How do I close off the return air vent?

Author: Cornelius Willms  |  Last update: Wednesday, November 12, 2025

Operable cold air return vents have a lever that enables you to open or shut the vent depending on the time of year. It is a small lever that you just push up or down to control louvers, similar to the variable dashboard vents in a car.

Can I block off an air return vent?

You cannot block a return without risking damage to your furnace. They require a specific amount of inbound airflow. Putting a return in a bay window is a pretty dumb idea, though.

Do return vents need to be sealed?

If they are too small, airflow will be restricted and there will not be enough air circulation to heat or cool the inside of your home. Return air ducts must be sealed and unobstructed — Sealing return air ducts is just as important as sealing supply ducts.

Should return vents be open or closed?

Hot air rises and cool air sinks. Therefore, opening the right return vents in the summer and winter significantly improves the distribution of air by your forced-air system. You'll also enjoy more even heating and cooling throughout your home. In the summer, open your high returns and close the low ones.

How do I close a return vent?

Operable cold air return vents have a lever that enables you to open or shut the vent depending on the time of year. It is a small lever that you just push up or down to control louvers, similar to the variable dashboard vents in a car.

The Proper Way to Close-off Air Conditioning and Heating Vents

Can you close off a cold air return?

Return vents are usually larger than supply vents and are in large rooms in the home. The return vents in your home help equalize the pressure that changes as your HVAC system heats or cools your home. These vents should never be fully closed because closing them off restricts airflow and strains the system.

What are the rules for return air ducts?

1. Openings shall not be located less than 10 feet (3048 mm) measured in any direction from an open combustion chamber or draft hood of another appliance located in the same room or space. 2. Return air shall not be taken from a hazardous or insanitary location or a refrigeration room as defined in this code.

How do you seal an HVAC return duct?

Step-By-Step Process
  1. Use foil tape to seal longitudinal seams along straight duct runs.
  2. Apply duct mastic with a paintbrush to joints where elbows connect to ducts.
  3. Measure and cut fiberglass insulation to fit around the ducts.
  4. Wrap insulation around the ducts, securing it with foil tape.

Should air be coming out of return vent?

Return vents tend to be bigger than supply vents, and you won't feel any air coming from them. When an HVAC system delivers air to a room, it increases that room's air pressure. Return vents exist to remove the extra air.

Is it OK to cover a return air vent?

While you should have a filter on your air return vent to prevent too much dust or moisture from entering your air system and recirculating back to you, you should never actually cover a return air vent. Keep furniture and even curtains at least 10” away from the vent opening in order to allow for proper air flow.

Why is my second floor so hot in the winter?

First, heat rises, so it's normal for the second floor of a home to get hotter than the main floor.

Should I close off unused rooms in summer?

See Also: Lower Your Energy Bill This Summer

To maximize the efficiency of your HVAC system as well as your comfort, don't close off unused rooms. Let the air flow through your home like it's designed to. Your air conditioner and your wallet will thank you!

What are the symptoms of not enough return air?

Symptoms include weak airflow and uneven cooling or heating throughout your home, with some rooms feeling much cooler or warmer than others. Homeowners should regularly check vents for consistent airflow. If you notice a significant drop in air pressure or uneven temperatures, it could indicate return air issues.

What happens if the return air vent is blocked outside?

Broken heating or cooling elements

On the heating side, if you block off the return, the exchanger can overheat. “In extreme examples, it can crack and fail,” Smith says. “They're all designed to have that proper airflow and bad things can happen when that's thrown out of whack.”

How do you block an unused air vent?

Place a piece of tall furniture in front of the wall vent to hide it. Alternatively, hang small pictures, awards, or floating shelves in front of the air vent. For a more permanent solution, install a drywall vent cover that matches the design of your home.

How do you close return vents?

In many homes, the HVAC vents have fins that can be adjusted with a sliding switch. These fins can be used to direct airflow at a particular angle, but if you push the switch all the way to the side, they can be used to close off the vent entirely.

Can I block an AC return vent?

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.

Does return air need to be sealed?

All supply- and return-duct connections should be sealed with mastic or approved tape. Because ductwork in cavity spaces is likely to be inaccessible, the duct system for airtightness should be tested with a duct-blaster test before installing the drywall.

What is the code for return air?

Return air openings for heating, ventilation and air-conditioning systems shall comply with all of the following: Openings shall not be located less than 10 feet (3048 mm) measured in any direction from an open combustion chamber or draft hood of another appliance located in the same room or space.

What happens if there is no return air duct?

If there's not enough return air, your living room can be 10℉+ warmer or cooler than, for example, the bedrooms. Not enough return air in summer can cause rooms close to the central unit to be cooler and those farther from it to be warmer. In winter, rooms farther from the furnace can be too cool.

Does every bedroom need a return vent?

Does Every Room Need Air Return Grilles? While it is a myth that air return grilles are required in each and every room in the house, it is definitely necessary to have more than one of these grilles installed at strategic places in the house. The most important place to have these would be the bedroom.

Why is my return blowing cold air?

Dirty filters, leaky ducts, and poor insulation can cause cold return vents. Leaky ducts often cause cold air to blow even after cranking the heat up. 20-30% of air, especially hot air, is lost because of leaky ducts. Cracked, holey ductwork needs sealing or replacement.

Should cold air return vents be up or down?

When it comes to cooling your home, return vents are best installed near the ceiling so they can draw in any hot air that has risen. Supply vents should also be placed high on the wall for better distribution of cold air throughout the room.

What happens if you block the air vent?

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.

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