Internal insulation provides better acoustical (noise) control. Flexible duct is very low cost. These products are engineered specifically for use in ducts or as ducts themselves, and are tested in accordance with standards established by Underwriters Laboratories (UL), the American Society for Testing and Materials (ASTM), and the National Fire Protection Association (NFPA). Many insulated duct systems have operated for years without supporting significant mold growth. Keeping them reasonably clean and dry is generally adequate. However, there is substantial debate about whether porous insulation materials (e.g., fiber glass) are more prone to microbial contamination than bare sheet metal ducts. If enough dirt and moisture are permitted to enter the duct system, there may be no significant difference in the rate or extent of microbial growth in internally lined or bare sheet metal ducts. However, treatment of mold contamination on bare sheet metal is much easier. Cleaning and treatment with an EPA-registered biocide are possible. Once fiberglass duct liner is contaminated with mold, cleaning is not sufficient to prevent re-growth and there are no EPA-registered biocides for the treatment of porous duct materials. EPA, NADCA and NAIMA all recommend the replacement of wet or moldy fiber glass duct material.
Air duct cleaning service providers may tell you that they need to apply a chemical biocide to the inside of your ducts to kill bacteria (germs) and fungi (mold), and prevent future biological growth. Some duct cleaning service providers may propose to introduce ozone to kill biological contaminants. Ozone is a highly reactive gas that is regulated in the outside air as a lung irritant. However, there remains considerable controversy over the necessity and wisdom of introducing chemical biocides or ozone into the duct work.

I've been in business in Florida for 25 years and purchased a $12,000 duct cleaning system 4 years ago. In the last four years I've cleaned 5 duct systems charging around $400 each. Not a very good return on investment. What I have been doing most the time is I get a call by someone panicked because they called some low priced company to inspect their system and were told they have dangerous black mold. Then they call me to have a look. Most the time they don't have mold, ducts look very clean. However the coils are dirty and the inside of the air handler cabinet needs cleaning. Keep in mind not every system can handle supper high efficiency filters! These filters can block air flow quite a bit right out of the package. Many older systems can't handle pleated filters due to increased static pressure. "Back rooms with low air flow". I have taken many hours of classroom study on indoor air quality. Never got any certification because I don't want to pay another organization dues yearly. I think the problem with duct / system cleaning is most people are suckers for low priced scams that are rip- offs . People call me all the time and ask how much? When I tell them average $400 they hang up. I know I do the job correctly and honestly, and they are going to get racked over the coals by the scam artists by calling $79 whole house duct cleaning guys. People need to check internet, angies list and BBB reviews. But keep in mind even reviews need to be sifted through your rational person filter.

If your non metal ductwork is that dirty you should just have it replaced AND sealed. Also most duct systems are not very well designed. Look for proper sizing and do not go cheap with one or two intakes (return grills) You need them through-out the house. Here in Austin the duct cleaners are carpet cleaners and chimney swifts. (this is who the duct cleaning equipment mfgs call on when the hvac people do not get on board. They DO clean other types of ductwork and we (the hvac guys) have to fix them. I am not aware of any of these non hvac guys cleaning and servicing the actual equipment. Here in Texas it is against the law for them to do so. Treat the entire house as a system, not just the ductwork and /or hvac equipment. Home performance really does work to increase comfort and air quality while reducing operating costs.

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:
Just had my air ducts cleaned. They used a high pressure air hose in all the heat ducts and cold air returns. He showed me the stuff that came out, the reason for the duct cleaning was the fact that I had a problem. With rodents. There was quite a few mummified rats and mice, and he said I wouldn’t have to have them done again unless I incur another problem or have renovations done. Cost me 345.00 for a 2 storey large old home. Not a bad price as I had them done when I moved in 28 years ago and it cost me 500.00. Lots of dog hair, toys, balls and assorted goodies came out as well. Took them 2 hours. I did have sanitizer put in the ducts because of the dead rodents.
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.
To find companies that provide duct cleaning services, check your Yellow Pages under "duct cleaning" or contact the National Air Duct Cleaners Association (NADCA) at the address and phone number in the information section located at the end of this guidance. Do not assume that all duct cleaning service providers are equally knowledgeable and responsible. Talk to at least three different service providers and get written estimates before deciding whether to have your ducts cleaned. When the service providers come to your home, ask them to show you the contamination that would justify having your ducts cleaned.
I guess, I will start with saying that air duct cleaning is almost never needed. It is not a scam, but it is certainly something that uneducated homeowners get suckered into. In regards to air flow, a well balanced HVAC system should be able to deliver more than enough air flow. If you are not getting good air flow, it's because your system may be out of balance. Additionally, regular cleaning/changing of the air filters will solve about 95% of your problem. Though you would be surprised how many people either a. don't have a filter or b. don't know about it and leave it there for 10+years. a washable one should be cleaned every 6 months(spring and fall) and a disposable one should be replaced every 3-4 months.

