Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in the cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season.
Here in Frisco, TX…just had a tech come out to clean vents. I used a 30 bucks groupon for “complete vent cleaning”. He told me I have 3 AC units and groupon covers only 1. I told him to do the unit upstairs where the kids sleep. He decided on his own to do the downstairs unit. I yelled at him why he is not doing the unit I told him to do! He said they are all connected. I will clean two for you for the price of one… Oh really?
I to had an odd layer of white'ish dust building up especially during seasonal periods when the HVAC ran a a lot. I carefully swept up the fine dust into a small pile and had it analyzed. Turns out it was very fine fiberglass powder dust. It turns out it is the insulation form the attic! (My attic has blown in insulation). Turns out if you (I) had small gaps around my HVAC registers in the ceiling whee the airs blows into the room. What occurred in my case was that the exiting air at that seam creates a vacuum effect at the grate vent cover and draws and then blows fine insulation dust from the attic into the house. Removing each register grate and sealing each tin outlet gap with calking between the dry wall ceiling and tin fixed the issue. A couple were so bad with bowed gaps I had to screw down the bowed tin to the attaching stud better. Checking the very same glass top desk that catches and shows any dust accumulation now shows only very small amounts of normal house dust build up over several weeks. A big, big improvement. You might have a look by simply removing a couple vent covers yourself.
I am very interested by your post. We recently had a lead inspection on our property and one thing the lead inspector suggested was to get the air ducts cleaned out. We had our ducts cleaned last year after we under went a large renovation project (since we have a toddler in the house). This year we decided to go for lead compliance and had all our lead removed (we moved out for the work). Recently, my son had a false positive lead test, which prompted us to get a lead dust inspection around the house (including having the vents dust-wiped on the inside). The levels inside the ducts weren't crazy high (but more than would be acceptable for a floor). As it turned out my son's lead levels are very low (but not zero). Is it possible however that lead dust from the inside of a vent can come out? Would this be a scenario where you think air duct cleaning would be beneficial?
All modern air conditioning systems, even small window package units, are equipped with internal air filters. These are generally of a lightweight gauze-like material, and must be replaced or washed as conditions warrant. For example, a building in a high dust environment, or a home with furry pets, will need to have the filters changed more often than buildings without these dirt loads. Failure to replace these filters as needed will contribute to a lower heat exchange rate, resulting in wasted energy, shortened equipment life, and higher energy bills; low air flow can result in iced-over evaporator coils, which can completely stop air flow. Additionally, very dirty or plugged filters can cause overheating during a heating cycle, and can result in damage to the system or even fire.

For more than 60 years Stanley Steemer has been perfecting our hot water extraction method to clean carpet with unparalleled results. Take control of the environment in your home and enjoy a cleaner, healthier living space for your family. Every carpet cleaning is Certified to remove an average of 94% of common household allergens. We remove the dirt you can see and the allergens you can't. 
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.
The jury is out on whether or not cleaning your air ducts and vents has a significant enough impact to be necessary. A proven connection between immaculate duct systems and air quality in the home has not been made. However, if your vents display any of the signs listed above, cleaning would certainly be in your best interest. Allowing mold, debris and bacteria to fester could create bigger problems down the line. If having your system disinfected is within your budget, you may prefer to take care of these issues rather than ignore them.
Quality and price should come hand in hand, a too-good-to-be-true price for an efficient air duct cleaning will not give you the quality that you wanted. To make sure you are getting your money’s worth, check reviews of air duct cleaning companies, certifications from industry since this work requires continuous learning due to new techniques and research breakthrough from time to time. Make sure to shop around and get written estimates first.
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.
Two weeks go by and no phone call from HVAC Service regarding install date, or any update at all.  I call them to check in to see if they have put me on the schedule and when I can expect to have the AC installed.    You can tell by the discussion I had with the lady on the phone that they completely forgot about me and have not scheduled anything.  She says she needs to get in contact with the owner because she has no idea on the availability of the crane.  I was told that she would call me back by the end of the day with an update.  Surprise, surprise, no phone call.  
While your HVAC filter is designed to trap particulate matter and prevent it from entering your air ducts, particles often still get through. The number of particles your HVAC filter traps is directly connected to the quality of air in your home: the lower the quality of air, the more particles will be present, and the more particles are likely to get through the filter. If these particles are allowed to build up, your HVAC system can become less efficient, operating longer to heat or cool your home. An inefficient HVAC system can result in inconsistent heating or cooling, higher utility costs, and expensive HVAC unit repairs, such as an A-coil or blower motor replacement if the problem is left unchecked. Air duct cleaning from Sears, which focuses on the dirt in your air ducts, can boost the efficiency of a dirty HVAC system, cleaning out the particulate matter that can hinder HVAC effectiveness and affect your health.
CIBSE publishes several guides to HVAC design relevant to the UK market, and also the Republic of Ireland, Australia, New Zealand and Hong Kong. These guides include various recommended design criteria and standards, some of which are cited within the UK building regulations, and therefore form a legislative requirement for major building services works. The main guides are:

