Should I replace all my air conditioning ducts?

Lynn C.
by Lynn C.
The insulation and covering on several of my air conditioning ducts are completely gone. The ac company wants to install a complete new duct system costing several thousand dollars. Is this a good idea or should I just repair those that are in need which will cost around $700. Thanks.
  8 answers
  • J & J Refrigeration J & J Refrigeration on May 29, 2013
    It depends if duct system is flexible duct work or duct board, then yes replace. But if ridged duct work, covered by insulation then reinsulate.

  • H.O. Electric H.O. Electric on May 29, 2013
    New duct work if installed properly will make your system more efficient. as a result, save money. New duct work will be cleaner than your old. You will breath easier knowing it is clean.

  • Billie Walls Billie Walls on May 29, 2013
    I agree with J & J's recommendation, If it is metal duct, then reinsulation is fine ( metal duct lasts forever) and if it is flex duct then replacement is cheaper than trying to repair. And if breathing easier is your main objective,, I would have my metal duct system cleaned after the insulation repair and it will still be cheaper than replacing the whole duct system. Hope this helps.

  • A1tec service A1tec service on May 29, 2013
    sent you live Fl it would be best to replace what is bad now if it metal and the age of the ductwork it best to replace it due to mold and dust having it clean will not get all dust .and if it ductboard clean it will break the film on the ductboard then you will insulation going in to your house

  • Miles Enterprises Inc. Miles Enterprises Inc. on May 29, 2013
    If the ductwork is metel repair and reinsulate. If it is flex duct start over. if you have made other changes to your home like turning the room over the garage a bous room. then start over.

  • Lynn C. Lynn C. on May 30, 2013
    Thanks so much for your imput!

  • If the ducts are metal, re-insulate. However prior to doing that use duct mastic and seal every joint and hole in the ducts. This will help prevent air loss and increase the efficiency of the system overall. If your home has cooling issues when its hot, I would suggest that the contractor do two things. 1. Do a manual J heat load on the house to determine if the size of the system is correct for the home. Many systems are oversized and that is costly to you and can cause discomfort in the way of excessive humidity. 2. Do a manual D duct sizing on the house. Once you are sure your current system is correctly sized then you can check the current size of the ducts to what the report findings suggest. Manual D will determine exactly what size ducts are required to deliver the correct amount of air to each and every room. If they are incorrect and sometimes they are, you may want to change a few or just one to make the system perform better. Once both of those things are done and the proper equipment and duct sized are installed. Then you should insulate the ducts with at least 2" of foil back insulation to assure against condensation. It is very important that the outside foil vapor barrier be properly sealed to prevent condensate from forming and the possibility of mold development. Try to limit the flex ducts as much as you can. They are impossible regardless of what duct cleaning companies tell you to properly clean. And the longer they are the worse the air flow coming out the other end. Do NOT use any duct board or interior duct lining on the system. The liners and duct board are made of fiberglass and if not done properly will result in fibers being released into the air. Not a good thing.

  • Jay Taylor Jay Taylor on May 26, 2014
    Nice blog! If your air conditioner needs immediate repair then you should change the entire duct but if it is considerable then instead of repairing you can opt replacing as it will take less time and will be more economical. Thanks for asking this question as it will help many clear their confusion.