We moved to a house built in 1965 from a 1915 house with a dirt basement. Against what I anticipated, the 1965 house was much dustier. It was like felt on top of everything. I cleaned and cleaned and it did become less dusty over time. We then found out a cat lady with over 2 dozen cats lived in the house in the past. We then had to get our furnace replaced and I was able to look down some of the duct work, the dirt and debris was 3-5 inches deep. Additionally, the basement ducts were entirely plugged with debris including dirt, seeds, ants, toys, etc. I had already removed what I could from those. We had our ducts cleaned last year, and the dust in the house is greatly reduced. Also have lost the runny nose I got after moving here. There are duct cleaning con artists out there, but ours did a good job.
A thorough visual inspection is the best way to verify the cleanliness of your heating and cooling system. Some service providers use remote photography to document conditions inside ducts. All portions of the system should be visibly clean; you should not be able to detect any debris with the naked eye. Show the Post-Cleaning Consumer Checklist to the service provider before the work begins. After completing the job, ask the service provider to show you each component of your system to verify that the job was performed satisfactorily.
I called a company name “GREEN RHVAC” with their $29.00 one system air duck cleaning. When the guy came with a truck I asked him to tell me how much he will charge and he said that if he gave me price and I didn’t want the service then he would charge me $89 or he would tell me how much he charge me after he finished the work. I immoderately sense that I made mistake to call him to my house. To cut my lost I asked him to give me the price and it was $1600 for two systems house. I paid $100 to him for my lesson to learn and search online to find this site is very helpfully and I should do it before to call anyone for air duck cleaning.
Although i love to burn candles, depending on the type your asking for problems big ones! At work one day i had been talking with co workers about these black shadows that were appearing on my ceilings and higher wall areas. They seemed to in the corners and along the stud supports , i could even see what i thought to be where all had been nailed. There would be dark shadows perfectly straight across my ceiling and then real dark circels every few inches within the lines. I thought it was the propane heat but learned quickly that oil heat will do that but not normally propane. A co worker brought me a magazine with a huge article about candles and what actually burns off them when lit, an ashy soot that is attracted to the areas on walls and ceilings that omit the most heat or warmth, of course where the drywall and studs meet and corners of the room. Its been about 8 years since i painted the entire house. I started bending to my love for candles again in the last 3 years, surprise i will be spending part of my summer re painting again!! No more candles ,well maybe at the holidays LOL
In addition, the black dust was found in most of the heat registers. He could rub it off on his fingers but did nothing but spray compressed air on it which didn’t make it disappear since it wasn’t loose. Also, in the register in the basement he described the black dust as being oily. The reality of that situation is that I had the AC on until the morning of the service and minutes after he snaked the hoses in my back door it started raining. The basement register had condensation from the humidity all over it. It was not oily but wet. He asked for an old towel and wiped it out. Never saw anything so black – because I never had to clean soot. That is what I have in my ducts. Soot from years of the old coal furnace.
Very interesting article. I searched articles about services for cleaning ventilation systems. But I have some questions. For cleaning ventilation system used special products for cleaning. Can I know in company manager about, which type of cleaning products they use? Your family members may be allergic in some components. It’s very big problem. And one more problem it’s how to choose the right company in Internet. Sometimes I don’t have much time to find a company in my town and I use the Internet. But I find a lot of company. It is very popular services, for example, Stanley Steemer – https://www.stanleysteemer.com/ or my local not very popular service, for example, AllstatesAirDuctPro – http://allstatesairductpro.us/. Can I understand the company is professional or not, only looking through the website? What must I check on the website? Who has helpful information? I will very grateful for your help. Links I add for understanding my problem. They are random and not for advertising.
The key to the continued and efficient operation of your heating and cooling system is periodic maintenance. Cleaning the air duct vent system, and servicing you heating and cooling equipment will keep the system operating at its peak performance. Air ducts are cleaned for two reasons. One: to prevent debris from entering furnace and air conditioning components. Two: to prevent debris from cycling through the home. The air duct cleaning contractor needs to employ cleaning methods which successfully removes debris, and ensures that debris does not enter the occupied space. Most contractors can verify the results of the cleaning through video or pictures.

I purchased one of those Amazon air duct cleaning coupons for 49.99. When the company showed up, they removed the vent closest to the air intake and immediately told me I needed $1800.00 for all new duct work. They said they could not clean the system until new duct work was installed. I thanked them and said I would give them a call. The only call I made was to Amazon to get a refund. I know I didn’t need new duct work. Be careful to not fall for unscrupulous salesmen and their pitches and scare tactics.


