"Energy is consumed by HVAC systems through a number of processes. Air is typically distributed through the ductwork via an electrically‐powered fan. Cooling coils remove heat from the air. Heating coils add heat to the air. Through normal HVAC usage, particulates in the air slowlycollects on the surfaces of various HVAC components, resulting in a gradual loss of energy efficiency. Some loss of efficiency via a single dirty component may be minor. When the loss through each component is added up, however, the impact could be considerable. Generally, the greater the buildup, the greater the energy loss. Removal of the buildup of particulate on HVAC components restores energy performance to the system." 
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.
"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."
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