There are several schools of thought on indoor air quality, but we’re of the school that relies on official unbiased guidelines for determining when ducts should be cleaned. The National Air Duct Cleaners Association (NADCA) has a guideline, NADCA ACR 2013 Assessment, Cleaning and Restoration of HVAC Systems. This guideline is available for free from the NADCA website. The standard explains that It is highly recommended that HVAC systems be cleaned when an HVAC cleanliness inspection indicates that the system is contaminated with a significant accumulation of particulate or if microbial contamination………… NADCA advises a competent inspector carefully evaluate the duct system and major HVAC components on according to Table 1:
The US EPA has also come out with guidelines to help homeowners decide when to have their ducts cleaned. Here are some excerpts from Should You Have the Air Ducts in Your Home Cleaned, by the EPA:
“You should consider having the air ducts in your home cleaned if:
- There is substantial visible mold growth inside hard surface (e.g., sheet metal) ducts or on other components of your heating and cooling system.
- Ducts are infested with vermin, e.g. (rodents or insects); or
- Ducts are clogged with excessive amounts of dust and debris and/or particles are actually released into the home from your supply registers.”
It may come as a surprise to many that the EPA and NADCA do not recommend routine duct cleaning unless rather significant problems are discovered during an inspection. If there is active mold growth, infestations, or dirt accumulation hindering the performance of the HVAC… you’ve got problems!
So if you’ve really got a problem… will duct cleaning help improve IAQ? The sad truth is duct cleaning – done the wrong way – can cause more problems than it solves. There really is a “right way” of duct cleaning, and the control measures spelled out in the NADCA ACR standard minimize the risk of cross-contamination. The last thing you want is for the contaminants (mold, animal feces, excessive dirt) leave the ducts and contaminate the rest of your living space. The control measures are all about limiting the use of biocides and controlling fine particulate.
Therefore, when you want AC duct cleaning, always use a NADCA certified company, like us!
Healthy Building Science – http://healthybuildingscience.com/