Indoor Air
Quality (IAQ) is a current buzzword in the Heating, Ventilation and Air
Conditioning (HVAC) Industry.
We hear about Legionnaire's disease
outbreaks traced to the air conditioning system. Buildings are highlighted on
the news as making their tenants sick and it's referred to as sick building
syndrome. Individual homes are linked to increases in allergies and asthma. Can
it happen to your home and what can you do to prevent it or correct it if you
are already the proud owner of a house that is making you sick?
The
ever-increasing cases of sick building syndrome are due to the way houses and
buildings are constructed to conserve energy. Stop air movement in and out of
the home and you reduce the energy required to heat and cool the house. After
you seal the house up, central cooling and heating systems maintain livable
temperatures and humidity levels within the home by re-circulation of the same
air and pollutants day after day. Dust, bacteria, viruses, mold, fungus, mildew
and gases circulate through the building. The dust can come from skin, hair,
clothes or just come off shoes when we walk in and out. The mildew, fungus and
molds can come in along with the dust or we can grow our own in the HVAC system.
The gases are volatile organic compounds that are given off by dyes, paints,
varnishes and adhesives used in modern building materials. The best example of
gases is that burning eye sensation we get after new carpet is installed. So
let's look at Filtering The Dust, Killing the Mildew, Molds, Fungus, Bacteria,
and Viruses and Ventilating the Volatile Gases in an attempt to breathe easier.
Filtering the Air We Breathe
The most important step in
filter improvement is to make sure that all the air that goes through the
electric air handler or gas furnace is filtered. If your HVAC system is pulling
air through cracks in the duct system or return air chase, it pulls the
contaminates along with it. Have your service technician check to verify that
all the return air to a system is pulled through the filter system. This is a
good time for your service technician to verify that the filter system is sized
large enough for proper operation of the system.
Filters come in
different efficiencies that are measured in the percentage of arrestance of
particles. Simply stated, what amount and size of particles do they stop? The
higher the percentage, the smaller the particle the filter will stop. The other
factor that must be considered is the resistance to air flow, or will this super
filter let enough air through to allow my system to function properly?
Fiberglass
- these are the most inexpensive filters that you can buy. Most people refer
to them as the filter you can see through. They stop 15% of the largest
particles in the air. Replace monthly.
Pleated Paper - these
filters look like a paper version of drapery pleats and stop up to 45% of the
particles in the air. This type filter is the easiest upgrade for the money
spent. These filters come in the same size as a fiberglass filter and are
available at most hardware/home improvement stores. This type of filter gives
the greatest degree of improvement for the money spent. Replace every 1 to 3
months.
Media Filter - these filters are up to 4 inches thick
and come in limited sizes, though the size selection is increasing. Rated at 90%
to 95% efficiency, these filters are changed 2 to 3 times a year. Media filters
require a special frame to be mounted in the wall or mounted directly to the
furnace or air handler. There are some media filters that come with special
adapters that allow them to be mounted in a standard filter frame that has 4
inches of clearance behind it.
Electrostatic filters - As an
upgrade to Fiberglass filters, these are made up of layers of synthetic material
that generate an electrical charge to attract dust particles. Electrostatic
filters come with guarantees from five years to life. There have been problems
due to high restriction of airflow across the filter. This reduction of airflow
can greatly reduce the system capacity and efficiency. A new generation of these
filters is now coming to market that promises less restriction to airflow. Clean
at intervals of between 1 to 4 weeks.
Electronic Air Filters -
this is the premiere filter system on the market today. An electrostatic grid is
powered when the AC or heat comes on and attracts particles to it. The grid is
cleaned as needed with a water hose or in the dishwasher. This is the most
efficient filter system available. This type of filter normally fits the same
space as a Fiberglass filter, but does require modification to the ductwork and
wiring to be installed in your air conditioning system.
Some
contractors pre-filter either the media or the electronic filter with a pleated
paper filter and move their cleaning or replacement to a yearly schedule. The
main idea regardless of the type of filter you choose is to filter all the air
you circulate in your house and to remove as much dust and other particles as
needed to breathe comfortably. One benefit of the high efficiency filters is a
reduction in the need to dust the furniture. Ask your Estes service tech which
filter is best for you.
Killing the Mildew, Molds, Fungus,
Bacteria, and Viruses
One of the ways our air conditioning system keeps
us comfortable is by removing the water vapor (humidity) from the air. As the AC
system condenses moisture from the air, a drain is supposed to take this
moisture out of the system. What really happens is that some of this water
splashes on the interior insulation and some of it is left standing in the
bottom of the pan that is not designed or installed to get it completely out of
the system. So, now, we have moisture ready to support the growth of assorted
micro-organisms that will cause a variety of respiratory problems.
The
simplest treatment is to keep drain lines clear and to have a positive drainage
on the coil.
Pan tablets and drain pads are available that release
chemicals into the condensed water and kills the pathogens. These tablets or
pads must be physically placed in the evaporator drain pan on a 1 to 6 month
schedule.
UV lights are the newest tool to be used to improve indoor
air quality. Similar to the lights that barbers, dentists, and doctors use to
sterilize their instruments, these lights are designed to not only kill what's
growing in the drain pan, but also what is growing on the coil surface or on the
interior insulation. These lights will kill the source of numerous allergens
that people did not know existed. The light shines on the inside of the AC, in
front of the coil, 24 hours a day. Even if a new bulb is required every year,
the UV light combined with a good filter system will greatly improve the quality
of air in either a home or business.
Even older air conditioning units
can usually be retrofitted with UV lights.
Ventilating Gases
As
home construction has produced tighter homes, reaction to gases released from
building materials has increased. The trick is to bring in fresh air without
having to heat, cool or dehumidify it. This can be accomplished in several ways
and must be routed through the filter system.
Heat Exchangers
- exhaust air is pushed through a tubular heat exchanger as fresh air is pulled
in around the outside of the tubes, allowing the air to exchange heat. The
exchanger does not bring hot air down to room temperature or cold air up to room
temperature but does reduce the temperature difference and the energy needed to
bring it to the desired temperature. This solution guarantees fresh air will
enter the house and stale air will be exhausted along with the toxic gases.
Desiccant
Wheels - similar to heat exchangers but use a rotating wheel to remove
humidity from the incoming air and add it to the exhausted air. Desiccant wheels
will be used were humidity is the greater problem; heat exchangers will be used
where low winter temperatures are the greatest problem.
Conclusion
In
conclusion, these various methods to improve air quality can be built into a new
or replacement system at the time of installation to achieve the best-cost
savings. Any of these improvements can also be added to an existing system. You
may find relief with just improving your filter system or with a filter and an
ultraviolet light. However you mix and match to achieve breathable air, Swift
Air Mechanical can provide you with the needed expertise and quality equipment
to accomplish the job.
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