If your air ducts have been damaged, you’ll need to replace them. The national average air duct replacement cost is $150-$280, which may not include materials. Factors such as duct material, labor, location of ducts and linear feet of ductwork will all affect your final costs. Labor costs will vary based on how accessible the ducts are and what material your ducts are made of. The least expensive duct material is a flexible, non-metallic ducting that costs approximately $1-$2 per linear foot. Flexible aluminum is generally more expensive and stronger than non-metallic ducting. Stainless steel ducting is the strongest, the least flexible (meaning installing it typically has higher labor rates), and usually the most expensive. An average price for air duct replacement could range between $35 and $55 per linear foot, including basic materials and labor. A typical single-family home has 6-10 duct runs; replacing or installing one duct run could average $150-$250 for labor.

The best way to know if your cleaning was effective is through improved performance of your HVAC system, ideally. You can have before-and-after pictures taken of the ducts (make sure they are of the intake ducts - the ducts that return air into your room), motor and coils. Another tip is smell – sniff the ducts before and after the work is done. Outside of noticeably improved performance, smell and visual evidence are your best indicators.
Under normal conditions, standard-use residential ducts (HVAC systems) should be cleaned every three to five years. Usage, system age and condition, local air quality, and number of residents and pets can affect cleaning frequency needs. Harsher conditions might require cleaning as often as every two years. Obviously, if your system is not functioning properly or the output air quality is bad, consult a professional sooner rather than later to get a proper diagnosis.
"So My A.C. suddenly went belly up and I needed a total brand new unit inside and out. So a little background on myself. I'm an engineer, so I know a little bit about A.C. and how they work. I'm by no means an expert, but it does allow me to detect if the A.C. guy knows his stuff, especially if they don't know what I do. 😉 And I'm happy to say, these guys do. One of the things that helped me chose them is that they brought up the importance of controlling humidity. None of the other contractors I spoke to, mentioned that. I also appreciate the fact that he didn't try to "up sell" me and get me to buy things I didn't need. He was on time, honest and forth coming about what I needed and what I didn't. When the workers came, they were on time, very professional and very CLEAN. After they left, I couldn't tell they had been there. Highly recommended this service."