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How to Open and Close Round Ceiling Vents

If you find yourself circling underneath your round ceiling vent, trying to figure out how to open or close the darn thing, then comfort yourself with the knowledge that you are not the first, nor will you be the last. I have spent far too much time doing this myself.

When done right, opening or slightly closing ceiling vents can help you to regulate your house temperature and provide comfort and conditioned air in every season. As you will see below, how you adjust the vents depends on what type of vent it is. Additionally, as half the problem can be determining if the vent is open or closed, we’ll look at this as well.

Round vents with adjustable grills are opened or closed by twisting the vent’s middle disc. Round vents with rigid grills have an adjustable damper behind the grill (special tool required). Some vents have grills that turn to open and close a damper. For all, turn clockwise to open and anticlockwise to close.

Three Types of Round Vents

If you have a round ceiling vent, there are two different possible ways of opening and adjusting it. Depending on the exact type of vent, you will either be able to adjust the vent grill or the damper of the vent.

1. Vent With Adjustable Grill

Round ceiling vents often come in sleek designs with adjustable grills (the slatted portion of the vent) that allow you to open and close the vent as much or as little as you desire. What is even better is that you don’t need any additional tools to do that, only the grill itself.

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Climbing on a step stool, take hold of the center portion of the grill and turn it.

For a visual demonstration, you can go to the one-minute mark in the following video.

Turning the adjustable grill counterclockwise will close the vent; rotating the grill in the clockwise direction will open it.

Just be careful not to overdo it with the latter motion so that the grill does not get completely unscrewed from the vent!

2. Rigid Grill With Adjustable Damper

The second type of round ceiling vent is the one that has a rigid grill (so you will not be able to twist it), but behind the grill is hidden an adjustable damper.

You can usually tell that your vent does not have an adjustable grill if you see those cross-bars between the grill. A gentle twist can also confirm that you have a vent with fixed grill.

The dampers come with a specific tool that allows you to open the damper if you turn it clockwise and close the vent if you turn the tool anticlockwise.

So, the whole adjusting process depends on one small tool that can easily get misplaced. Is there any household item that can replace it?

Nothing is stopping you from going through your cutlery drawer to see whether you find something that could match the lost tool and be used in its place. You could also try using a screwdriver.

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However, the arguably more reliable option is buying a tool adjustment set and looking for the perfect match there.

From what I saw online, many of the original tools that come with the damper seem to be single D tools, which is also part of this adjustment tool kit (amazon link).

But naturally, you need to check what tool fits your damper best, always remain careful, and refrain from using hard force to avoid damaging anything.

Here is a great video for you if you want to see how the adjustable damper works and how to install it properly.

3. Combines Mechanism

There is a third type of round ceiling vent that seems to combine the two designs. In other words, you adjust a damper behind the grill but you do so using the grill itself, not a tool.

You can see what I mean in the following video.

As with the previous mechanism, a clockwise turn will close the damper and an anticlockwise turn will open it.

Unlike the first type of vent, you cannot over twist the grill to the point at which it screws right off.

Can Round Vents Be Adjusted?

Being able to only fully close or fully open a ceiling vent is not optimal since the vent should never be fully closed, which we will further discuss in a second.

Ideally, you want to be able to adjust the vents according to your current needs and personal temperature preferences that will be affected by the changes in seasons and weather.

All of the adjusting options mentioned above allow you to not only open and close the vent but also let you choose anything in between, thus adjusting the vent accordingly.

Partially closing the second and third type of round vents might create a directional shift in airflow as you are not reducing the space between the grills. You are, instead, closing off sections of the vent.

You Should Not Close Your Vents

It may seem like a rational decision to close your ceiling vent in unused rooms or in a basement. After all, this way must be more energy-efficient and save you money in the process, right?

Not quite!

The functioning of an HVAC system is often misunderstood, leading to similar myths and mistakes people make, such as closing the vents in an attempt to save energy and redirect hot or cold air to certain parts of the house.

In reality, closing the supply vent in order to achieve better efficiency or temperature regulation will likely have the exact opposite effect.

By doing so, you will increase pressure in the HVAC system, making it work harder, consuming more energy, increasing the chance of leaks or motor failure, potentially decreasing the air quality in your house, and ultimately costing you more money.

As you can see, it is better to leave the vent open, and if the need arises, you can adjust it so that the flow of air is reduced but not completely eliminated.

How to Tell if Vent Is Open or Closed

There are two different types of HVAC vents—supply and return vents. Your round ceiling vent will typically serve as the supply vent, meaning it distributes conditioned air into the room.

This means that if the HVAC system is on, you should feel the air coming out of the vent if you hold your hand in front of it or alternatively see hold a piece of paper and note if it is moving or not.

You can also try turning the grill or adjusting the damper in the clockwise direction and then fully close it by turning counterclockwise to see if you notice any change in airflow during this.

Air duct on ceiling in the mall or hospital
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It is possible that you will hear a weak whistling noise if the vent is closed, but there is some air leaking through it.

And, of course, often you will be able to judge whether the vent is open or not by simply inspecting it with your eyes, even though not all grill designs will allow you to see it clearly.

However, if you checked the vent and you are positive that it is open, but there is no airflow, it is time to inspect your ducting.

There may be some leaks, damage, or disconnection in the ducting that is causing the lack of airflow. You may also have installed dampers inside your ducting that got closed and are now restricting the air.

Learn the difference between a vent, grill, register, and diffuser.


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