Air ducts and air vents are two essential parts of HVAC systems. They maintain the airflow throughout the home, regulate indoor temperatures, and balance the air quality. However, “air ducts” and “air vents” are used interchangeably despite their different purposes. Homeowners and building managers must know the differences and their specific use cases to increase energy efficiency, comfort, and system performance and to understand how the ducts and vents work together.
If you are wondering what is the difference between air ducts and air vents yourself; you’ve come to the right place.
What Are Air Ducts?
Air ducts are an essential part of the HVAC system. They are long tubes or pipes that transport conditioned air (heated or cooled) from the central AC unit to different rooms. They maintain consistency in air temperatures and quality in the house and commercial spaces.
Their function is to transport air throughout the house. The hot air comes from the furnace, and the cool air comes from the air conditioner. Ducts are used as a pathway to deliver comfort to every room.
The materials used are specific to the air ducts.
- Sheet Metal Air Duct: Sheet metal ducts are used to ensure durability.
- Fiberglass Air Duct: Fiberglass duct boards provide insulation and noise reduction.
However, they are not as durable as metal ones.
- Flex Air Duct: Flexing ducts combine plastic and metal. They are not as durable as sheet metal ducts, but they offer flexibility and adaptability.
There are two main types of air ducts — rigid and flexible.
- Rigid ones are made of metal sheets, aluminum, or galvanized steel. They are durable, puncture-resistant, and less prone to leaks. The smooth interior is helpful for larger buildings and long-term insulation. However, they are not flexible enough to adjust in tight spaces.
- Flexible ducts are made of plastic or metal wire. They are easy to bend and fit into tight spaces. They are used in residential areas and short distances. However, they are more likely to get damaged, and airflow efficiency will decrease if they are not installed properly. Flexible ducts are used in homes for their easy installation and low cost.
Air ducts serve as the highway for your HVAC system. They connect the central unit to the rooms in your home. The system works by forcing air from inside of the house through return vents and circulating through the air ducts. Then, the HVAC unit conditions the air by heating or cooling it before sending it back through the supply ducts, which are then distributed evenly in all the rooms.
What Are Air Vents?
Air vents are the openings we see or cover in walls, floors, or ceilings. It allows air to flow into or out of the room. They are like the entry and exit points of the ventilation system. Air vents are where conditioned air enters the rooms and from where the stale air is pulled back for reconditioning.
The types of air vents are:
- Supply Vent: Supply vents deliver conditioned air into the room. These vents are connected to the air ducts. Locating supply vents is crucial to ensure that the air reaches through these points and goes to every corner of the rooms.
- Return Vent: Return vents work oppositely from supply vents. They pull stale and unconditioned air from the room back to the HVAC system.
- Grills & Registers: Grilles and Registers are two different covers. Grilles are stationary vents that flow air freely. They don’t have any adjustment options. They are used in return vents where controlling airflow is less essential. But registers are used for their adjustable slats. It controls the direction and amount of airflow. Registers are used with supply vents, allowing the homeowners to adjust temperatures in each room.
Basically, air vents distribute conditioned air to the living space. When air enters the duct, it runs through the supply or return vents.
Understanding The Differences: Air Ducts vs. Air Vents
| Air Ducts | Air Vents | |
| Physical | Long, tube-like structures. Made from metal, fiberglass, or flexible materials | Openings covered by grills or registers |
| Location | Kept hidden behind walls, ceilings, and floors | Visible by all and placed strategically on walls, ceilings, and floors to allow airflow. |
| Function | Transporting air | Directing and regulating air |
| Materials | Usually, made of sheet metals, plastic, and fiberglass | Usually made of metal or plastic |
| Common issues | Leaks, poor insulation, loss in efficiency due to improper installation of the ducts | Restricted airflow due to blocked or dirty vents from debris and dust accumulation |
Frequently Asked Questions — FAQs
- Can we use air vents without air ducts?
No. They both are part of the ventilation system. Ducts are passageways, and vents control the entry and exit of the air. Air cannot travel from the air conditioning system to the vents without ducts.
- How do you tell if you have a problem with air ducts or vents?
There are several indications we will face.
- Uneven temperature and discomfort
- Excessive dust, stale air, and musty odors
- Energy bills spike due to leaks or damages
Understanding the difference between air ducts and air vents makes a lot of work easier for homeowners. Regular inspection and cleaning of these ducts and vents are key to ensuring the best performance. The National Air Duct Cleaners Association (NADCA) revealed that the efficiency of the AC unit improves once contaminants are removed and leaks are sealed on the ventilation systems. This reduces cost and improves air quality. Even the people living in the house are affected less by allergies and respiratory issues.