How to fix excessive condensation dripping from A/C vents & ductwork?

Mewickman
by Mewickman
  5 answers
  • C. D. Scallan C. D. Scallan on Jun 21, 2017

    Chances are that they're dripping because they're clogged and need to be cleaned out.

  • William William on Jun 21, 2017

    HA HA! Clogged, Clean?!


    If the condensation is dripping from the register, there is either a leak around the duct boot which the temperature differential from the attic and supply air is condensating or the there is a break in the supply duct and is condensating down the duct into the boot and onto the register.


    You need to check the area around the boot at the sheetrock. Seal the cracks around the boot under the grill with caulk or duct sealant. Also check the connection of the duct to the back of the boot for leakage.


    Add insulation! Bare sheet metal is the worst case scenario, but any uninsulated ductwork needs to be addressed. Buy insulation in batts or blankets and begin snugly but not tightly wrapping your ductwork. If your wrap it too tightly or compress it with duct tape then you will reduce it’s R-value, defeating the purpose. Again, reading What Type of Insulation Should I Use is a good place to start for information on R-values and different types of insulation. The insulation you use to wrap your ducts should leave no gaps and be at least two inches thick to work effectively at reducing or eliminating condensation on ductwork.


    Also make sure to use HVAC tape and seal all of the joints between duct segments. No air should be able to penetrate the ductwork and the joints are a natural weak point.


    Another problem that needs to be addressed it the natural moisture in the air. The most common cause for this is inadequate ventilation in your attic. Your attic has vents for a reason! If there is inadequate ventilation in your attic, then contract your local roofing contractor for information on adding roof vents. Otherwise, moisture will build up and you can face possible mold problems in your attic.


    The next step is to ensure that you add a vapor barrier to your ductwork. Most modern ductwork comes standard with insulation and a vapor barrier, so my recommendation would be to just replace your ductwork. However, special attention should be given if your ducts do not. Add a vapor barrier by buying vapor barrier wrap available at Lowe’s and other hardware stores and following the directions included. It will consist of covering every area of your ductwork with at least one layer of wrap.


  • FL FL on Jun 21, 2017

    Here is a web site with some troubleshooting excess condensation: https://hvac4u.wordpress.com/2012/05/03/window-air-conditioner-leaks/  ; Hope this helps!

  • Mewickman Mewickman on Jun 21, 2017

    Thank you all for your help. We'll be making a trip to the home improvement store sooner rather than later.

  • FL FL on Jun 22, 2017