You've probably seen the ads in the newspaper or in your mailbox: a huge, frightening-looking dust mite accompanied by warnings that your health could suffer from dirty, moldy air ducts. But have no fear: for a low price, like $49.95, you can have them cleaned — you might even get a 10 percent discount if you're a senior citizen.According to the Better Business Bureau, it's a scam called a "bait and switch," and the BBB says it's happening all across the country. In fact, the BBB claims that dozens of connected companies are involved in the airduct cleaning scam, systematically ripping off homeowners for more than a decade to the tune of millions of dollars.Over the years, hundreds of homeowners have logged complaints with the BBB, all sounding similar: Once inside a customer's home, technicians routinely mislead them into paying hundreds or thousands of dollars for additional work. Many were told they had dangerous mold. Others had their homes unnecessarily flooded with noxious chemicals.

Some said they were afraid of the workmen. All said they were duped into paying hundreds more than the promised $49.99 advertised price.It sounded like a story for the Hansen Files, a new franchise from NBC's Dateline, so we began our own investigation.We found senior citizen volunteers who allowed us to wire their homes with hidden cameras to see what would happen when we responded to one of the ads. Even we were stunned by what we saw. Not only did our cameras catch the technicians scamming nearly $500 from our volunteer, they actually left the house in worse condition than before they arrived.A few weeks later, we asked our volunteer to make another appointment, this time to have her furnace cleaned. And this time, Chris Hansen was there to let the technicians know our cameras had recorded their scam, and to see what they had to say.Early on, we learned reporting this story wouldn't be easy. We began by digging into one company, and then another, and then the histories of some of the people behind them.

We found many of the businesses opened up shop only to disappear within a matter of months, but would then appear again under a different name. Sometimes, it was even hard to determine exactly who owned many of them. The paper trail left behind was limited and sometimes inaccurate. One business was registered using the name of the real owner's dead stepbrother. Another was registered in the name of an owner's bodyguard. Several to convicted felons, one a killer.But our reporting led us to one revealing fact: dozens of the rogue businesses all across the country were run by a rotating list of the same individuals who kept popping up over and over again.As we began to connect the dots, we saw that some attorneys general and judges have ordered these companies to be shut down, forbidden their owners from doing business in their states, and ordered them to pay hundreds of thousands of dollars in damages. But most of the time, the scammers simply took off to set up shop in another state.Bottom line: If you think you need your air ducts cleaned, check with both the Better Business Bureau and the National Air Duct Cleaners Association before answering the cheap ad in the newspaper.

Watch this Web-exclusive video of Chris Hansen confronting air duct cleaners: And here's a closer look at the dirty business of air duct cleaning scams, and how you can avoid them, with Michele Mason of the Better Business Bureau:To watch the full story on air ducts, follow this link. best way to clean stains off couchAnd here's the full episode of Hansen Files, with additional looks at psychics and the questionable backgrounds of professionals.best vacuum cleaner brand nzYou can see more on the Dateline home page.best rated upright vacuum cleaner by consumer reportsDo you have ideas for an investigation? laptop fan not spinning after cleaning

Share your story ideas with Open Channel Send us a document Follow Open Channel on Facebook Keep up with Open Channel on Twitter Sign up for e-mail alertsgood vacuum cleaner brands in malaysiaDuct cleaning is a methodical, straightforward process that delivers clear results. best steam vacuum cleaner for hardwood floorsHowever, you might not know it from watching cheap, fly-by-night duct cleaning contractors work. Their spurious methods often take a fraction of the time as an accredited professional’s, and disappointing results can leave a homeowner wondering exactly what, if anything, was done. Unlike their industry’s outliers, legitimate duct cleaning contractors are eager to educate homeowners about the National Air Duct Cleaning Association’s (NADCA) standardized methods.

These procedures establish how to properly clean ducts as well as registers, filters, plenums, evaporator coils, and air handlers—almost every component of a forced-air HVAC system—and the results will be obvious. The methods used by accredited contractors are called source-removal techniques by NADCA, and they involve cleaning the ducts by hand and with compressed air tools while a vacuum collection device extracts dislodged dust and debris. Read on to understand more about the duct cleaning industry’s best practices. A simple visual inspection of the ducts leading to the return and supply registers is important for two reasons. First, it’s a step homeowners can take themselves to assess the level of buildup in the ducts beforehand and confirm the difference after they’ve been cleaned. (A duct cleaning contractor will likely have cameras that can probe even farther into the ducts and show the full extent of the buildup prior to cleaning.) Second, when a professional performs the inspection, it affords an opportunity for the technician to check the ductwork for leaks or, in the case of flexible ducts, kinks;

many duct cleaning contractors are also capable of making repairs and replacing ducts. Basically, duct cleaning contractors use large, portable or truck-mounted vacuum collection devices to suck dust and debris out of your ductwork. However, before turning on the suction and scrubbing the ducts, the technicians must perform a few preliminary steps. First, they must hook the vacuum collection device’s large hose to a duct close to the air handler—the heart of your HVAC system. The technician will simply cut an access hole in the duct, insert the vacuum hose, and seal where they join as tightly as possible. (Note that your HVAC system includes a supply side and a return side—ducts that send treated air into the rooms of the house, and ducts that return air to the air handler. The supply side and return side are separate, and the duct cleaning process must be performed on each.) Even an extremely powerful vacuum collection device will be ineffective if the registers in each room of the house are uncovered, so the technician should seal those with adhesive covers.

Turning on the vacuum will now create negative pressure, and particles inside the ductwork will be sucked into the collection device as they’re brushed or blown loose. Once the system is under negative pressure, the technician will uncover each register and clean the ducts one by one. One thing that distinguishes a NADCA-certified duct cleaning contractor from a fly-by-night is the amount of time each spends per register. Improperly trained technicians have been known to move on after a quick burst from an air compressor and a spritz of disinfectant; this technique is largely ineffective and usually results in dust being blown back into the room. Legitimate technicians will use rotating brushes, compressed air tools, and simple vacuum cleaners to ensure dust is dislodged and sucked into the vacuum collection device. NADCA recommends cleaning the other components of the HVAC system as well, including the air handler’s blower motor, evaporator coil, and drain pan.