No, you should never completely block or close active supply and return vents in the winter. Blocking airflow alters the pressure in your ductwork, which forces your heating system to work harder. This can cause cracked heat exchangers, damage the blower motor, freeze coils, and drive up your energy bills.
No, you should generally not close air vents in winter. Closing vents in unused rooms does not save energy. Instead, it restricts airflow, forcing your heating system to work harder. This can spike your electric bills, damage your furnace, and lead to frozen pipes.
Because your home's HVAC system is designed to regulate the temperature of the entire house, when ducts are closed, this pressure can build up and may eventually cause damage to your ducts or heating system. To sum it up, closing your air vents may mean that: Your HVAC system must work harder.
Blocking an air vent disrupts your HVAC system's airflow. This forces the blower motor to work harder against increased air pressure (static pressure). It often leads to expensive system damage, uneven room temperatures, and a higher risk of mold or moisture buildup.
*Any reduction in the temperature of your home from a trickle vent is very marginal and unnoticeable. If you are concerned about your home feeling cold, it is likely something else and not your trickle vents causing the issue. Take a look at our 5 simple steps to make sure your home is winter ready.
Signs your home's humidity is too low may include:
You should never completely block a cold air return. Blocking returns chokes your HVAC system of necessary airflow, causing it to work harder, consume more energy, and potentially suffer premature motor failure or a cracked heat exchanger.
Use cardboard. Paper won't hold against the air pressure. Those vents just screw on and off. You could unscrew it, pull it down, cut a piece of cardboard to fit the opening, then screw it back up there.
Cold air return vents should always remain open in the winter. Closing them restricts airflow, strains your HVAC system, and lowers heating efficiency.
A build up of pressure can be caused by covered vents. This could lead to a cracked heat exchanger which in turn can lead to leaking carbon monoxide. 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.
When you close vents, you disrupt this airflow, causing uneven heating in your home. Increased pressure: When vents are closed, air pressure increases in your ductwork. This increased pressure can lead to air leaks as the excess pressure forces air out of cracks and seams in your ducts, leading to higher energy costs.
The $5,000 rule is a guideline to help homeowners decide whether to repair or replace their HVAC system. You multiply the age of your unit by the cost of the needed repair. If that number exceeds $5,000, replacing your HVAC system is often more cost-effective.
Attic fans have fallen out of favor because they often do more harm than good. They create a "negative pressure" zone that can suck conditioned, expensive air out of your living space and pull dirty air, moisture, and allergens into your home. Additionally, they consume excess electricity and require regular maintenance.
No. Closing vents in unused rooms in the winter actually wastes energy and can damage your HVAC system. Your central heating system pushes a set volume of air regardless of open vents; restricting it forces the system to work harder, increasing wear, system strain, and the risk of duct leaks.
Yes, mice can easily crawl through vents and ductwork. Because their skulls are highly flexible, a mouse can squeeze through any opening that is just the size of a nickel or a pencil (about 14one-fourth14 to 38three-eighths38 of an inch).
Why it's not a fire hazard House vents don't get hot enough to ignite cardboard. Typical forced-air heating systems put out warm air (usually 40–60°C / 100–140°F). Cardboard needs well over 200°C / 392°F to even begin to burn. The cardboard is not touching any open flame or heating element.
Lüften, which translates to “airing out” in German, is common practice because the country's homes are very well-insulated, and opening windows is thought to reduce mold, humidity, pollutants, and odors.
If your home has top and bottom style return vents, you can help even out the heat in the house by closing the top vents in the winter months. Closing the top vents will force your HVAC system to draw in air from the bottom vents, which are located at the low point in the room where cold air settles.
You should not place a couch directly over or tightly against a return vent. Blocking these vents restricts necessary airflow, forcing your HVAC system to work much harder, and can lead to higher energy bills, a frozen evaporator coil, or premature motor failure.
Less reach: You may find that your cold or hot air from the air conditioner or furnace does not get as far as it should when your air vent is blocked. Your home's temperature may feel inconsistent, with hot or cold spots. Stagnating air: With reduced airflow, you will have stagnated air through the home.
Despite its name, duct tape is not meant for air ducts.
Even one blocked vent in the home can cause an inefficiency in air flow, which means your HVAC system will likely have to work harder to achieve the desired temperature. The result may be a home that is riddled with uneven temperatures from room to room.
But here's the twist: closing vents can backfire, causing more harm than good for your system. ❌ Closing vents won't save energy. 💡 Instead, it disrupts your A/C system's airflow, increasing pressure in the ducts and causing inefficiencies. ✅ Keep all vents open to maintain your system's designed airflow.
One of the most surprising places they can hide? Your ductwork. That's right: your heating and ventilation system may be more than just a pathway for warm or cool air; it could also be a cozy travel route (and nesting spot) for mice.
Covering a return vent starves your HVAC system of the airflow it needs to function properly. This creates immense strain on your blower motor, decreases heating and cooling efficiency, and can cause the system to freeze up in the summer or overheat and crack the heat exchanger in the winter.