There are a few signs to watch out for to catch them in time. For one, if your breathing starts acting up or you start coughing or sneezing, there is probably some buildup in the vents. If you suspect mold or start hearing scritches in your pipes, there's a good chance you have enough dirt for bigger problems to unfold. You should clean your ducts and vents every few months just to be safe. This is even more important and should be done more frequently if you live in a very humid or dusty climate.
If you or someone in your family suffers from asthma or allergies, you may be considering getting your home’s heating and cooling ducts cleaned. But even if you have no special health concerns, cleaning your ducts may appeal to you at an intuitive level. After all, if your ducts are clean, all that air flowing out of your vents should come out clean, too, right?

I had someone out to clean my ducts last weekend. He took a blue bag up in my attic. He came back down in just a few minutes and said I had mold and he even showed me a picture of something saying it was mold but I couldn’t really tell. I refused his service to take care of the mold. He went back up in the attic for a little while and then came down. I never heard any sounds that he was actually up there doing anything. How do I know if he actually cleaned the air ducts?
On the other hand, if family members are experiencing unusual or unexplained symptoms or illnesses that you think might be related to your home environment, you should discuss the situation with your doctor. EPA has published the following publications for guidance on identifying possible indoor air quality problems and ways to prevent or fix them.
Recent Review: Their crew arrived promptly at 7:00 am. Carlos explained what each crew member would be doing. They increased the insulation in my attic. They also discovered that the ducts had been attached to the vents with plain duct tape. The duct tape had become gooey due to heat and had slipped off the vents in many places. This allowed out side air and dust to enter, spreading dust out of the vents. It also allowed cooled air to escape into the attic. The corrected all of the duct work connections. Jeff came to check the work upon completion. He ran tests to verify that the work had been done correctly, and he replaced all of the "regular" light bulbs with cal bulbs. All of the work was done quickly and neatly.
Definitely would recommend. I just bought a house in the Hyde Park area. It is an older house, but I could tell just by looking at the vents that they had not been cleaned in years. I was having issues with my breathing, so I decided to have them cleaned. You have to schedule pretty far out in advance, but it is because they are very busy. They gave me a time window of 8-11 and showed up right in the middle of that window. I opted for the full cleaning and sanitizing because my vents were that bad. The two guys that cleaned my vents did a great job. He recorded the vents before and after and I could not believe the results. He also showed me what had been caught by my filter and sucked up by the vacuum. Would highly recommend to anyone purchasing a home to have this done.
The Canada Mortgage and Housing Corporation (CMHC), a government agency, conducted a study in the 1990s to investigate two claims: Duct cleaning makes indoor air healthier; and it reduces energy costs by improving airflow. After testing 33 homes in Montreal before and after duct cleaning, the study found that there was no significant improvement in air quality and that duct cleaning alone did not improve airflow or energy efficiency. In some cases, measured particle levels actually increased immediately after a cleaning. In other cases, particle levels decreased immediately after cleaning but returned to previous levels within weeks.
Their crew arrived promptly at 7:00 am. Carlos explained what each crew member would be doing. They increased the insulation in my attic. They also discovered that the ducts had been attached to the vents with plain duct tape. The duct tape had become gooey due to heat and had slipped off the vents in many places. This allowed out side air and dust to enter, spreading dust out of the vents. It also allowed cooled air to escape into the attic. The corrected all of the duct work connections. Jeff came to check the work upon completion. He ran tests to verify that the work had been done correctly, and he replaced all of the "regular" light bulbs with cal bulbs. All of the work was done quickly and neatly.
I’m having my duct work cleaned this Saturday. Have a coupon for $49 through Amazon. Job normally $249. Had my basement remodeled about 18 months ago. The contractors were very thorough at blocking the vents, as far as I can tell. The offer is for HVAC and dryer vent cleaning. My house is 11 years old. I figured, $49 is not much. I appreciate your tips on not getting talked into any additional service, not to use solvents to clean, the certification information and before and after pictures. Very useful and I’ll be sure that all I spend is the $49 for the voucher.

Manufacturers of products marketed to coat and encapsulate duct surfaces claim that these sealants prevent dust and dirt particles inside air ducts from being released into the air. As with biocides, a sealant is often applied by spraying it into the operating duct system. Laboratory tests indicate that materials introduced in this manner tend not to completely coat the duct surface. Application of sealants may also affect the acoustical (noise) and fire retarding characteristics of fiber glass lined or constructed ducts and may invalidate the manufacturer's warranty.
Recent Review: Their crew arrived promptly at 7:00 am. Carlos explained what each crew member would be doing. They increased the insulation in my attic. They also discovered that the ducts had been attached to the vents with plain duct tape. The duct tape had become gooey due to heat and had slipped off the vents in many places. This allowed out side air and dust to enter, spreading dust out of the vents. It also allowed cooled air to escape into the attic. The corrected all of the duct work connections. Jeff came to check the work upon completion. He ran tests to verify that the work had been done correctly, and he replaced all of the "regular" light bulbs with cal bulbs. All of the work was done quickly and neatly.
We bought a short sale home buit in 1987.  The home is gross to say the least. I called last week to set the appt. up once I knew we had a close date. They called to say they were running a bit late, which happens with this type of work. They did great work, cleaned up after themselves, very nice men, cleaned all the vents,fans inside and out. I will feel much better bringing my family into a clean home now.
Washington Consumers’ Checkbook magazine and Checkbook.org is a nonprofit organization with a mission to help consumers get the best service and lowest prices. We are supported by consumers and take no money from the service providers we evaluate. You can access Checkbook’s ratings of local HVAC companies free of charge until Feb. 28 at Checkbook.org/washingtonpost/ducts.
Chemical biocides are regulated by EPA under Federal pesticide law. A product must be registered by EPA for a specific use before it can be legally used for that purpose. The specific use(s) must appear on the pesticide (e.g., biocide) label, along with other important information. It is a violation of federal law to use a pesticide product in any manner inconsistent with the label directions.

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.
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