an air cleaner are rated in decibels (dB). You can compare the dB ratings for machines that move equivalent CFM to determine which is the quietest. In a well-designed unit, the fan noise is no more noticeable than the noise of the HVAC system or an office copier.

4. Select an air cleaning technology that matches your needs.(Top)

Like any other machine, air cleaners are built differently by different manufacturers. Understanding how manufacturers use various technologies will help you decide which air cleaner best meets your requirements. Technical features that will be important to your decision include:

a. Servicing the air cleaner(Top)

Any air cleaner must be serviced periodically if it is to continue to provide satisfactory service. Servicing an air cleaner involves one of three procedures:

  • Replace the filter media (filter-type machines)
  • Clean the collection cells (electronic machines)
  • Replace the sorption beds (for machines so equipped)

The collection cells, filters or adsorbent beds should be easy to get to and remove.

Also, it is important to be candid about whether you'd rather replace filters or clean collection cells. Consider the following:

  • Filters are generally replaced less often than cells are cleaned. However, filter replacement is an ongoing cost
  • Collector cells make "Bug Zapper" noises if not cleaned
  • Filters clog up and stop the airflow if not replaced. Also, filters can recirculate odors if not changed regularly.

Remember, properly designed and installed air cleaners provide years of satisfactory service if properly serviced.

b. Energy efficiency(Top)

Generally, electronic air cleaners are more energy efficient than filter-type (media) air cleaners because they can use a lower powered fan. That's because the   electronic air cleaners offer less resistance to airflow than the media air cleaners. Look at the amperage ratings for the air cleaners you are comparing. If the CFM ratings are the same, the air cleaner with the lowest amperage rating is the most energy efficient.

c. Electronic air cleaner features(Top)

Electronic air cleaners work by passing the air through an electrical field that puts an electrical charge on the particles in the air. The air (along with the electrically- charged particles) then passes through a "collector" that is made of aluminum plates. These aluminum plates are also electrically charged. However, the charge on the collector plates is opposite to the charge on the particles. Remember how "opposites attract"? The electrically-charged particles are attracted to the collector plates and stick on the plates until the plates are cleaned.

Voltage doubler circuit(Top) - The electrical field part of the air cleaner (the "ionizer section") requires much higher voltage to be efficient than the collector section. The higher the volts per inch, the greater the efficiency of the air cleaner until the maximum voltage gradient of 20,000 volts per inch is reached. The level cannot be exceeded or arcing (snapping) will occur. In order to reach the highest efficiency possible while maintaining a compact collector section with a large collection area for easy and less frequent cell cleaning, a voltage doubler system (sometimes referred to as dual voltage) is employed. The high voltage is used for strong ionization, while the collection section voltage is dropped (roughly in half) in order to space collection plates closely together for more collection area (longer service life) without arcing thus achieving long service intervals, small package size, and high efficiency. Air cleaners with this voltage doubler feature will generally cost more; however the additional cost will be outweighed by less cleaning, a more compact unit, and greater efficiencies in most cases.

Electronic cell construction(Top) - The aluminum cell plates should be uniformly spaced and permanently held in place by some durable means. Ceramic high-voltage insulators hold up infinitely longer than plastic insulators. Cell plate area should be large enough for a reasonably long service life, yet compact enough for easy maintenance handling.

d. Media type air cleaner features(Top)

Media air cleaners work pretty much like the bag in your vacuum cleaner or air filter for your car; the air passes through and the dirt stays in the filter. Technical features that affect the performance of media air cleaners are listed below.

Media area(Top) - The media area for 1,000 CFM-range commercial air cleaners ranges from 28 sq. ft. to 130 sq. ft. Generally, the greater the media area, the greater the collection capacity. More media area means less airflow restriction, thus less noise and energy consumption. Perhaps most importantly, more media means the filters will last longer before becoming plugged with contaminants.

Media efficiency(Top) - Most 1,000 CFM-range commercial air cleaners are designed primarily for tobacco smoke removal applications. Tobacco smoke requires a media with very small pores in order to be captured because the particle size is so small. Therefore, an 85% or 95% filter is normally used. The percentage is based on the ASHRAE dust spot test. For extra hazardous or sensitive applications, a HEPA (high-efficiency particulate arresting) filter is used. The D.O.P. test is used to rate HEPA filters which are 99.97% efficient by definition.

5. Safety(Top)

It is very important that the air cleaner be designed and manufactured to the highest safety standards. Underwriters Laboratories Inc., founded in 1894, is a non-profit organization, established to maintain, and operate laboratories for the examination and testing of equipment to determine their relation to hazards to life and property. Underwriters Laboratories publishes safety standards specifically for air cleaning equipment.

Many state and local codes across the country require a formal recognition, from an approved laboratory such as Underwriters Laboratories (UL) or Inchcape Testing Services (ETL), that the air cleaner is safe to operate.

Before you buy, be certain that the air cleaner is recognized by UL or ETL.

6. Warranty(Top)

An air cleaner should be a long term investment, designed to offer many years of service. Read the warranty. Most reputable manufacturers offer a one to three year parts warranty. If a manufacturer offers a warranty that is too good to be true, such as a lifetime warranty, read it carefully. Find out how long they have been in business. Many times these lifetime warranties require you to buy replacement filters at the manufacturers recommended intervals to maintain the lifetime warranty. Read carefully.


There is no doubt that an investment in clean air is a wise and desirable step for your business. Employees will be happier and more productive, customers will be more comfortable and stay longer. The problem of the second hand smoke issue will be diminished as will the risk of legal liability and medical compensation claims.

There are many choices to be made regarding the system that will best fit your business. This guide is intended to provide general information about air cleaning options for your business. If you would like to further discuss your specific air quality issues with a trained professional, please contact us or use our information request forms found throughout our website by clicking the "information request" button on the upper left of most product pages.  We stand ready to assist you in achieving your goal of clean indoor air.

Thank you.

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