4 Common Types of Air Ducts - And Why They Matter

Are There Different Kinds of Air Duct Systems?

Every central air conditioning or heating system has one thing in common - air ducts. And while the ductwork in any HVAC system serves the same basic function - connecting the AC or furnace to all of the rooms in the building - not all air ducts are alike. Air ducts come in various shapes, sizes, and materials to suit different needs and applications.

But if the wrong ducts are installed, it can impact everything from energy efficiency to indoor air quality. In addition to the material and type of ducts used, the overall design of the air duct system plays a vital role in system performance. So this article will lay out everything homeowners need to know about the different types of air ducts, the pros and cons, and why it's so important to install the correct type.

Why Different Air Duct Designs Are Necessary

Naturally, since residential homes and commercial buildings vary so widely in size and design, there's no one-size-fits-all air duct layout. In some cases, the air ducts branch out like a spiderweb from an AC or heater in the center of the building. In other cases, one large duct runs from one end of the house to the other, with smaller ducts branching off it to each room. These are two of the most common duct designs, but myriad variations exist.

Several factors influence the design and construction of an air duct system. The house layout will dictate the design of the duct network, but another crucial aspect to consider is the BTUs of the HVAC unit. The BTU (British thermal unit) rating essentially denotes the system's heating or cooling capacity. A unit that's too powerful or too weak for the home's ductwork and square footage will result in poor performance and airflow issues.

HVAC professionals consider all of this when installing new ductwork or a new air conditioner or furnace. Just as important, however, is the type and material of the air ducts themselves.

Common Air Duct Types

Different air duct materials have their advantages and disadvantages. The most common and familiar type are sheet metal air ducts. These are made from either aluminum or galvanized steel. They are durable and relatively easy to install, and their smooth surfaces make them resistant to mold and bacteria growth.

Fiberglass-lined air ducts have fiberglass coating on the interior or exterior of the duct, which helps insulate the ducts, prevents condensation, and muffles the sound of the unit. This type of duct is more common in commercial buildings. Two key drawbacks of fiberglass-lined ducts are that fiberglass particles can break away and enter the air and that the porous surface is more likely to harbor mold and bacteria - both of which can bring down indoor air quality.

Fiberboard air ducts are similar to fiberglass-lined ducts, but they are sealed to ensure no fiberglass particles can break away. However, they are also more likely to harbor mold growth, and their rough interior surfaces can produce friction that may hinder airflow.

Flexible air ducts are typically made of a steel wire coil wrapped in durable yet malleable plastic. This type of duct is ideal for tight or awkward spaces where the above types of ducts are difficult to install. However, their accordion-like structure and flexibility can result in poor airflow, collapses, or kinks.

Which Type of Air Duct Is Best?

The best type of air duct will mainly depend on the specific building and one's priorities. Fiberboard and fiberglass ductwork is typically more prevalent in commercial buildings, where sound muffling is more important due to the huge, noisy commercial HVAC systems.

Most residential properties use sheet metal ductwork, with a few sections of flexible ductwork in narrow spaces and tight corners. Sheet metal ducts are also generally recommended for their air quality advantages (low mold risk, no nasty fiberglass particles). Due to their smooth surfaces, these also require less frequent (and easier) air duct cleaning. However, since so many complex factors go into selecting ductwork, it's always best to consult with a trusted HVAC expert to determine the best type of air ducts for the home's specific needs.

About Chris Wilson Plumbing & Heating Repairs Inc

As a family-owned and operated local business, Chris Wilson Plumbing & Heating Repairs Inc has provided award-winning service to Monterey since 1999. They offer competitive pricing, rewarding membership plans, and 24/7 emergency service. Chris Wilson personally guarantees satisfaction on every job, so homeowners know they're in good hands when they call for AC service in Monterey, CA!