Supply Air Diffuser FAQ Guide
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  • Jimmy at
  • November 07, 2022

1. What is a supply air diffuser?


A supply air diffuser is a diffuser in a ventilation system whose function is to allow air to flow into a room from the outside.

This is done by letting the air flow out of the ventilation system into the room.


supply air diffuser


2. What is the supply air diffuser used for?


The function of a supply air diffuser is to achieve proper room ventilation by sending air into the room from the outside.

This happens whenever air enters the air supply diffuser and then exits the HVAC.



3. What is the difference between a supply air diffuser and a return air diffuser?


The function of the supply air diffuser is to allow air to flow into the room from the outside.


Return air diffusers allow air to flow from the building to the outside.


Supply air diffusers allow air to flow out of the ventilation system, while return air diffusers allow air to flow into the ventilation system.


The size of the return air diffuser is usually larger than that of the supply air diffuser.


In HVAC, the number of supply air ventilation is usually greater than the number of return air diffusers.


The supply air diffuser is connected to the supply air duct, and the return air diffuser is connected to the return air duct.



4. Where can supply air diffusers be installed?


You can install a supply air diffuser in any of the following locations


● floor
● door top

● within the piping system



5. How do supply air diffusers compare to linear diffusers?

Linear air diffusers allow air to flow directly into the room.


Supply air diffusers allow airflow into the room at a given angle.


Linear air diffusers are usually semi-recessed, while supply air diffusers are not concealed in any way.


The function of linear and supply air diffusers is to ventilate a room by allowing air to flow.



6. What is the shortest distance from the return air diffuser to the supply air diffuser?


The design of your HVAC system will determine the distance between the supply air diffuser and the return air diffuser.



As a general rule, neither the return air diffuser nor the supply air diffuser system should be too close together.



7. What is the acceptable CFM airflow for the supply air diffuser?


Acceptable CFM airflow from a supply air diffuser depends on the range and noise of the supply air diffuser.



However, the range of CFM is between 2.0 and 3.5 m/s. Other factors that determine CFM include the type of supply air diffuser you use.



8. How to determine the size of the supply air diffuser?


● it depends:
● ventilation area
● Width and length dimensions of ventilation areas
● ceiling height
● space aesthetics
● CFM per foot.

● Installation location


A general formula for sizing a supply air diffuser is to divide the CFM by the airflow in the room.



9. What is the difference between a diffuser and an air grill?


An air diffuser is a device that uses profiled blades to supply air at different angles in a room.



Air grilles allow air to flow vertically into the room without any deflection.



Types of air diffusers include louvered vanes, straight vanes, and linear slots.



Types of air grills include egg grates and conveyors.



A damper is usually installed on an air grill without an air diffuser.



10. Does the supply air diffuser have a maximum wind speed?


Factors that determine maximum air speed:



The noise level of the air diffuser


Design and Type of Supply Air Diffusers and Throws


In most cases, the speed can be in the range of 2.0 to 3.5m/s.



11. How do I specify a supply air diffuser?


The specification of which supply air diffuser to choose depends on the following factors:

● Airflow in CFM
● Noise Standards for Supply Air Diffusers
● Pressure drops.
● throw

● terminal speed



12. What are the throws associated with HVAC diffusers?


The throw is a measure of air circulation in a room from an HVAC diffuser.



It is usually measured in the direction of airflow from the HVAC unit.



The unit of measurement is feet.



13. How to avoid sweating on the air diffuser?


You can avoid sweating on your air diffuser by doing any of the following:

● Properly isolate pipes
● Properly seal all crawl spaces
● Install a dehumidifier when outdoor humidity is high
● Periodically clean filters or clean air handling ducts.
● Seal any leaking pipes inside the air diffuser.