What vents should be open in winter?

Author: Prof. Marjolaine Greenfelder DDS  |  Last update: Saturday, January 24, 2026

Here's what to do:
  • In colder months, close supply vents in higher locations, like up by ceilings, while opening lower ones on floors or close to baseboards. ...
  • In warmer months, do the opposite — open the supply vents in higher locations and close the ones placed lower.

Which vents open in winter?

Conversely, in the Winter heating season, you will want to pull the coldest air back to the furnace to be warmed and create circulation. In these months, you'll want the lower air return open and the upper air return closed.

Is it better to leave all vents open in winter?

Vents should be open. Closing them can actually put strain on the system and cause damage. It is not more efficient to close vents. The system is pushing out the same amount of air regardless of whether vents in any given room are open or closed, and it's designed to operate efficiently with all vents open.

Which air return vents should be open?

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.

Should vents under a house be open or closed in winter?

Closing crawl space vents in the winter is a good idea, especially if you have plumbing or air ducts in the crawl space. Unfortunately, just closing or covering crawl space vents for the winter isn't the cure-all for cold floors, frozen pipes, and pests.

Misconception: Should I Close Crawl Space Vents in Winter and Open in Summer

At what temperature should I open my crawl space vents?

Those crawl spaces generally have the worst insect and rot damage. If you must close your vents during winter I highly encourage you to do it only when the temperature drops below 32⁰. Otherwise, keep them open when the temperature is consistently above freezing to avoid moisture-related problems.

Should attic vents be open or closed in winter?

Condensation is a major problem in cold weather. In fact, the colder the climate is that you live in, the more you will have to deal with condensation. For this reason, attic vents are essential to homes in cold climates, and they should never be covered in the wintertime.

Can you have too much return air?

Can You Have Too Much Return Air? Too much return air coming through your system isn't much of an issue because the fans and ductwork working to get that air back into the system only pull with so much force to make the HVAC system work correctly.

What room should return air ducts not be installed in?

What room should return air ducts not be installed? Return air ducts should generally not be installed in rooms with high humidity or areas prone to moisture accumulation, such as bathrooms or kitchens.

How do I know which vents are return vents?

You can identify return vents by turning on the system fan and holding your hand or a piece of paper up. If the paper is pulled toward the vent or you feel a suction effect, it's a return vent.

What to do with vents in the winter?

If you have a top/bottom return vent setup, close the top vents in the winter months. 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.

What happens if you close vents in unused rooms?

Closing HVAC vents in unused rooms may damage your HVAC system, leading to costly repairs. Your heating or cooling system produces the same amount of air regardless of how many closed vents you have.

Should I circulate air in house in winter?

Open Windows at Least Once a Day

Proper ventilation can improve winter indoor air quality, and the good news is that it's easy. Opening windows for a few minutes at least once a day will allow stale air to leave your home and fresh air to get inside.

Should you leave vents open in winter?

Keep your home ventilated

Open windows at least once a day, keep window trickle vents open, and air vents uncovered. It's important that air can move through your home as ventilation is one of the best ways to avoid mould, as flowing air means spores can't settle somewhere and absorb water.

What temperature should be coming out of my air vents?

Now, from the example above, with 75 degree air being pulled in at the air filter, what temperature should we expect to be blowing out? Well, the general consensus is somewhere between 14 to 20 degrees colder than the intake temperature. From my example, 55 to 61 degrees would be an acceptable range.

Why are there two air vents in my room?

Having multiple return air vents in the home allows for better air movement and helps to reduce the pressure on the HVAC system.

Should return air vents be open or closed in winter?

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 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 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.

Where is the best place to put return air vents?

Return registers can be large and centrally located in your home, or they can be in every room. HVAC professionals recommend that each room have a cold air return vent to help with flow and temperature control. These vents are typically found on an interior wall.

Does oversizing a return air system cause problems?

Due in large part to the short cycling issues mentioned above, components on an oversized heating and/or air conditioning systems are more likely to fail sooner than those on a properly sized system. As a result, you may end up having to replace your HVAC system sooner than expected.

Does every bedroom need a return vent?

Instead, there should be at least one return vent in every room, with two or three being ideal. If your house has only one return vent, this is not a problem — make sure to keep the doors open in every room so the air can circulate properly. Make sure there are no furniture, draperies, rugs, etc. blocking return vents.

Should you close vents in unused rooms in winter?

“No, you should never close vents in individual rooms,” says Brad Martin, Field Service Manager for Boer Brothers Heating & Cooling in Chapel Hill, North Carolina. HVAC systems are designed to maintain a specific and balanced airflow known as CFM, or cubic feet per minute, throughout a home.

Should I leave my attic door open in winter?

Low temperatures. For your home: Leave the heat on 'constant' to ensure a temperature of at least 5˚C throughout the property (including attic space) Open your attic trap door to help keep the temperature in your attic the same as in the rest of the house and prevent pipes freezing.

Do ridge vents make a house colder in winter?

Some of it should flow up under the roof sheathing to keep it cooler, then exhaust out near the peak of the roof. This airflow out of the roof peak keeps it cooler during summer and much colder during winter to minimize condensation and ice dam formation.

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