I love this subject especially since it has been a very hot topic on social media. By now we have all seen the "scare tactic" posts by individuals and companies alike on Facebook showing all the nasty stuff inside a duct system. Along with these posts, they claim that cleaning the ducts improves indoor air quality as well as the efficiency of your hvac system. Before we go much further I want to share a link from the EPA found here https://www.epa.gov/sites/default/files/2014-07/documents/airducts.pdf as I will reference this study performed by the EPA throughout this article.
I was sold to at one point that this is a beneficial service that everyone needed so I as an HVAC contractor I went and bought a very expensive duct cleaning machine and anti fungal fogger. I saw no measurable benefit that would justify the price unless someone had extremely nasty ducts. I decided to start digging for information and see if anyone had conducted studies as far as before and after duct cleaning to quantify the benefits. I found that the EPA as well as the California Air Rehab Board (CARB) both have. The EPA study was easier to read and understand which is why I stick with it. To understand why duct cleaning could be necessary, we need to ask ourselves why? What problem are we trying to solve? The Facebook ads I saw all claimed to increase indoor air quality, but the EPA actually studied this and found that there was no measurable benefit in terms of indoor air quality after duct cleaning services. Matter of fact, that's the highlighted fact discussed in the link I included above. Well... if duct cleaning doesn't increase the quality of the air in the home, will at least increase the efficiency of the hvac system?
The systems where I cleaned the ducts where all long time clients of mine so I have the privilege of historical performance data for their systems and how they operated. I found that there was no measurable performance in the systems. The idea behind this claim is that by removing debris from the inside of the ducts, we get better airflow and thus the system works better. A competent professional in my industry would quantify this by measure the external static pressure of the duct system. The static pressure is basically a way to measure the resistance to air flow inside a duct system. My own tests have shown no change in the operating static pressure of a system after having the ducts cleaned.
I see duct cleaning no different than dusting/cleaning the surfaces of your home. The dust sitting on a book shelf is not going to kill you, nor will the dust in your duct work. In extreme cases where dust/debris buildup is obvious and in large quantities, I think duct cleaning has its benefits. Doing heating and air conditioning for 20 years now, I can say that I personally have never come across a system that was "filled" with dust. The constant air being moved through the ducts will typically alleviate large accumulations.
My recommendation would be to first determine why you are concerned about dirty ducts. If you think you have dirty ducts causing poor indoor air quality, purchase an indoor air quality monitor of decent quality online and track the readings. A recommendation is to get one that has good resolution in the PM2.5 range, meaning it detects particulate matter concentration 1/4 the width of a human hair. You may be surprised to find that your indoor air quality isn't necessarily bad at all in which case duct cleaning wouldn't really be beneficial. I would also recommend a visual inspection of the ducts. If you see obvious large accumulations, then duct cleaning may be a consideration.
The scientific community utilizes a process of analysis and testing prior to implementing a solution and I view every issue in life exactly the same way. If we throw random solutions at unknown problems, the probability of success is anywhere between 0% and 100%. Basically it's a guessing game. I hope this helps and as always feel free to comment as I love to hear feedback. Thank you for reading.
Kenneth Casebier
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