I just had my blower module replaced because my AC coil was frozen over. The underside of my coils had a thick mat of dust because I had never had it cleaned. I cleaned it myself by using a soft brush attachement on a shop vac. The inside of the blower appears to have a white/green growth, and I am sure the ductwork of my 30 year old house can’t be in good condition.
2. If air quality is so important and duct cleaniliness is so uncertain, why not adopt doubling filtering; that is, in addition to the existing main furnace filter, add a filter at each air outlet. I understand replacing so many filters would be a burden, but air outlets can be designed for easy filter replacement. The builders and home design engineers should bear responsibility to provide good and low maintenance homes, rather than prioritizing on fancy or costly featuers for homes.
The short answer is yes, duct cleaning, done right by a reputable company will help with the smell. It is likely though the smell is coming from another source, ie the crawl space. It could also be that another rodent is dead in the duct work. A visual inspection would be in order to check for any breach in the duct system. A duct pressure test would be able to tell you how much air is leaking from the system over all. A hole large enough for an animal to enter would loses a great deal of air, over 300 CFM. It would be worth looking into having this test done and it should cost around $200. Cleaning the air handler and evaporator coil will greatly improve the performance of the air conditioner. Dirt and dust on the evaporator acts as insulation and reduces the amount of cooling done be the coil. Any quality duct cleaning should include cleaning the air handler and coil, and the tech should allow you to watch him perform the work as it is done.
fact is most homes have bad filter racks. when you insert the filter it doesn’t seal well to the sides so some of the air and dust bypass it and end up in the supply ductwork and into the house. Most of the dust in the supply ductwork settles down and doesn’t get blown in the house but some of it does when the blower starts up or when you put a new filter. If you have allergies or other health problems put in an electronic air cleaner, get your ducts cleaned and run the fan as much as you can afford. you can also get an ECM motor installed which is going to be worth it if you want to run the fan 24/7. If you have uninsulated metal ducts take down the ones you can and wash them. Then put them back and seal the joints. Cleaning the ductwork also improves airflow which is important to AC and Heat pump systems for efficiency. An electronic air cleaner will also improve airflow and static pressure because they usually have a much larger filter surface area. An electronic air cleaner also keeps the ac coil clean like new which means better efficiency and no cleaning needed. AC furnaces sometimes grow mold around the coil because of the condensation. Electronic air cleaners should be able to filter mold spores but the best remedy is installing a UV light next to the coil which will kill the mold.
A do-it-yourself approach will only scratch the surface because it is hard to reach some of the ventilation running underneath the floor or into the wall. Although it may help in clearing some of the dust and debris, you really need a professional to guarantee your system is truly spotless. The proper procedure involves the use of a powerful vacuum system with multi-brush attachments designed to loosen debris and feed into the suction. Particles are then blown outside of the house or passed through a HEPA filter inside.
I hired duct cleaning company out of "Service Magic" website. I did not realize the name of his company was Duck cleaning of Central Florida...that should have given me a hint.. The guy did a very poor, incomplete job, and ruined a closet full of clothes when he sprayed up to clean a vent instead of taking it down and cleaning it outside. He left me with more than 1/2 dirty vents and ducts, did not do the air handler in the garage and failed to fog the system. He spent 6 useless hours at my residence and now his insurance is denying coverage..very disappointed in Service Magic....

All of you have dentists, you have doctors, you have preachers, you have mechanics. You don’t have to know everything about everything but you have to have people in your life that you can trust. Don’t just open up the phone book and pick a mechanical (HVAC) contractor. Call your friends and family and ask for referrals. There are no black and white (scam or not a scam) answers here.

On average, we (Indians in Ontario) receive 3-5 calls per day for duct cleaning services from India. I did get ducts cleaned twice in 25 years. For a newly built house, it should be done as material goes into the ducts. Every year, before turning the heat on, I clean the ducts, using the vacuum pipe or with wet towel. Most of the dust, pet hair, small items get to the ducts from the top floors, not where system is installed. Even in winter months, I open 2-3 windows for air circulation for 15 minutes, specially right after cooking, almost daily. We breath in the same stale air, develop health issues. Also, I have an added air cleaning and fileration system installed. At a low rate, this system constantly cleans the inside air and also that it pulls from the outside. Duct cleaning is a scam, there are other efficient and cost effective methods we can use to purify the inside air.


On the other hand, if a service provider fails to follow proper duct cleaning procedures, duct cleaning can cause indoor air problems. For example, an inadequate vacuum collection system can release more dust, dirt and other contaminants than if you had left the ducts alone. A careless or inadequately trained service provider can damage your ducts or heating and cooling system, possibly increasing your heating and air conditioning costs or forcing you to undertake difficult and costly repairs or replacements.
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