Moisture can enter the duct system through leaks or if the system has been improperly installed or serviced. Research suggests that condensation (which occurs when a surface temperature is lower than the dew point temperature of the surrounding air) on or near cooling coils of air conditioning units is a major factor in moisture contamination of the system. The presence of condensation or high relative humidity is an important indicator of the potential for mold growth on any type of duct. Controlling moisture can often be difficult, but here are some steps you can take:
In addition, the service provider may propose applying chemical biocides, designed to kill microbiological contaminants, to the inside of the duct work and to other system components. Some service providers may also suggest applying chemical treatments (sealants or other encapsulants) to encapsulate or cover the inside surfaces of the air ducts and equipment housings because they believe it will control mold growth or prevent the release of dirt particles or fibers from ducts. These practices have yet to be fully researched and you should be fully informed before deciding to permit the use of biocides or chemical treatments in your air ducts. They should only be applied, if at all, after the system has been properly cleaned of all visible dust or debris.
I spent a lot of time reading all these posts and frankly I can’t believe the way some people think. 1. If there is dust and dirt of any kind in my HVAC system I want it out, the mentality that it can stay there and it’s fine is fulish as the system turns on and off microscopic particulates will move in and out of your living space and you will definitely breath them in. The air quality of your home or office will only be as clean as the system that produces it. We don’t not clean things simply because we can’t see them, it’s what we can’t see that can do the most harm. Dust will build up in a system fairly quickly and will get damp at times allowing mold to grow and mold releases spores without any movement as part of its defense meconisam so don’t tell me that when your system turns on it won’t blow the spores out into the living spaces of your home. A build up of dust will cause failures to your system over time, equipment that works harder to do its job will run hotter with more strain and this will lead to brake downs and until then the system will run less efficient then it should. The system was engineered to move a certain volume of air through a specific duct size, when that duct size starts to become narowed down with dust build up your system has to work harder to move that air this is why you will end up with a loss of efficiency and eventually breakdowns or failures. I have seen systems develop a significant amount of dust build up in as little as two years, just look at how fast the filter gets clogged up and it isn’t all that hard to believe. As for all the scams that are out there they hurt the industry because people can’t decipher between them and the legitimate companies, BBB is helpful. Recommendations from HVAC contractors will be a good resource and a good company will provide a written estimate with a complete brake down of what they are going to do and why, most of which is comen sence once they explain it to you, then if you spend about 5 minutes watching them once they are set up you can see they are doing what they said they would do and let’s get real would you do a job that should take approx 3 hours per system for $29/$39/59 or something close to that, if you think you are going to get a good job from a comp that has to make money at that price you shouldn’t be mad at anyone but your self for trying to get quality work at a scam price. If it’s done right it will be very beneficial and depending on the size of your system and where you are in the world it’s going to cost you approx $300 to $600 per system large and or older systems may cost even more. Remember a quality job isn’t wasting money but a lousy job is, even if it’s only $29. I’d rather spend $600 on a quality job then $29 on a lousy job!! Good luck..
I live in Port Orange, FL. I purchased a double wide mobile home and was saddened to learn that the previous owners were HEAVY smokers! They did a good job “hiding” the smoke smell the day we viewed this place. I did not have a home inspection done unfortunately. My question is: can duct cleaning remove the smoke smell from this place. The ceilings have been treated with Kilz and paint. I personally scrubbed down every wall, floor or surface. I also purchased a ODORFREE OZONE machine. It seemed to remove the odor for a short period of time but my friends are again complaining about the “smoke” odor in my home. The Ozone machine was $400 and I’m terribly upset that it didn’t clean the air as was promised.
EPA does not recommend that air ducts be cleaned except on an as-needed basis because of the continuing uncertainty about the benefits of duct cleaning under most circumstances. EPA does, however, recommend that if you have a fuel burning furnace, stove, or fireplace, they be inspected for proper functioning and serviced before each heating season to protect against carbon monoxide poisoning. Some research also suggests that cleaning dirty cooling coils, fans and heat exchangers can improve the efficiency of heating and cooling systems. However, little evidence exists to indicate that simply cleaning the duct system will increase your system's efficiency.

