Is Cleaning Your Air Ducts Necessary?

We had our furnace replaced five years ago, and the serviceman suggested we have the air ducts cleaned out. Up until that time, we had never even heard of air duct cleaning, but it made perfect sense. After 120 years of coal heat coursing through the duct work, I was sure that the duct work was pretty grimy. Watching dust spill out the registers certainly indicated that a cleaning was necessary.

The service company we called did an excellent job of knocking the accumulated dust out of the vents. Just like we had thought, greasy coal residue had accumulated in the air ducts, and had attracted lots of dust and other particles. Once the ducts had been vacuumed, the air coming from the vents was definitely cleaner.

What is air duct cleaning?

These days, people are more aware of indoor pollution, and many companies are now marketing products and services to improve the quality of the air in the home. Air duct cleaning is just another service that cleans not only the duct work, but all the components of an air conditioning and furnace systems as well.

The service men who cleaned our duct work pushed a lot of extra services. They suggested we sign up for a yearly maintenance plan to prevent the buildup of dust, and even recommended that we apply a sealant to the inside of our duct work to prevent coal dust from entering our home. They discussed things such as chemical biocides and potential mold growth. They were a little too pushy for our liking, and we politely declined additional services. Since that time, we’ve learned a few things about air duct cleaning.

So how necessary is it?

The Environmental Protection Agency (EPA) suggests that if no one in the home suffers from allergies or unexplained illnesses, if the duct work looks clean with a visual inspection and there are no signs of mold or accumulated dust, then a duct cleaning probably isn’t necessary. They indicated that air duct cleaning has not been shown to provide health benefits or prevent illness. As far as the chemical biocides and sealants, these have not yet been fully researched.

Dust will naturally accumulate on a grate or near a vent as the air rushes into a room. Removing the grate and vacuuming the dust with your household vacuum cleaner is all that’s necessary. And, what about the dust collecting on the inside of the ducting? We reasoned that the dust already sticking to the ductwork will stay there, so there’s no reason to encapsulate it with a sealant. This is precisely the logic that the EPA offers. They also mentioned that dust enters the home in many other ways besides the ductwork, such as windows, doors, and on our feet. Just moving around a room can stir up dust!

The EPA does recommends cleaning the ductwork in certain circumstances. Air ducts should be cleaned if there is an infestation of rodents, insects, or other pests in your duct work; visible signs of mold; or, large amounts of accumulated dust, particles, and other debris in the duct work.

Whether you decide to have your air ducts cleaned is up to you. If you feel the ducts must be cleaned, the EPA suggests you get several bids, and ask lots of questions. They do caution that ductwork sometimes can contain a substance that looks like mold, but isn’t. Mold can only be tested by a reputable laboratory, and not by a visual inspection.

Preventative measures

There are also some preventative measures you can take to prevent dust and water from contaminating your ductwork in the first place.

To prevent dirt from entering your furnace system, use the highest efficiency filter recommended for your system. Change filters regularly, and watch for gaps between the filter and the filter holder. Seal your vents and air intake when doing construction in the house, vacuum your home regularly, and have your Air Conditioning & Heating serviceman clean the coils and drain pans, with your regular service.

To control moisture, you should repair any water leaks and remove standing water, make sure that the drain pan beneath the cooling coils slopes to the drain, and keep your humidifier and air conditioning unit properly serviced. If visible duct insulation is wet or moldy, have it removed and replaced by a reputable service company.

The EPA puts out a wonderful on-line publication that addresses air duct cleaning and consumer protection. It also lists what to look for in a reputable air duct cleaner. The publication can be found at, and tells you everything you’ll need to know to make an informed decision.

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