Air Duct vs. Air Vent: Key Differences Between These HVAC System Parts

You may have heard or even used the words air ducts and air vents used interchangeably, but these two parts of the HVAC system are very different. They work together to supply your home with heated or cooled air from your furnace or AC, but they aren’t the same. That means you must adopt a different approach to cleaning, maintaining, and replacing these parts. Read on to learn the major differences between an air duct and an air vent, from what they look like to how much each costs.

What Is an Air Duct?

Think of an air duct as a passageway for your HVAC system. It distributes heated or cool air throughout your home, regulating indoor temperature and air quality. Ducts also return stale indoor air for filtration and reconditioning. They are typically made of flexible plastic, sheet metal, and even fiberglass.

What Is an Air Vent?

Air vents are openings that allow air to flow in and out of indoor spaces. They help with regular airflow, ensuring air circulation and temperature control throughout your abode.

They come in various types, including supply vents, which deliver conditioned air, and return vents, which pull air back into the system for filtering and reconditioning. Vents often feature grilles or registers to control airflow direction and volume. 

Air Ducts vs. Air Vents: Key Differences

Air ducts and air vents are both essential parts of any HVAC system. These components help distribute warm or cool air from the HVAC unit(s) throughout the home to keep your family comfortable year-round. 

Here is a breakdown of their key differences and functions.

Air Ducts vs. Air Vents: Difference in Purpose

Air ducts are the passages moving air from the furnace or air conditioner through the home. The air vents are covered at each opening where the air ducts connect to rooms. Air vents often have operable slats for opening or closing vents in unused rooms (although, keep in mind this can wear down HVAC parts like the coils and motor.

Air Ducts vs. Air Vents: Difference in Appearance

Air ducts and air vents look entirely different. Air ducts are round or rectangular and long, forming a network of air passages throughout the home. Air vents are flat covers on a wall, ceiling, or floor where the air duct connects to a room.

Size

Air ducts come in many sizes and will extend several linear feet throughout the home. Standard air duct opening sizes range from around three inches by seven inches to 35 inches by 40 inches for rectangular air ducts or about four to 41 inches in diameter for round air ducts. 

Air vents come in standard sizes and will correspond with the size of your air ducts. Air vents are typically available in four-by-10 inches, four-by-12 inches, six-by-10 inches, or six-by-12 inches, although you can also find smaller or larger air vents.

Material

Air ducts come in various materials with varying weights, flexibility, energy efficiency, and durability. Options include non-insulated or insulated flexible air ducts, fiberglass, or sheet metal in galvanized steel, carbon steel, stainless steel, or aluminum.

Vent materials also come in various materials, including plastic, steel, aluminum, cast iron, or brass.

Air Ducts vs. Air Vents: Difference in Life Span

Air ducts will typically last about 10 to 15 years before you need to replace them. That’s because no matter what material they are made from, they are exposed to many pollutants and experience a lot of wear and tear over the years. Old ductwork is prone to leaks and reduced efficiency.

Air vents are just covers over the opening of the air duct, so their life span depends on what material they are made out of, how often you clean them, and how frequently you open or close them. Most air vents with regular cleaning will last 15 or more years. Homeowners may update air vents based on updated style preferences before they stop functioning properly.

Air Ducts vs. Air Vents: Difference in Maintenance

Air ducts and air vents require ongoing maintenance, but there are some critical differences in frequency and ability to DIY.

Air ducts should be inspected by an HVAC professional about once per year. The HVAC professional can check for buildup inside the ducts and any damage or leaks that could make your system work less efficiently. Inspections and air duct cleaning need to be handled by a professional with the proper training and equipment to check inside the ducts.

Air vents are easier for homeowners to maintain themselves. Dusting or vacuuming the surface of your air vents about once per month will help keep them clean. You can inspect air vents for damage, like corrosion or dust buildup.

Air Ducts vs. Air Vents: Difference in Costs

Air ducts and vents come at different costs for installation and ongoing maintenance. If you plan to add new air vents, you must also pay for added air ducts.

New Parts

Air duct replacement costs about $1,400 to $9,000, depending on the type of air ducts, the size of your home, and how much insulation is required.

New air vent covers cost about $30 to $120 each. But if you plan to add a new air vent where one doesn’t already exist, you’ll pay about $200 to $500 for the vent, plus around $1,000 to $9,000 for new air ducts to connect the vent to the rest of the home’s ductwork.

Although you can typically install a new vent cover independently, a professional must install new ductwork. Many municipalities prohibit DIY ductwork installation, which could cause you to fail home inspections. Even if it’s legal in your city, improper installation could damage the air ducts or leave gaps, causing air leaks that will significantly increase your energy bills. Instead, hire a professional duct installer near you to ensure this job is done correctly.

Cleaning and Maintenance

Air duct cleaning costs $150 to $800, and this job has to be done by a professional air duct cleaner. This should be done about every three to five years. You can also schedule annual HVAC inspections; HVAC inspections cost about $70 to $500 each.

Cleaning air vents costs about $25 and $50 per vent, but this is one job that handy homeowners can tackle on their own. You can use a vacuum with a hose attachment or a microfiber cloth to clean the exterior of the air vent. A couple of times a year, you can take down removable vent covers and wash them with soap and warm water, then dry them before replacing them.