Hi Bob,
Yes we have done a few duct cleaning jobs. We recently purchased a 5000 cfm HEPA unit. Most all of the equipment manufacturers have videos about there equipment and some training.
NADCA (National Air Duct Cleaners Asso)http://www.nadca.org may be able to direct you to classes. I attended a few different classes many years ago.
One of our larger accounts asked us to clean some ducts for them. At first I used a sub contactor, since I did not have any equipment. The job that we just completed with our equipment was a 5 story building with 8 bathroom/shower exhaust systems. We cleaned all of them in 3 days with a 3 man crew.
Dave Olson
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Tidy Powerwash Service, Inc. P.O. Box 781, Catlin, Illinois 61817 Phone 217-427-5557, Fax 217-427-2632 We are a commercial cleaning contractor serving East-Central Illinois and West Central Indiana since 1984.
http://www.tps-inc.com/preswash.htm