Where Should Return And Supply Vents Be Located?

Are you thinking about installing a new air conditioner in anticipation of the summer season? Maybe the old air is too old or inefficient. So, you feel a new unit can improve indoor air conditions while reducing your energy bills. Or perhaps it’s a new home that requires a new AC.

Whichever the case, you must understand the importance of correct vent placement. Although there’s some room for manoeuvring on the actual location, putting your HVAC supply and return vents in the wrong places can result in poor cooling, AC inefficiency, and an increased risk of AC damage, among other issues.

This guide explains how to pick the perfect placement spots for your supply and return vents for maximum AC performance.  

What’s the Correct Placement for AC Return and Supply Vents?

Generally, return air vents perform best on interior walls – not the walls adjacent to the outdoors. Meanwhile, supply vents perform best on exterior walls, ideally under a window.

More importantly, ensure the return vents aren’t too close to the supply registers. The air conditioning supply register is above and just a few feet from the central air conditioning return grille.

The cool air delivered from the supply register will mostly fall down and be drawn back into the interior wall.

Understanding your HVAC System

The first step to correctly install your air conditioner vents is understanding the difference between supply and return air ducts and their roles in the entire duct system. Otherwise, you may mix up the two.

What are Air Supply Vents?

Supply ducts or registers are airways through which conditioned air from your air conditioner flows into your home. In other words, they’re the vents through which the air conditioner “supplies” your home with conditioned air.

They are typically installed on exterior walls, though floor and ceiling installations are also common. The most important objective is to distribute the conditioned air evenly throughout the home.

As such, you may find/need supply registers in every room, though a few AC systems can work with one centrally located supply duct.

What are Air Return Vents?

Air conditioner air return vents are the pathways that carry the air back to the furnace or air handler where it will circulate back out through the heating and cooling system.

In other words, they’re the vents through which stale indoor air “returns” to the air conditioner for cleaning and cooling.

Return air vents are typically installed on interior walls to prevent interference from the outdoor environment. However, ceiling and floor configurations are also common. Central air systems almost always have several return vents for maximum air circulation.

Supply and Return Air Duct Placement 

Choosing the right location for your AC supply and return vent placement is critical for proper AC functioning and optimal indoor comfort. Here’s why you should seek the perfect placement and the dangers of poor vent location.

Importance of Correct Aircon Vent Placement  

Placing the air conditioner vents (both return vents and supply vents) in the correct locations is critical for several reasons;

1. It promotes maximum airflow

Proper airflow is paramount to efficient air conditioning. It’s at the center of the cooling process. Hot, stale air enters the AC via return vents, gets cooled, and comes out at the supply end as cooled air – and the cycle continues.

However, proper airflow depends on the location of the vents. For instance, if you position the return vents poorly, air will struggle to enter the AC, compromising the cooling process.

2. It promotes cooling efficiency 

We’ve already seen how putting the return vents in the wrong location impacts airflow into the AC. The good news is that air conditioners always try as much as they can to pull more air to compensate for the poor positioning.

However, this too comes at a cost – increased energy bills. An AC working harder and longer to pull more air consumes more electricity than necessary.

3. It promotes AC health

One of the dangers of poor airflow inside the air conditioner is freezing. You see, air conditioners rely on very cold refrigerants to extract heat from indoor air.

The heat extraction happens as hot air from the return registers flows across the refrigerant-filled evaporator coils.

The refrigerant absorbs the heat, evaporates to a gas, and flows back to the compressor for compression back to liquid.

Now, imagine that there’s not enough hot return air due to poor return vent location! The cold refrigerant lines would eventually freeze and potentially burst, necessitating expensive replacement.

4. Ensures maximum indoor comfort 

Finally, correct positioning of the vents is critical to optimal indoor comfort.

For instance, if the supply vents are put in the wrong locations, the conditioned air may struggle to reach every corner of the room, leading to hot spots throughout your home.

Similarly, poorly located supply vents can bombard guests with blasts of cold air, causing serious discomfort.

Dangers of Incorrect Placement 

To summarize, poorly located supply and return vents can lead to the following air conditioning problems;

  • Poor airflow throughout the home
  • Hot spots throughout your rooms
  • Accelerated air conditioner wear
  • Increased risk of condenser and evaporator coils
  • Pressure imbalance in your air ducts
  • Higher energy/electricity bills
  • AC short cycling
  • Increased risk of vent damage/blockage

How to Position Supply and Return Ducts Correctly 

With the above factors in mind, you should move every obstacle to ensure that your aircon supply and return vents are installed in the correct location.

The following is a quick guide to help you pick the perfect spot for each vent.

Height Considerations 

Return vents are flexible when it comes to height. The most important thing to remember is that return registers exist to return air to the air conditioner.

Therefore, you need to position them at a height where they’re best placed to draw maximum stale indoor air with few obstructions. So, ceiling and wall vents make the most sense.

Supply vents are a little different because the location of the ductwork is critical. So, many AC systems have supply vents on the floor if the ducts are located in the crawlspace or the ceiling if the ductwork is located in the attic.


Proper AC register placement promotes even cooling throughout the house. You don’t want hot spots in corners or other difficult-to-reach places. You also don’t want some rooms cooler than others.

