duct problems

Duct problem areas

Ductwork problems. (A) Leaky duct connection. (B) Return leaks. (C) Furniture blocking register. (D) Leaks at furnace and filter slot and duct tape failure. (E) Fallen duct insulation. (F) Supply leaks. (G) Kinks in ductwork restricting airflow.

The duct system in a home can suffer from a number of problems that prevent it from evenly heating and cooling the living space.


  • Poor design. A well designed duct system minimizes the length of ducts and number of bends, is sized correctly and places ducts within conditioned spaces. A poorly designed duct system means your furnace or air conditioner has to work harder and use more energy to get air to every room to keep you comfortable. If the duct system installed in your house was poorly designed or your house has changed from the original design your duct system may need to be modified to correct the problem.

  • Poor duct installation. Sometimes the duct system is designed well, but it is not installed well. Most duct systems leak air because the installer did not seal the leaks. The more air that leaks out the more energy it takes to heat and cool your home. Another common problem is ducts in an attic or crawl space that are not insulated. Overtime, duct insulation may fall off if not properly installed. Flexible ducts come with insulation and make the installation easier, but kinks in the duct will restrict air flow, and if connections are not sealed air leaks out.

  • Unbalanced ducts. An unbalanced duct system doesn't sound good and its not. Most duct systems have never been balanced and others have been improperly adjusted. The result is that the right amount of air is not going to each room and it takes more energy to keep you comfortable. A heating and cooling contractor can modify or adjust your ducts to evenly heat and cool every room in your home.

  • Not enough air returns. A common design in many homes is a centrally located air return. Unfortunately, closing doors to rooms can cut off the supply of air to the return and create a pressure imbalance. A better design is to install a return duct in every room that has a supply duct.

    Many of these problems can cause pressure differences between rooms or the inside and outside of your house that cause air leakage from the outside that your feel as cold drafts in the winter. A heating and cooling contractor that specializes in duct repairs can recommend solutions to solve many of these common duct problems. The contractor will use special diagnostic equipment to determine duct pressures; air flow and leakage that help determine the efficiency of your duct system and prescribe improvements.