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Before you buy an air purifier, make sure you understand the various cleaning and
purifying technologies employed by the 5 different
types of air-purifiers and the
hybrid type purifiers.
Your first step is to identify what air quality issues are most prevalent in your home.
Then, you select the air purifier that best meet your needs. You've
the option to choose between a central unit or a portable (room) unit.
A central air purifier cleans all of the air in your home with just one unit. This
option is only available if you have a central heating/cooling unit that
circulate air in your home.
The central purifier is installed at your existing central air system. Before
the air leaves the central unit, it is drawn into the intake of the purifier and
cleaned before being circulated into your home again.
However, some tests showed that portable room units are generally more effective at
purifying the air, especially in single rooms. This may mean buying 1 or 2 portable units
for each room in your home.
The portable air purifiers cost between
$50 and $250, while larger or more efficient portables may cost up to $800. Central air
purifiers cleaners can cost $750 to $3000, depending on the size, the type
and efficiency of the device.
10 Tips to help you choose an air-purifier:
 What do you need?
Do you need an air purifier for allergen, pollen, gas control or viruses, etc?
For example, if your main goal is to clean the air of allergens, then a HEPA based
or the electronic (ionizer) air purifiers would be ideal. A gas phased filter would be
useless in this case. If your main concern is to remove bacteria and viruses, then
an UV light purifier would fit the bill nicely.
Efficiency
Efficiency can be measured by the particle size captured. - 0.3 microns or smaller
is an excellent "capture" size for any air purifier. Small particles from 0.3 to 5
microns includes allergens such as mold, bacteria, pet dander, and house dust mite.
A Hepa filter would easily trap particulates of this size and remove them from the air in your room.
However, more than 90% of all air borned particulates are smaller than
0.3 micron (examples includes: viruses, some bacteria and germs, some house dust mite
allergens, smoke, soot, fumes, and smog.) These particulates are known as
"lung penetrating particles" and are hazardous to your health.
So look for air filters or electronic (ionizers) air purifiers that can effectively
trap both large and small particulates.
Clean Air Delivery Rate
The Clean Air Delivery Rate (CADR) is a standard of measurement that describes the
number of cubic feet of clean air per minute an air cleaner can provide.
HEPA and Hepa-type air purifiers will usually list 3 CADR numbers - one for tobacco
smoke, one for pollen, and one for dust. A higher number means the unit is more
efficient in cleaning the air of that particular pollutant.
Another measurement to note is the CFM (Cubic Feet per minute).
This is a measurement of the amount of air (in cubic feet) that flows through the air
purifier per minute.
When choosing a HEPA filter, you must consider
the CFM number as well - because there is little benefit in buying a very good filter
if the amount of air filtered per minute is very small.
Example, 400 CFM Hepa air purifier is more powerful than one rated at 250 CFM.
This is
an important factor to note because the effective cleaning area of an air purifier
is calibrated at high fan speed. It is not practical to run your air purifier
at high speed at night in your bedroom.
For health reasons, a
typical 3-4 air changes per hour is required, and it's not possible to achive that
with low fan. So, you'll need a more powerful air purifier (in the 350-400 CFM
range) to accomplish that objective, in the 350 to 400 CFM range.
Noise Level
This is a personal preference because some people do not mind, or even welcome
background, while some people would go ballistic at the slightest fan noise.
You'll also need to consider where the air purifier unit will be placed - in
your bedroom? Study? Living room? The acceptable noise level in each of these rooms
will vary.
Another factor to consider is the size of your room. For example, if you're buying an
air purifier for your 300 square feet study, you may want to consider buying a bigger
unit. This is because the 500 square feet unit will do
an excellent job in a 200 square feet room at low or medium speed with
a lower noise level.
So, before you purchase your unit, make sure you get a demonstration of
the air purifier model to determine noise levels, even at slow speeds.
Pre-Filters
Many air purifiers comes with a pre-filters. Their main function is to
remove the larger particulates from the air to protect the more expensive filters such as
the HEPA filter and activated carbon (for the gas phased air purifier) from being
used up prematurely.
Most pre-filters are designed to remove particulates between 5-10 microns and larger.
A large gas phased purifier with 10 pounds of activated carbon will be quickly saturated
if there is no pre-filter in the unit. Likewise, using an expensive
HEPA filter to remove large particles (e.g bigger than 1 micron) is sheer waste of money.
Running Cost
An "expensive" air purifier may end up being cheaper than an inexpensive unit
in the long run. This is because many people tend to overlook the annual running cost
of the unit. An air purifier that costs $300 to $500 can end up costing from as little
as $50 a year to maintain or as much as $150 a year. The bulk of the running cost
goes into replacing filters and electricity to run them.
You need figure out how often the filters need to be changed and how much they cost.
Some air purifiers have expensive filters, but they usually last longer before requiring
a change.
If you've a hybrid air purifier, it is helpful if you can change individual filters in
your unit instead of one expensive combo filter.
For example, if your air purifier is a
Hepa + activated carbon bas filter, it is very rare that you will need to change both
filters at the same time.
Usually, the gas filter will need to be changed more often.
If yours is a combo filter, then you'll have to change the entire filter which
is an uncessary expense.
Note: the quoted filter change intervals will vary depending on how often the
unit is run and the pollution level of its environment.
Ease of Maintenance
Some air purifiers come with a filter change indicator light. This is more accurate
than relying on one's senses (e.g. smelling odors to determine if the
gas filter needs to be changed). A filter change indicator will remove all the guesswork
in maintaining your air purifier in optimum running condition without clogged filters.
And, you won't be prematurely changing your filters which is an unnecessary expense.
A well-constructed air purifier will have individual filters (e.g pre-filter, gas filter,
Hepa filter) which can be easily changed without requiring a professional service.
Also, check the air purifier manual - a good manual will explain the filters in the unit,
how to set it up, whether any assembly is required, has troubleshooting tips
and gives you maintenance information. A poorly written manual can be very frustrating!
Electronic Air purifiers
The main advantages of electronic air purifiers (e.g. electrostatic precipitators and
negative ionizers) are there are no costly filters to replace. They are also quieter than Hepa
filters since they don't have a fan. The electricity bill will be lower as well.
In addition, there's the additional health benefits of negative ions being
released in the air
However, as the metal plates become dirty, its cleaning efficiency will drop,
so it will require regular cleaning.
Reliability and Warranty
You should not just look at the retail price. If you purchase a cheap air purifier
with a short warranty, you may find yourself replacing the unit very soon. I've personally
experienced this. You would have been better off purchasing a more expensive good quality
air with a long warranty. The best warranties are those offering five years on the main fan and motor parts.
A reliable air purifier should not have any problems with the motor,
fan, electrical components and controls. The rest of the air purifier consists of the
filters, which need periodically cleaning or replacement.
Quality control is important and any information you can glean about the reliability and
breakdown rates of the air purifier is recommended.
After Sales Support
Finally, buy from a reputable manufacturer or retailer. You would want to buy
from someone who would be able to work with you and service your your air purifier unit.
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