What Is an Air Diffuser?

It's common knowledge that hot air rises and cool air settles, but when it comes to your interior air, this can be a frustrating fact. After all, you want the air in your home to be evenly distributed.

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This is where an air diffuser comes in. These compact contraptions help spread out the airflow from your heater or air conditioner so you get total comfort from corner to corner.

What Does an HVAC Air Diffuser Do?

An air diffuser for HVAC systems replaces or goes over your standard room vent to better direct the airflow. This helps even out room temperatures and can even reduce noise. While a standard grill over an air vent is designed to keep things out of the ductwork, a diffuser purposely controls the actual flow of air.

A standard vent grille often only sends air directly downward or has limited adjustability. This can make certain parts of the room hotter or colder than average. Instead of clustering with your family and pets in that one perfect spot, spread the pleasant temperatures around with a diffuser.

Sometimes, the flow of air from your heater or air conditioner can get loud, especially when your HVAC system is working hard to bring the temperature up or down. Because a diffuser spreads the flow of air, it can make your system quieter and your home more peaceful.

How and Where Are HVAC Air Diffusers Installed?

Some HVAC air diffusers snap over the existing vent, while others replace the vent entirely. They can be installed directly onto the ductwork and sealed to prevent loss of cooled or heated air. Most diffusers are installed on ceiling vents, but models designed for wall or floor vents are also available.

With a multidirectional diffuser, you can adjust the levers to point air toward a specific area that tends to be colder or hotter than you want. Another option is to set up the diffuser to aim air back toward the ceiling, which increases overall airflow and forces warm air down in winter instead of letting it pool above everyone's heads.

How Much Does It Cost to Install an Air Diffuser?

Adding air diffusers to your vents is part of air balancing, the process of adjusting your HVAC system to ensure consistent temperatures throughout different rooms. According to The Family Handyman, the cost of air balancing is around $75 to $100 (CAD 107 to CAD 142) per opening, so the total cost depends on how many vents and rooms you have.

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Choosing an Air Diffuser

When you're considering an air diffuser for a room, think about the natural airflow patterns and your decor. You can find diffusers that match most standard ceiling colors. Models include round, square and rectangular versions, and you can find diffusers made of steel, resin or aluminum.

Most diffusers are ceiling models, which are installed directly into a drop ceiling. Slot diffusers are long, narrow devices made to fit into a slot in a wall or ceiling. Adjustable diffusers have levers that let you switch the direction of airflow in different seasons.

Round diffusers spread air out in a 360-degree pattern, so you get an even distribution of heated or cooled air to every side of the room. The air heads outward along the ceiling and down the walls to spread everything out instead of concentrating it on a specific spot. Square diffusers with a step-down design work similarly to round diffusers. These types need to be installed in the center of the room.

Multidirectional square diffusers have different sections that can be aimed in specific directions, giving you better control over exactly where the air is going. You can aim all the vents toward one spot or move the fins to point air at different locations in the room.

In most cases, HVAC diffusers operate without any special care. Basic diffuser maintenance includes cleaning the surface occasionally to reduce dust buildup and inspecting the fins for any cracks or signs of bending. If your diffuser has adjustable levers, move those every once in a while to prevent sticking.