Dust Problems

So Where Does The Dust In My Home Come From

Wash Me

Dust in homes can come from many different sources.  Just living we generate dust.  Every time we move we generate dust from our clothing, skin cells, dirt carried in from outside, and dust that is driven air born from carpets, drapes, and furniture.  Pets generate a lot of dust and dirt particles.  They shed, they bring in dirt and dust from outside, and they groom themselves.  This can generate a lot of visible and invisible particles.  Another big source of dust is caused by duct leakage.  Any air that leaks out of ductwork when the fan is running must be made up by infiltration into the home.  Most of this air that is made up comes from the attic.  This Hot, Dusty, Damp, air comes in through the leaks around trim, at electrical connections, and light fixtures.  Recessed can lights if not properly sealed are extremely leaky and have large holes open directly or indirectly to the attic.  These leaks can cause a home to be extremely dusty.  We find that homes that were insulated with Cellulose insulation tend to be much dustier than homes insulated with fiberglass insulation.  The powder used in the blowing process for cellulose insulation drifts into the house for years and years.

Supply Air Grilles

The streaking around the supply air grilles from your air conditioner is a sign of air infusion around the grille.  As the air blows through the grille it actually creates a siphoning effect drawing air from the attic space around the grille through the cracks between the sheetrock and the duct.  This hot, humid, dusty, air comes into the space and deposits its dirt around the grille or on it.  It also brings in a lot of humidity and can actually cause the grille to sweat or the sheetrock around the grille to grow mold or mildew.  The solution to this problem is to take the grille off and caulk the gap between the duct and the sheetrock.


If your ceiling fans look like the one in these pictures then you probably have some major air leakage around the top of the fan where it connects to the ceiling.  The ceiling fan running draws air through the cracks from the attic and brings in this hot, humid, dusty attic air.  The spacing at the top of the fan needs to be sealed with caulk or foam fill to stop this air infiltration.

Do Room Model Air Purifiers Really Work

Some room model air purifiers do a pretty good job of catching the particles in the general area that they are placed.  The problem is that in order for the units to move enough air for them to do any good, they generally are too noisy to place in the room.  Units like the Sharper Image Ionic Breeze actually do very little to clean the air in a room.  Since they do not have a fan to circulate air, unless you are breathing right at the discharge side of the filter they do almost nothing to clean the air you breathe.  The better room model units will clean the large particles out of the air in a very limited area, generally about a 5 to 10 foot radius from the unit.  A whole house high efficiency air cleaner will catch the large particles and many of the small particles that circulate through it.  The air coming out of the supply vents will be cleaned air.  If you have a specific area in a room that you want extra air cleaning then utilize a good portable unit with a powerful enough fan to circulate some air in that area, if you can put up with the noise.

How Often Do I Need To Change My Filter


The definitive answer to this question is just before it starts restricting the airflow in the system.  This varies with the different types of filters and the home itself.  It does no good to replace a clean filter.  Since the media type filters actually get more efficient as they get dirty, they should be allowed to get dirty.  But not so dirty that they restrict the airflow.  If they are allowed to get too dirty the unit will starve for air, will actually suck the filter into the system, or could start sucking the dirt through the filter and into the system.  The standard one inch thick filters generally will need to be changed once a month or so.  The thicker filters can go 2 to 6 months, and the filters such as the April Aire can go a year or sometimes longer.  The key is to get into a routine of checking your filter and write the date on the filter when you change it.  The time has a tendency of getting away from us and it seems like we just changed it the other day when in fact it was three months ago.  This picture is of a badly impacted dirty cooling coil.  This system was running very inefficiently and could have been prevented by using a better filter.

What Other Problems Can I Have With My Filter


One of the keys to filtration is to make sure you are using the proper size filter and that it fits properly in the space.  A filter that does not fit properly can allow dirty unfiltered air to bypass the filter.  This can lead to dirty cooling coils and dirty units.  That leads to inefficient operation and higher electric bills.  Some filter frames do not hold the filter in place properly and allow the filter to rise up when the unit comes on and let the air bypass the filter.  A filter that is too small to allow the proper amount of air through it for the system can get restricted easily and will plug up and cause problems much faster.

Unsealed Return Air Cavity

If your filter is in a grille going into the cavity under your unit in a closet and the cavity is not sealed then you can be drawing air from the attic.  This is not a good thing.  It will get your system dirty fast and will cost you a lot on your cooling bills.  The picture here is of an unsealed return air cavity.  If you can look under your unit and see the studs and sheetrock like in this picture then you are drawing air in from the attic space above.  This type of cavity needs to be lined and sealed with ductboard to stop all the infiltration.  And if it has been running this way for very long then the blower and coil in the air conditioning unit probably need to be pulled and cleaned.