Dude, there are like twelve links to studies in that one link proving this. Plus, the EPA found the exact same thing! What more do you want? Seriously, it is what it is. Here is what the EPA (the EP fricking A) said:
“Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts.”
Yes, I am certified Ductologist. </sarcasm> No, of course I don’t have a background in it, because it is a scam.
No, they were being scammed. It is simple logic, if the dust is stuck in the ducts, then it isn’t in the air. If it is in the air, then it isn’t in the duct.
I'm interested in the straight dope here, but have no vested interest other than that in this thread. (Not a contractor nor vendor)
The typical ducted system is comprised of supply and return ducts. The returns are where dirt, dust, cats and the like enter, and get carried to the extent velocity, mass and "stickiness" permit. A well designed system will not allow most of this matter to pass into the supply side . The division takes place at the filter, often before the blower/fan. Even coarse filters would prevent visible matter being blown OUT of the duct.
P.S. You should try to keep the cats out. We’re talkin’ experience here.
Don’t I know it. Our old house has a chute from the floor in the living room to the furnace in the basement. Back in the day, it was the only source of heat in the house. Anyhoo, when cleaning it, the cats have to be locked up so they don’t hop into the furnace!
Dude, I am a contractor and have experience with this for 20 years or so. (an HVAC contractor actually, and have seen many, many cases in real life.)
That said, I agree with you mostly, actually. I think that duct cleaning is mostly unneeded and almost always oversold. I’ve seen first hand that the duct cleaning machines get much, but rarely all, of the dirt/duct found in ducts. And I don’t think that they do a whole lot to improve IAQ.
But I think you’ve overstated your case. I have seen older furnaces removed (that had low flow, low velocity belt driven blowers) replaced with new furnaces (direct drive with high CFM and velocity) that picked up dust from the duct and deposited it pn the coffee table for weeks.
I’ve also seen many homes that went through major remodeling and the ducts had pounds of drywall dust that was distributed into the home for weeks.
The overwhelming amount of the filter arrangements I’ve ever seen allow air to bypass the filter. In my view and experience, Carson O’Genic made the best suggestion: get a good filter, in a well sealed enclosure and that filter will capture the dust. It’s a much better investment and over the long term will do a better job.
So I agree with you in general, but the blanket statement that all duct cleaning is unnecessary and a scam is overstated and untrue.
raindog
A non-sarcastic HVAC contractor who has real life experience, and who has chosen to not go into the duct cleaning business, and who generally believes that duct cleaning is unnecessary.
I remember as a kid, our original furnace was a creepy old oil-burning thing. It scared the crud out of me as a kid. There was a vent of some type on the front that sort of looked like a face that would constantly swing in and out like it was talking and you could see the fire through it’s “eyes”.
As a non-sarcastic HVAC contractor (appeal to authority much?) you should know that you need evidence to back up assertions. So, show me the science. That’s all I ask. I’ve provided mine, now show me yours. Just show me the numbers that disagree with what I’ve said.
I posted my experience and thoughts on the subject, and posters----particularly those who are familiar with posts I’ve made in the past on the subject of HVAC here at SBMB----are free to take my input or leave it.
It’s just that simple.
Lastly, I didn’t appeal to authority. I offered my opinion and experience on the subject, and the fact that I have 20 years as an HVAC contractor and that is entirely relevant as to how a reader evaluates my posts.
You’ve Googled up some stuff. Great. And made some bold comments from it. I offered another viewpoint that people are free to accept or reject. (and, it’s worth noting again that my viewpoint agreed with you in principle. It is my view that overstated your case. It is up to the reader to evaluate if your background supports your claim)