Venting the Truth
Closing air vents in less-frequented rooms doesn’t reduce the total airflow produced by your HVAC system. Instead, it simply traps that air and increases static pressure inside the ductwork, throwing off the system’s carefully balanced design. Over time, that excess pressure causes the motor blower to work harder, raising the risk of duct leaks, frozen coils, and costly compressor damage.
Don’t just take our word for it — the U.S. Department of Energy warns that closing more than 20% of your home’s vents noticeably reduces system efficiency. Doing so can cause uneven temperatures in the rooms you actually use, damage your equipment, and even trigger health risks such as mold growth or increased radon levels — the latter of which is the second leading cause of lung cancer.
Beyond those health concerns, leaks caused by trapped pressure allow conditioned air to escape into your attic or crawl space, forcing your HVAC system to work overtime and spiking your utility bills.
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What To Do Instead
Instead of closing vents in unused rooms, you can take safer steps to limit energy use. One of the most effective methods is adjusting your thermostat when you’re sleeping or away from home. Set the temperature 7 to 10 degrees higher during warmer months and 7 to 10 degrees lower in colder months for eight hours a day. This simple adjustment can save up to 10% on your annual heating and cooling costs.
You should also seal any leaks or gaps where conditioned air may be escaping. Exterior doors and windows are the most common culprits, but a simple 30-second draft test will quickly reveal where those leaks are coming from. Sealing those gaps lowers your energy bills without compromising the integrity of your HVAC system.
