Air filters
protect your hvac system. When we work in a dirty environment, we usually wear
a mask to protect our lungs. The filters in your hvac system have the same
function. The filter in your hvac system has two main functions. First it helps
to improve your home's indoor air quality.
This can improve
the health of your family. According to the U.S. EPA, the air inside your home
can be 2 to 5 times worse than the air outside.
The second thing
they do is to keep your hvac system clean. If the dirt gets through the filter
it can clog your furnace's secondary heat exchanger. This can happen if you
have a condensing type furnace. If you don't have a condensing type furnace,
the dirt will collect on your ac unit's evaporator coil.
Either way, this
restricts air flow. This in turn can cause higher temperatures during heating
system operation and premature failure of parts. During cooling operation, the
operating efficiency will be reduced, your electric bills will go up, and it
will cause more wear and tear on system parts.
The filter is
usually located in one of the following places:
1. In a grille
in your wall or ceiling. These are commonly called return air filter grilles.
2. In a slot on
the side, bottom or top of your furnace. It depends on the style of furnace you
have.
3. Inside the
blower compartment of the furnace. This is common on older furnaces. Most
manufacturers do not recommend this on new furnaces.
Air filters have
a standard rating. This rating, minimum efficiency reporting value (MERV), is a
number from 1-16. You don't have to know all the technical jargon. Simply put,
as the number goes up the unit will stop more and smaller particles.
If you decide to
replace your existing air filter with one of a higher MERV rating, you should
check to make sure you have sufficient airflow after you replace it. This is
done by checking the temperature rise in the heating mode and the temperature
drop in the cooling mode.
Many hvac units
come with a washable type of filter. These will usually be made of foam. These
have a merv rating of 1 to 4.
You can also use
a disposable type which is normally made of fiberglass. These have a merv
rating of 1 to 4.
Usually you can
hold those types of filters up and see through them. If that is the case, you
know they are not doing their job.
Another
disposable type is the pleated filter. These have a merv rating of 5 to 8.
These products have more surface area to catch the dirt. They also distribute
the airflow more evenly. This means the fan is less likely to pull the dirt
through the filter. This is the type of filter that we recommend for most
applications. They are the best value in terms of price for the filter and
keeping your hvac system clean.
Air filters with
the higher MERV ratings are sometimes called allergy filters.
Some are made of
advanced materials which set up a static electrical charge. They are called
electrostatic filters and are able to capture much smaller particles.
Some come with
an antimicrobial treatment. This prevents organisms from living on the filter
when they are trapped.
Using the right
air filter is only half of the answer though. If it is not replaced often
enough, your hvac system operating efficiency will go down. This will cost you
on your utility bills as well as wear and tear on the hvac unit.
Most people,
even those in the hvac industry, don't change their filter as often as they
should. It is usually out of sight and out of mind.
Most hvac
service companies offer service contracts where they change your filter. These
contracts can be expensive when you consider you can do it yourself.
There are other
options if you have special needs such as allergies. The ultimate filter is
called a high efficiency particulate air filter(HEPA). These remove virtually
everything but the replacement elements can be expensive unless you shop
around.
You should also
keep in mind that if the filter is a part of the central hvac system and the
fan is not continuously running, then most of the time the filter will not be
doing anything.