I was with you until you said avoid steaming cleaning or moisture, there is no way you can remove mold or any other type of biological without moisture. The best way to do this is in fact with a steamer using a commercial disinfectant and a non reactive odor remover so your home smells refreshed and not like a hospital . This is directly contradictory to your article.
Quality and price should come hand in hand, a too-good-to-be-true price for an efficient air duct cleaning will not give you the quality that you wanted. To make sure you are getting your money’s worth, check reviews of air duct cleaning companies, certifications from industry since this work requires continuous learning due to new techniques and research breakthrough from time to time. Make sure to shop around and get written estimates first.
I just had my Air ducts “cleaned”. The person who came to my house works for an air duct cleaning company who uses a professional vacuum. He said the company would charge me about $900 but he can do it aside on his own and charge me half of that. However, when he came over the house, he brought the rotary brush along with his domestic vacuum cleaner that it’s hose was about 5 feet long, I ask him that the wasnt strong enough to pull dust out, and he said, it’s similar to what companies use. I was in doubt and he didnt cover the vents so im thinking all dust must have come out from every air vents. Could this vacuum have taking the debris out of the air ducts? Or how can I myself find out if the inside of the air ducts have been cleaned and no debris is sitting there? I have dust all over my house.
I think that the coding and permit industry is a joke!! They will not allow the homeowner to apply for the permit it has to be the licenced contractor. It would make since to allow the homeowner to apply for this. But it is all about money!! They really don't care if its up to code because if they did then they wouldnt care who applied and payeed for it, but they want the contractor to do it so if they do something wrong they can fine them instead of just pointing it out and allowing them to do it right.
Had our ducts cleaned late April, 2016. Sodium Chlorite was sprayed into ducts after cleaning. Ever since, we have been bothered with eye and nasal passage irritation because of a “chemical” and “musty” odor. This odor is present whether or not a/c is on.) We are told the sodium chlorite (“EnviroCon, manufactured by Bio-Cide International) is used in hospital and nursing home settings and is not hazardous to health. The air duct company’s suggestion is that they come out and spray even more sodium chlorite…we absolutely don’t want this done! Have had various other recommendations about what we need to have done to remedy our problem. We will be unable to stay in our home if a resolution cannot be found. We’d be willing to replace the ductwork if necessary. (One professional suggested that the cleaning may have “knocked something loose” inside the ductwork and that is the source of the irritant.) This home was built in 1920…no idea when the present ductwork was installed. Any suggestions would be appreciated.
As a homeowner and an owner of rental property I can tell you that the air ducts sometimes need to be cleaned. If you have had pets or anyone smoking in your home (even a visitor) for any length of time, having the ducts cleaned is really good idea. I had a tenant who did not smoke, but got married to a smoker more than year after moving in. When I realized someone was smoking I had them move out, but the smell was awful. I had the ducts cleaned and sanitized (it was a bit extra). The ducts were shiny like new afterwards. I left the windows open for a few days and we cleaned the place super clean and then replaced the carpets. The duct cleaning was worth every penny because the house looked, smelled, and felt new afterward. I plan to have my own house ducts cleaned again this year as we have two cats. We had them cleaned about 12 years ago and they found building materials in the ducts! If you move into a house that has never had them cleaned, it is good to do it. If you have allergies, clean the ducts to see if it helps. You never know what is in your ducts if you have never had them cleaned.

Greetings from Mama Duck from Ductz of Greater Atlanta. These are some awesome comments and a few are from high quality duct cleaners that I personally know. After 19 years in this industry I agree that a government agency is not always up to date with their knowledge but won't admit it. If they were out in the field with our technicians every day they would upgrade their info. I get calls all the time where customers have been taken advantage of by "go and blow" companies. The customers don't know what they don't know but many are too lazy to do the research and are just looking for cheap. The industry has gotten a bad rap due to these con artists but the customer has to take some responsibility. I ask them why they would want to do business with a company who lies to them in print? Are they stupid or just cheap? Thankfully there are those of us in the industry who are working diligently to raise the bar on quality, protect the consumer and perform high quality work. At Ductz all our technicians are NADCA certified, trained by the best in the industry and know how to clean the entire system.


No matter what time it is, our experts will have you lounging in the cool air of your home quickly. We stand by our workmanship so much so that we guarantee it in writing for one full year. Our 100% Satisfaction Guarantee* firmly backs our dedication to providing the highest level of air conditioning service in the industry. In fact, Service Experts repairs, sells and installs more air conditioners than any other HVAC company through North America. More people count on us for their home comfort, so you can be certain your home will be back to being cool and comfortable in no time.
I'm very glad that I found another guy to come replace the circuit board and put it away from the water, fix the water leak, and also find and fix another impending failure.  All of that was for much less than HVAC Service wanted to charge for repair or replacement. The other guy did a great repair, so I'm confident it will not break down again, but if it does, I will not call HVAC Service. Don't get suckered by their Yelp Deal.
I originally took off one star because of the SNAFU with getting the part ordered.  When Alberto called me on the phone he admitted the person had "gotten busy with other things" and apologized.  THAT was taking the high road and I was impressed by that.  Sadly, for reasons I won't guess at, Alberto has decided to take the low road in his comments and imply that they got the part as quickly as possible.  Well, we called at 2:30 so did someone spend six and a half hours finding the part??  That seems very doubtful.
The original furnace was a coal fired “octopus” design which had no blower to circulate the air but relied upon warm air rising to distribute the heat. That also means that the system breathed air in from the basement and most of this type did not have a cold air return system. At some point (probably in the 1940’s) the system was upgraded to a forced air gas furnace. The upgrade included replacing the 12″ diameter air ducts exposed in the basement with 6″ ducts and a cold air return system of ducts from the two (only two) air returns on the first floor.
I am 79 years old, bought a condo & spent a lot of money on it. this winter my first bill was 450.00. had my furnace checked out, which is on the roof. it was old rusted out & leeking oil. i talked to owner & had new unit installed. they came out to clean ducks & they were split & worn out. there is no crawl space because theres a unit above me. my real estate lady or this company will not help me fix this problem.
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.
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