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.
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 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 $100 to him for my lesson to learn and search online to find this site is very helpfully and I should do it before to call anyone for air duck cleaning.
Furnace cleaners are mostly young men, I know this, I have been one for 15 years or so……so heres the truth, if there are any allergies, children, older people with health issues, we are GOING to make money. do not tell the company you have hired about any health complication. they are salesmen. and they don’t care about you. or your money. make sure they do a good job, then kick them out. you don’t need all the bells and whistles they wanna sell you. any idiot can clean duct work, like I said, I am one of them. I am very good at it, but I don’t have the back bone to sell a widowed old lady a humidifier that she doesn’t need for 500 bucks, overall, if you think you need this service done, which you probably don’t, get it done, do not spend anything over 300$ and do not do it again for at least ten years.
if you do not want to put that dryer cleaner down your ducts (I don’t because if it gets stuck somewhere you will be stuck calling a pro to get it out! anyway what I did was take the furnace filter out for max air flow, and then close off all your vents leaving only one open at a time to clean. This directs all the air from your system only to the vent going to the opening you are cleaning. Then stick the flexible tubing of your vacuum cleaner down a bit into the vent and turn on the vacuum. Then go to the thermostat and turn on the fan only and let the vacuum run for a few minutes. That does a great job and you can do it with or without the brush. When done put a fresh filter in. I only do this for the vents where the air blows out. I would not recommend cleaning the cold air returns this was as you would likely be forcing dirt and dust into your furnace. If you want to vacuum the cold air returns, turn the system off
I had them out to clean the ducts, exhaust fans, and dryer vent in my 54 year-old home yesterday. They showed up a bit early and took their time to ensure that all the grunge was gone. I must say...they really earned their paycheck with this place! The father and son duo worked together to remove and clean the register covers, ream out the ducts and vents with a big furry brush/vacuum unit, and vacuum up the mess. They stated that I had the dirtiest ducts they had encountered in 15 years, and took over two hours to tidy them up, finding nails, copper pipe and assorted detritus and emptying the vacuum bag three times in the process. They were here over 2 1/2 hours, yet charged the fee they had quoted me on the phone, as promised. It was not the cheapest price I have seen, but it seemed fair to me. Interestingly, I had this service performed several years ago, by a cheaper company. Based on the amount of dirt and junk that was removed yesterday, I now have my doubts that the previous company really performed the work. Yes, I checked this time! The owner, John, told me that there is another company working under the same name, so make sure that you are getting the Arizona Air Duct Cleaning Company, father and son team, that is being reviewed here. Not all these companies are honest and do what they claim to!
Read before purchasing Groupon! The Groupon offer seems like a great deal but it only includes a maintenance cleaning and not a full cleaning. They basically vacuum the vent with a shop vac. I had to argue with the techs just to get the dryer vent cleaning that is supposed to be included. When I called the office about it they said it was up to the technician to include the dryer vent cleaning but it wasn't automatically included. When I read the fine print on Groupon to her she said Groupon has worded it wrong and won't change it. Very deceiving "deal".
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.

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:

Demonstrate visible evidence of microbial growth in your duct work. Some service providers may attempt to convince you that your air ducts are contaminated by demonstrating that the microorganisms found in your home grow on a settling plate (i.e., petri dish). This is inappropriate. Some microorganisms are always present in the air, and some growth on a settling plate is normal. As noted earlier, only an expert can positively identify a substance as biological growth and lab analysis may be required for final confirmation. Other testing methods are not reliable.
Some research suggests that cleaning heating and cooling system components (e.g., cooling coils, fans and heat exchangers) may improve the efficiency of your system, resulting in a longer operating life, as well as some energy and maintenance cost savings. However, little evidence exists that cleaning only the ducts will improve the efficiency of the system.