fake security cameras
Typically a shop vac hose can only reach up to 15’ before
the hose just curls up. Some trunk lines may stretch out to over 100’ in distance, which means 15’ would be cleaned and 85’ would go untouched. 90 degree turns will almost always make the shop vac end its descent in cleaning down a pipe
because the shop vac hose cannot be turned without physical intervention. A greater risk of disconnecting pipes occurs due to the physical nature of the contact cleaning method. Also if any home security wiring, telephone wires or low voltage wiring is ever present in the ductwork, the physical nature of the contact cleaning method in air duct cleaning will increase the chances in breaking such wires, whereas air washing will not compromise such wires in any shape way or form. Most contact cleaning companies will recommend that you should have your air ducts cleaned out every year or two, because they know they left enough debris in the ductwork to try to get at it again in a year or two.