Updated: November 2017

Air Duct Cleaning

There has been a recent proliferation of commercials for indoor residential air cleaners and air filters, promising to remove dust, pollen, allergans, and everything else from the air you breathe all day. On top of that, a lot of companies that offer HVAC (heating, ventilation, air conditioning) services have also found a new source of revenue by convincing people to have the air duct of their heating and cooling system cleaned, promising to remove dirt and dust, mold, and any other residue that is filling your air ducts and being blown into your home. There is however, little research or evidence that indicates that cleaning air ducts actually improves air quality in a home, so before shelling out $500 or $1000 to have your air ducts cleaned, read on below to find out about the components of your HVAC system, how your furnace and AC move air through your home, and what the major causes of indoor home pollutants are.

How does your heating and air conditioning work?

The first step is to understand how your heating system and air conditioning work. The typical residential home has a furnace (gas or oil fired, usually in the garage or basement -- homes with 2 zones will have a second furnace unit, usually in the attic) that contains a heat exchanger and blower, and is connected to air ducts in 2 directions - one main set of trunks and supply line that send the hot or cold air from the furnace out into the rooms of the house, and another return duct that circulates returning air from the rooms back into the system, creating a constant flow of air. Return registers in your home will simply look like grills on the ceiling or walls - you will never feel air coming out of these, but air is going into them and being fed into the return air duct down in the furnace. The return air is fed through a filter to remove any particulate pollutants (or as much as your filter can handle - cleaning and replacing air filters regularly is more important for keeping your air clean), then it goes through the heat exchanger and gets blown back out into the supply trunk line and ducts and out through the supply registers you see around your house on the floor, walls, or ceiling - these supply registers are the ones that you will feel the hot or cold air spilling out of.

What do air duct cleaners do? Do air ducts need to be cleaned?

So behind the scenes of this cooling and heating system lies all the duct work. The duct work consists of the supply main trunk and then the branching off supply branches. The main trunk looks like a long aluminum rectangled tube, often wrapped in insulation of some kind. The smaller branch supplies are normally flexible metal tubes, looking much like the dryer exhaust hose you hook up to the back of your dryer. So how does air duct cleaning work? These tubes and ducts are what is being cleaned when someone cleans your air ducts - they remove all the register covers and insert vacuum scrubbing brush units down (or up) into the ductwork, cleaning and removing buildup as they go. They will also clean around the furnace unit and the filter areas removing whatever they find. How long does it take to clean the air ducts? - usually about 2-4 hours for a home with a single air handler. Most companies that offer air duct cleaning services promote themselves as something good for your health and the health of your family. Cleaner air is supposed to help avoid respiratory problems and diseases, like allergies and asthma. They also suggest you should clean your air ducts every 3-5 years. However, it can be equally argued that anything stuck in the ducts is not blowing out into the house anyways, and anything that does go through the ducts should also go through the filter.

According to the EPA, if you don't see a lot of mold or dust when you look into your registers, and no one in the household is suffering from allergies or unxeplained illnesses, you may be able to forego air duct cleaning. They even say that cooking, smoking, cleaning, and simply moving around your house likely causes more air pollutants than does dirty duct systems. From the EPA website: "If no one in your household suffers from allergies or unexplained symptoms or illnesses and if, after a visual inspection of the inside of the ducts, you see no indication that your air ducts are contaminated with large deposits of dust or mold (no musty odor or visible mold growth), having your air ducts cleaned is probably unnecessary. It is normal for the return registers to get dusty as dust-laden air is pulled through the grate. This does not indicate that your air ducts are contaminated with heavy deposits of dust or debris; the registers can be easily vacuumed or removed and cleaned."

How much does air duct cleaning cost?

Air duct cleaning usually costs about $400-$800 for an average size home - a home with 2 zones may cost $1000 or slightly more. If you are intent on getting your air ducts and ventilation system cleaned, get several quotes from reliable sources, preferably from references from friends or neighbors who have had the service done. Most services will also try to sell you additional products and services like chemical treatments or anti-bacterial or microbial sprays. Unless you have a serious known mold problem, you probably don't need any of these "extras" that they will want you to buy.