How does duct leakage affect heating system efficiency?

• A. It causes conditioned air loss, increased energy consumption, and reduced comfort.
• B. It improves airflow and increases efficiency.
• C. It has no impact on energy use.
• D. It reduces system pressure but improves comfort.

Answer: (A)

Duct leakage wastes energy by letting conditioned air escape before it can do its job. When the blower pushes air through the ductwork, any holes or gaps in the ducts mean some of that air leaks into attic, crawlspace, or walls instead of the living spaces. That reduces the amount of warm or cooled air reaching the rooms, so the system has to run longer or at higher speed to try to meet the thermostat setting. The result is higher energy use and higher utility bills.

Leaks also disturb the pressure balance of the system, which can pull return air from unconditioned spaces and create drafts or uneven temperatures, making the home feel less comfortable. In short, duct leakage decreases delivered airflow efficiency and comfort, whereas sealing and insulating the ducts helps the system reach the desired temperature more reliably and with less energy wasted.