The quick answer is, Yes, it is OK to close air vents. But it's not recommended, especially if you close multiple vents all of the way and keep them closed.
Closing air supply vents increases the air pressure inside the air ducts, which backs up into the ductwork of the home and can cause leaks.
No, it won't damage the system. But closing vents, closing doors, blocking return air vents will cause high and low air pressure zones within the house.
A blocked air vent can permit mold or mildew to develop in and around your vents and ductwork if you reside in a humid location. You can be wasting money on utility costs. You most likely thought covering your air vents would certainly save you energy, but it does the opposite.
Contrary to what most people think, closing the vents in a room doesn't divert that air to other rooms. What's actually happening is that air will leak from the ductwork, sending cool air into areas such as interior walls and attic spaces.
Close top return vents.
Closing the top vents will make your system draw in air from the bottom vents that are at the low point in the room where cold air settles. (Hint: In the summer months, open the top vents and close the bottom ones to draw out air from a higher point in the room where it's hotter).
Another problem you might have could be dirty air vents. Dirty air vents can block air from getting through just like objects can, and they could be the answer to your question of “Why is it so cold in my house?”
We've seen how it can create safety hazards, mess with your home's heating and cooling, and even damage your bed. Blocked vents can cause fire risks, poor air quality, uneven temperatures, and moisture buildup. Instead of covering vents, try rearranging your furniture or using vent deflectors to direct airflow.
Closing air vents can lead to increased pressure in the ductwork, damage to the HVAC system, mold growth, and safety hazards, such as carbon monoxide infiltration. It's best to keep the air vents open to prevent these risks.
Proper installation improves energy efficiency.
It protects your indoor air quality. Aside from worrying about the damage on your wallet, unsealed air ducts could lead to poor indoor air quality. Pollutants can enter your ductwork via the subpar seals and cause health problems, such as asthma or outdoor allergies.
When you close off the vents in a room, you are completely blocking airflow to that space. That's the point right? Here's why it is a problem: If that air isn't passing through the vent, it is being backed up in the ductwork, which causes pressure to build up within the system.
Reduced efficiency: Your HVAC system will work less efficiently if you block a return air vent. This will make the units use more energy and will raise your utility costs.
Although closing off unused rooms may seem like a way to save energy on heating and cooling, it can actually force your HVAC system to work harder. In order for your air conditioner to work efficiently, you should keep the interior doors in your home open as much as possible.
Closing air vents can cause your HVAC system to work harder and reduce its efficiency, costing you more to heat and cool the home while also reducing the lifespan of the unit.
Avoid blocking air vents with pillows, furniture, plants, or pictures. When the air vents are blocked it means that heated or cooled air needs to squeeze by what is blocking it to reach the rest of the room.
AC Vent Open or Closed: What Experts Recommend
Balanced Air Pressure: Keeping vents open maintains balanced air pressure in your ductwork, allowing your HVAC system to run more efficiently. Consistent Temperature: Open vents help achieve a uniform temperature throughout your home, enhancing comfort in every room.
Static pressure in your air vents
Static pressure is the resistance to airflow in your HVAC system. These systems are designed to have the right balance of static pressure. Closing vents will increase the pressure, which can restrict or stop efficient airflow in your home.
Many customers believe closing vents in unused rooms is best, thinking it saves energy. But here's the twist: closing vents can backfire, causing more harm than good for your system.
Shutting Heating Vents in the Summer to Conserve Energy
Leaving vents closed for extended periods can cause damage and expensive leaks. That's why we recommend rotating which vents you close every few days. Doing so will help keep your HVAC system in great shape and lower your monthly energy bill.
You run the risk of causing damage to the heat exchanger
A buildup of pressure from air being pushed to covered vents can cause difficulties with your heat exchanger, causing it to shatter and release carbon monoxide into the atmosphere.
You will probably see one of two things - a gap between the inner and outer skins of the walls or the equivalent to a duct to the outside. If there is a gap between between both skins then you should be ok to cover up the inner skin. if it is the equivalent of a duct then I would block up the outside as well.
Block Off the Vent: You can block the vent by placing a piece of furniture at the opening or purchasing a magnetic damper that's strong enough to stick to the steel on the wall or ceiling. Plastic sheeting can be placed over the opening as well. You can also install a vent grille filter.
Closing vents disrupts the airflow balance in your HVAC system, forcing it to work harder to maintain the desired temperature. This added strain can lead to a malfunctioning heating system and unnecessary wear and tear, reducing the system's lifespan.
Common issues like leaks, disconnections, or obstructions within the ducts disrupt the flow of cooled air, causing rooms farther from the HVAC unit to suffer the most. In some cases, inadequate insulation of ducts can allow heat to infiltrate, further exacerbating the problem.
Covering your vents can damage your HVAC system and cause cracks that could allow air to escape your ducts. This can lead to higher energy bills. Furniture should be approximately 18 inches from furniture. It's important to make sure the air in your home flows freely.