What Impact Does Closing Vents Have on an HVAC System?

Increased Energy Cost

• People used to live under the assumption that closing most of the vents in the home would save on energy costs. However, the California Energy Commission dismisses this as a myth on its website. In fact, it claims that the opposite is the reality. Because of the way that modern homes and duct systems are constructed, if you close off too many vents in a home, you actually cause problems that result in more wasted energy as opposed to gaining any net energy savings.

Leaking Ductwork

• When you close too many vents on an HVAC system, you run the risk of creating or worsening leaks in the system. This happens because the system has no way of knowing that a vent is closed. Therefore, it continues to push air down all the ducts, even those with a closed vent at the end. When the air reaches the end of the duct and can't escape, it increases the internal pressure in the ducts. This pressure is what forces air out of the system and causes leaks.

Overheating

• If you close too many vents on an HVAC system, you can cause your furnace to overheat. Open vents ensure that a steady stream of air flows throughout the HVAC system. The furnace in your house uses some of this incoming air to regulate its internal temperature. If too many vents are closed while the furnace is working hard, it may overheat and trip a safety switch that shuts off the gas to the furnace.

Equipment Wear

• Closing the vents on an HVAC system causes undue strain on some of the equipment. If you close too many vents, the system may sense that air is not being distributed adequately. This makes it work harder to compensate. In the end, parts like a blower motor or a fan can get worn out prematurely as a result of this kind of needless equipment strain. The furnace or air conditioner may also wear out more quickly as they work overly hard due to the decreased efficiency of a system with many closed vents.