Why Closing Air Vents in Unused Rooms Damages Your HVAC System

Ever wondered if you could save money on heating and cooling bills by closing the air vents in unused rooms? Unfortunately, this is a common myth that can cause a host of problems like increased energy bills (ironically) and even system failures.

Healthy airflow in your home requires the even distribution of warm or cool air into each room, along with the intake of air through your air duct network. If something blocks the flow of air (such as a closed vent), it will impact the pressure dynamics of your HVAC system, putting undue strain on your heating and cooling equipment.

To further explain why closing air vents in unused rooms can damage your HVAC system, let’s review:

Air balancing is carefully measuring and adjusting airflow to keep air circulating in each room. This helps to properly distribute warmth or air conditioning to avoid uneven temperatures or drafts that could make your home uncomfortable. Also, air balancing carefully keeps the pressure inside your ductwork balanced.

To avoid poor airflow, you want to keep your vents and intakes open and unobstructed by furniture, rugs, piles of laundry, or pets. A misdirected airflow may mean adjusting the vent louvers to prevent pressure buildup inside the ducts.

Airflow problems caused by blocked or closed vents are also unhealthy for your home’s heating and cooling system. The wrong static pressure in your duct system can damage your equipment or even cause it to fail. These problems can arise when static pressure and other airflow values are unpredictable. Your home’s ductwork is carefully designed to work optimally and help your HVAC equipment last as long as possible.

Your home’s HVAC system uses an air handler with a blower motor that manages airflow. It pushes air against a calculated resistance of your ductwork. When vents are blocked or closed, the pressure can rise and cause a breakdown of the motor. If the pressure causes a rupture in the duct system, the motor might wind up pressing against too little resistance due to the broken ductwork. Either way, you’ll need to have the blower motor checked and possibly replaced. Any belts used to run the fan may need attention as well.

Did you know that a clogged air filter can cause harm to the AC evaporator coil? The evaporator coil is a cold part that warm air blows over. As the air passes over the coil and is cooled, moisture naturally condenses and runs off, dehumidifying your air as well.

What happens if the airflow is too slow? The condensate ends up freezing over the coil. After a considerable waiting period for the ice to thaw, contact a technician to check for damage.

Just as the evaporator coil has a delicate balance of cooling based on airflow, your furnace’s heat exchange also depends on the right amount of air passing through. An insufficient airflow rate allows the heat exchanger to overheat by not removing enough heat, causing cracks. A cracked heat exchanger is a dangerous problem as it can lead to carbon monoxide and other gasses circulating throughout your home.

Like everything else in your heating and cooling system, your ducts are carefully designed for the right airflow and pressure. Variations in either of these values can stress your ducts, leading to breaks in the seals and leakage. The type of leakage may vary depending on the type of ductwork you have, which can be metal, plastic, or other materials. Duct leaks may require repairs or replacements. If your ducts are in difficult-to-access spaces, like your attic, the labor cost goes up.

With improper airflow, you could experience higher energy bills, even if you were trying to focus your heating and cooling in a specific part of the house. Our technicians can install a zoned ductwork system that manages separate temperatures while allowing proper airflow.

You’ll also experience decreased comfort due to abnormal air balance conditions in your home and its rooms. Hot or cold spots will develop where the airflow is unbalanced, and rooms with unblocked vents will receive more heating or cooling than expected. If you’ve closed the vent in the room with a thermostat, the rest of the house will get more heating or cooling than you wanted.