I was looking for opinions acefurnacefixer
as many others, including the US EPA say it is not
necessary. Here is an excerpt from an EPA report :
......."Knowledge about the potential benefits and possible problems of air duct cleaning is limited. Since conditions in every home are different, it is impossible to generalize about whether or not air duct cleaning in your home would be beneficial."....
..."If no one in your household suffers from allergies or unexplained symptoms or illnesses and if, after a visual inspection of the inside of the ducts, you see no indication that your air ducts are contaminated with large deposits of dust or mold (no musty odor or visible mold growth), having your air ducts cleaned is probably unnecessary. "
A third excerpt
.......".if a service provider fails to follow proper duct cleaning procedures, duct cleaning can cause indoor air problems. For example, an inadequate vacuum collection system can release more dust, dirt, and other contaminants than if you had left the ducts alone. A careless or inadequately trained service provider can damage your ducts or heating and cooling system, possibly increasing your heating and air conditioning costs or forcing you to undertake difficult and costly repairs or replacements."
I have looked into the 6" supply pipe I cut & find no large deposits that aren't simply blown out when the furnace kicks on at the begining of the heating season.
The full EPA report is here:http://www.pueblo.gsa.gov/cic_text/h...s/airduct.html