But this doesn’t mean you need a return vent in every room. Some systems are designed to work this way but most modern duct systems have one or two systems for the entire HVAC system.

For this reason, we recommend placing a supply register in every large room. You can also connect and loop several supply registers in a web to terminate at key points throughout the room.

The registers must not be too close to the door. Otherwise, you may lose the conditioned air. The same applies to return air vents.

Window Placement 

We recommend installing air supply vents right under the window opening to cool any outdoor air entering your home. It may seem counterproductive, but it’s very practical.

The warm air will be cooled and then becomes heavier and sinks to the floor region so that it’s not lost through the window.

However, avoid locations close to the window opening when installing return vents. Instead, return vents should be located close to where people sit in the home, with as few distractions as possible, to maximize airflow into vents.

Distance between Supply and Return Vents 

Finally, you should keep the supply and return vents far enough from each other. Otherwise, the cool supply air would slip back into the return vents for re-cooling even before it cools the room.

Returning still-cool air to the AC is bad for several reasons. For instance, it would leave your home as hot and sweaty as before because the cool air doesn’t circulate throughout the room.

This can cause the AC to run non-stop as it works harder to reach the heat setting, assuming the thermostat is located across the room. Even worse, there’s a risk of the air conditioner freezing.

What’s the Best Location for AC Vents?

Best Place for Supply Air Vents

The best location for the supply vent is on the wall, right under the window opening. However, ceiling installation and floor installations also work a treat as long as your heating system has sufficient BTUh capacity and fan. The location of the air ducts may limit your choice.

Best Place for Return Air Vents

The best AC air return duct locations are on the floor but free from obstructions, such as furniture and carpets.

Otherwise, place them on the ceiling. Fortunately, you don’t have to worry about the location of your HVAC ducts when choosing an air return vent location.

Why Ceiling Vents are Common 

Although you can install an air conditioner supply and return vents pretty much anywhere as we’ve seen, you may have noted that most people prefer to have both on the ceiling. It’s not rocket science. Ceiling installations are more practical for four reasons;

  • Proximity to ductwork: Most homes have HVAC systems in the attic, especially those without a crawlspace. This can force you to install supply vents in the ceiling. Or would you rather install new ducts running from the attic down the walls or to the floor?
  • Fewer obstructions: Unlike walls and floors, ceilings have fewer obstructions. You rarely need to worry about furniture, wall art, or family photos standing in the way.
  • Cost-effective: Which is easier between boring holes in a wooden ceiling and drilling holes into a concrete wall/floor? Yes, it matters.
  • Thermodynamics: The law of convection states that hot, lighter air rises to the ceiling while cold, heavier air settles around the floor. Thus, the ceiling makes great sense for return vents.
  • Floor-plan friendly: Finally, space is often at a premium on the floor and walls. So, you may have to move several items to prevent vent obstruction. You don’t have to worry about the same when selecting installation spots on the ceiling.

Floor Vents are Cool, But

You can install supply and return vents on the floor, and many people do. However, floor installations present several challenges;

  • Ductwork accessibility: Unless your home has HVAC ducts in the crawlspace (most homes don’t), floor installations mean you need to find clever ways to access the ductwork in your attic.   
  • Furniture issues: This is a major issue, especially in tiny rooms. How do you ensure maximum airflow and eliminate obstructions with all the furniture?
  • Dirt: You have a duty to keep dirt, including pebbles and other solid particles, from entering and blocking the vents. This is a major problem when the vents are on the floor, right where the dirt particles are concentrated.
  • Kids and pets: Finally, keeping HVAC vents in open areas, free from obstruction, and simultaneously keeping the kids and pets away from the vents can be an arduous task.

Other Poor Location Choices for Aircon Vents

  • Basements: Unless you regularly use the basement, installing aircon vents in the basement invites trouble, given the poor basement conditions. Basements also tend to harbor mold and are typically very moist. If you must, find a separate AC system for the basement.
  • Exterior walls: Supply vents typically go on the exterior wall. However, return vents must never be on exterior walls.

Supply and Return Vent Placement FAQs 

Where do you put return air vents? 

The ideal location for return air vents is interior walls, close to the floor and free from obstructions. However, ceiling installations are more practical to avoid obstructions.

How close can a supply be to the return vent? 

Ideally, return vents and supply vents should be on the opposite ends of the room. However, if both are on the floor or ceiling, make sure they are on opposite ends.

Does every room need a return vent? 

Ideally, yes. You want to have return vents in every room in your home. In fact, you should spread out multiple vents in large rooms for maximum air circulation.

Should return vents be up or down? 

If you strictly follow the law of convection, which states that hot air rises while cold air falls, air conditioner air return vents should be up.

Should return vents be on the floor? 

Ideally, no. Placing return vents on the floor exposes the vents to dirt and debris, which can quickly block the AC filters. So, you should consider having them on the wall or ceiling.

Should a thermostat be placed near return air? 

Yes, it’s best practice to place the thermostat near the air return vent as return vents hold room temperature air. You can place them anywhere else but not close to air supply vents.


Industry best practices recommend installing supply vents on an exterior wall, right under the window. Meanwhile, return air vents can go on the opposite wall, at least a few feet off the floor.

However, you can install both vents on the floor or ceiling if conditions permit, as long as you ensure sufficient clearance. Give us a call if you have any questions.