Well, I had the cleaning done. The handler is definitely much quieter. It was explained to me that with the coils clean, the condensation will be able to sweat off instead of sticking to the dust and dirt, therefore the humidity (lots of humidity in florida) will be removed better. I feel as if it was worth it, but, I will definitely change that filter every 3 weeks or so from now on. I don’t want to pay that cost again.
Vinick calls air duct cleaning an essential part of home maintenance, akin to mopping and vacuuming. "It’s like changing the oil in your car,” he says. “If you don’t change the oil, you’re going to have a problem. When your components are loaded up with debris, the system has to work harder. When you remove that debris, you get energy consumption savings.”
I turned on the AC when he was finished and immediately saw black fuzz balls the size of marbles come out of several of the registers. He said that was expected since everything was shaken up. So much for describing the service as cleaning. I paid him and sent him on his way. I cannot imagine that this type of service is worthwhile in anything but a new house. Apparently in old houses such as mine I can expect that using a whole house humidifier in the winter followed by a great AC can loosen the soot. Maybe this is to be expected for the first few weeks of summer each year. I now have lined the inside of the registers with cheesecloth to catch the fuzz. I’ll see if it stops after a couple of weeks.
The fact is if they are dirty why not clean them. As for the Dr’s comment about if it is not disrupted it is fine. As a pet owner sometimes un disrupted pet hair will sit in the corner of a room or under a counter un disrupted but I still clean it when I notice it. Just because you cant see it doesn’t mean you should leave it there to collect more and more. The people that don’t want there air ducts clean either simply cant afford it but would like it done. OR! the crowd that are to cheap.. You should Clean all portions of your house.
Good article, but it fails to point out that leaky return-side ducts could be drawing dust and allergens into the duct system from the enclosed spaces in which they run, e.g. between walls, below floors, attic. So duct cleaning may only be a temporary solution. The homeowner can get a home energy audit -- free in many states -- to determine if they have significant duct leakage. An Aeroseal dealer may be able to effectively seal up the duct system without needing to tear into walls etc to get to the ducts.
Once on the scene, trained Sears professionals utilize powerful, truck-mounted equipment to clear your air ducts of dust, debris, pet dander, allergens, and grime. Our powerful air duct cleaning suction equipment vacuums out years of accumulated dust from your air ducts, leaving them clean and clear. Once finished, our technicians remove all equipment and make sure that your ducts and HVAC unit are restored to their best condition. For continued protection against dirty air ducts, your service technician may suggest a variety of air purification products.
Metal is way better than flex duct or ductboard. It gets better airflow, holds up to critters and duct cleaners. I know of no hvac company here that cleans ductwork. (there probably is one somewhere) The mfg's of duct cleaning equipment keep trying to sell us hvac people on their benefits and profit potential but most all hvac people know that unless you have metal ductwork you are NOT doing the customer any favors.
Well, I had the cleaning done. The handler is definitely much quieter. It was explained to me that with the coils clean, the condensation will be able to sweat off instead of sticking to the dust and dirt, therefore the humidity (lots of humidity in florida) will be removed better. I feel as if it was worth it, but, I will definitely change that filter every 3 weeks or so from now on. I don’t want to pay that cost again.
Preventing against air leakage is great, but the only way to keep dust and debris out of a duct system would be to completely seal off the return-air side of the system, which would render the system useless. Cold-air returns will always pull dust and other particles into the system. A high-MERV rated filter is definitely a good idea, but it does nothing to keep the return side of the system clean. Definitely agree though to use foil tape to seal seams, etc. Duct tape dries out over time and as it does can actually add more particles to the air.
You may be familiar with air ducts that are constructed of sheet metal. However, many modern residential air duct systems are constructed of fiber glass duct board or sheet metal ducts that are lined on the inside with fiber glass duct liner. Since the early 1970's, a significant increase in the use of flexible duct, which generally is internally lined with plastic or some other type of material, has occurred.

A year and a half ago (fall of 2015) we replaced the furnace and air conditioner. From what we could determine this was the third forced air furnace and second air conditioner unit for the house. As part of the installation, we changed out the two 6″ ducts feeding the second floor with 8″ ducts. The idea was to get more cold air to the second floor in the summer. It worked and for the first time the second floor and first floor temperatures were the same when the air conditioner was running. Of course, to make the system work I close down upstairs duct damper doors in the winter and open them up in the summer.

Most people are now aware that indoor air pollution is an issue of growing concern and increased visibility. Many companies are marketing products and services intended to improve the quality of your indoor air. You have probably seen an advertisement, received a coupon in the mail, or been approached directly by a company offering to clean your air ducts as a means of improving your home's indoor air quality. These services typically — but not always — range in cost from $450 to $1,000 per heating and cooling system, depending on:
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