Like regularly changing the batteries in you smoke detector, a periodic home
inspection of you heating and cooling system is always a good idea.
Aesthetically changing the vents, registers and grilles because of room
dynamics is one thing, but watch out for the obvious. Register or "damper"
failure due to dust, grit or rust should certainly be looked into.
I hope the information and links below will help you understand and be aware
of the "ins and outs" of your heating and cooling system.
A Typical Residential Heating and Cooling System
You should consider having the air ducts in your home cleaned if:
There is substantial visible mold growth inside hard surface (e.g., sheet
metal) ducts or on other components of your heating and cooling system. There
are several important points to understand concerning mold detection in
heating and cooling systems:
- Many sections of your heating and cooling system may not be accessible
for a visible inspection, so ask the service provider to show you any mold
they say exists.
- You should be aware that although a substance may look like mold, a
positive determination of whether it is mold or not can be made only by an
expert and may require laboratory analysis for final confirmation. For about
$50, some microbiology laboratories can tell you whether a sample sent to
them on a clear strip of sticky household tape is mold or simply a substance
that resembles it.
- If you have insulated air ducts and the insulation gets wet or moldy it
cannot be effectively cleaned and should be removed and replaced.
- If the conditions causing the mold growth in the first place are not
corrected, mold growth will recur.
Ducts are infested with vermin, e.g. (rodents or insects); or
Ducts are clogged with excessive amounts of dust and debris and/or
particles are actually released into the home from your supply registers.
Other Important Considerations...
Duct cleaning has never been shown to actually prevent health
problems. Neither do studies conclusively demonstrate that particle (e.g., dust)
levels in homes increase because of dirty air ducts or go down after cleaning.
This is because much of the dirt that may accumulate inside air ducts adheres to
duct surfaces and does not necessarily enter the living space. It is important
to keep in mind that dirty air ducts are only one of many possible sources of
particles that are present in homes. Pollutants that enter the home both from
outdoors and indoor activities such as cooking, cleaning, smoking, or just
moving around can cause greater exposure to contaminants than dirty air ducts.
Moreover, there is no evidence that a light amount of household dust or other
particulate matter in air ducts poses any risk to health.
EPA does not recommend that air ducts be cleaned except on an
as-needed basis because of the continuing uncertainty about the benefits of duct
cleaning under most circumstances. If a service provider or advertiser asserts
that EPA recommends routine duct cleaning or makes claims about its health
benefits, you should notify EPA by writing to the address listed at the end of
this guidance. EPA does, however, recommend that if you have a fuel burning
furnace, stove, or fireplace, they be inspected for proper functioning and
serviced before each heating season to protect against carbon monoxide
poisoning. Some research also suggests that cleaning dirty cooling coils, fans
and heat exchangers can improve the efficiency of heating and cooling systems.
However, little evidence exists to indicate that simply cleaning the duct system
will increase your system's efficiency.
If you think duct cleaning might be a good idea for your home, but you are
not sure, talk to a professional. The company that services your heating and
cooling system may be a good source of advice. You may also want to contact
professional duct cleaning service providers and ask them about the services
they provide. Remember, they are trying to sell you a service, so ask questions
and insist on complete and knowledgeable answers.
||Learn as much as possible about air duct cleaning before
you decide to have your ducts cleaned by reading this guidance and
contacting the sources of information provided.
||Consider other possible sources of indoor
air pollution first if you suspect an indoor air quality problem exists in
||Have your air ducts cleaned if they are visibly
contaminated with substantial mold growth, pests or vermin, or are clogged
with substantial deposits of dust or debris.
||Ask the service provider to show you any mold or other
biological contamination they say exists. Get laboratory confirmation of
mold growth or decide to rely on your own judgment and common sense in
evaluating apparent mold growth.
||Get estimates from at least three service providers.
||Ask the service provider whether he/she holds any relevant
state licenses. As of 1996, the following states require air duct cleaners
to hold special licenses: Arizona, Arkansas, California, Florida, Georgia,
Michigan and Texas. Other states may also require licenses.
||Insist that the service provider give you knowledgeable and
complete answers to your questions.
||Find out whether your ducts are made of sheet metal, flex
duct, or constructed of fiber glass duct board or lined with fiber glass
since the methods of cleaning vary depending on duct type. Remember, a
combination of these elements may be present.
||Permit the application of biocides in your ducts only if
necessary to control mold growth and only after assuring yourself that the
product will be applied strictly according to label directions. As a
precaution, you and your pets should leave the premises during application.
||Do not permit the use of sealants except under unusual
circumstances where other alternatives are not feasible.
||Make sure the service provider follows the National Air
Duct Cleaning Association's (NADCA) standards and, if the ducts are
constructed of flex duct, duct board, or lined with fiber glass, the
guidelines of the North American Insulation Manufacturers Association (NAIMA).
||Commit to a preventive maintenance program of yearly
inspections of your heating and cooling system, regular filter changes, and
steps to prevent moisture contamination.