Can I Close AC Vents in Unused Rooms to Save Money?

If you usually use only a few rooms in your home, you may think that closing off a few vents will save money. In reality, closing off vents will not reduce the amount of work your air conditioner needs to do. In fact, it may cause your AC unit to work harder.

The Role of Vents in Home Air Distribution

Supply vents allow cooled air from the air conditioner to circulate throughout the home. Many supply vents are registers with levered handles, allowing homeowners to open and close them as needed. When you close one of these registers, the amount of air flowing through your ductwork does not decrease. Instead, air will hit the slats of the register. Air may escape through the cracks in the register, redirect to other vents, or leak from the ductwork.

Closing Air Vents Increases Pressure on the System

When you close air vents and redirect air throughout the ventilation system, the amount of pressure in the system increases, forcing the blower (the part that moves cooled air through the system) to work harder and less efficiently. Increased pressure inside the ductwork/HVAC system can cause serious problems.

Problems That May Arise from Closing Air Vents

Consider some of the problems that may arise when the pressure increases in the HVAC system:

1. Worsening air duct leakage. Increased pressure forcibly redistributes the air inside the duct system. Since most residential duct systems are not sealed, the air will escape through cracks and effectively air condition your attic.
2. Decreased energy efficiency. Some blowers adjust according to airflow needs. Other systems use a basic opened/closed system. The first type of blower will work harder to maintain temperatures and airflow in the presence of increased pressure. The second type of blower does not have the ability to work harder. It may simply work less efficiently and deliver poor airflow through the open registers in the home.
3. Frozen air conditioner coils. Many systems are considered fixed-capacity systems. The coil and heat exchanger can only absorb or distribute a certain amount of heat. During times of inefficient airflow, the coil may not absorb enough heat to keep it running smoothly. In the absence of heat, the coil may grow cold and develop frost in the same way a refrigerator coil may freeze over. Ice on the coil will further decrease the airflow efficiency.
4. Damaged heat exchanger. Low airflow will cause the heat exchanger to get hot enough to crack. Cracked heat exchangers can leak harmful gases, such as carbon monoxide, into your home.
5. Mold buildup. When airflow decreases and condensation builds in any part of the HVAC system, vents, air ducts, and the central unit may start to develop mold.

Contrary to what you might think, cutting off the air supply to a few rooms will not help lower your energy bill. To save money, consider using other energy saving tips, such as lowering the thermostat settings during winter and raising them during summer.

If you’re looking for new ways to save money on your cooling and heating costs, contact the HVAC experts at Amber Air Conditioning Inc.. We would love to discuss the money-saving HVAC upgrades that are available to homeowners.