We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Construction

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Are the Different Methods for Duct Construction?

By Tracy Powell
Updated: May 17, 2024
Views: 9,311
Share

In most cases, the methods for duct construction are dependent on the type of duct being installed and the constraints of the physical space. The overarching process is usually about the same for all ducts; the biggest differences usually center on the materials used and the specifics of the building’s layout. In general, there are three main types of duct systems: low-pressure, medium-pressure, and high-pressure. Identifying the duct system at issue will help determine the type of work needed for the job and will also frame the methods needed for optimal construction. Different tools and components may be required for different projects, too. Components such as diffusers, registers, flues, vents, roof penetrations and filters may or may not be required, and knowing when and how to use these and other similar pieces is a big part of construction in most cases.

Understanding the Different Types of Duct Systems

Ducts are basically large passageways built into the walls or ceilings of various structures in order to funnel and direct airflow. They’re normally connected to heating, ventilation, and air conditioning (HVAC) systems. Homes and offices built with central air almost always have ducts planned from the drafting of the structural blueprint; in a sense these are the easiest to install since they’re built with the structure and can be integrated seamlessly. It’s common for older structures to be retrofitted with ventilation systems later, though duct construction in these cases may have to be more carefully planned to fit within a structure that may not easily be able to accommodate all systems.

Most duct systems, whether new or existing, fall into one of three categories based on how much pressure they’re designed to withstand or support. All look similar in terms of their physical qualities, but things like how much support they’ll need on the inside and how much clearance they’ll need within the walls or ceilings often takes some careful calculation. The precise method a construction engineer will need to use also depends a lot on the contours of the structure, its size, and features like whether air needs to circulate between floors. Variables including the number of vent openings and their size also factor in in most cases.

Maximizing Efficiency

All duct construction involves components that maximize ventilation efficiency. Major elements include corner closures, elbows, hangers, “T” connections, fire dampers, access doors, and air intakes. Duct fittings include caps, offsets, single-branch take-off, square-to-round transitions, register box, and round flexible duct reinforced with spiral wound wire. The galvanized sheet metal used should have a galvanized coating on both sides of the sheet equal to at least 1.25 ounces (35.4 g) of zinc per square foot (0.09 square meters) and should generally be of lock-forming quality.

Focus on Vibration

The best duct design is one that utilizes these construction components to eliminate vibration, which is accomplished by tightly installing rigid, constructed metal ducts. Rectangular ducts should be made with standing seams and braced with angle iron to stiffen the sheet and avoid vibration. The velocity in the main duct and the remote branches should be lowered gradually to distribute the air uniformly. This is done by increasing the size of the duct, and it usually cuts down the friction in the smaller ducts.

Problems with Pressure Loss

Reducing “leakage” is another important aspect in duct construction. Air pressure loss within the duct system can be avoided by soldering, welding or otherwise sealing all joints and seams to make them tight. They also can be riveted or spot welded. The lap joints should be made so that the outlet of one length of ductwork fits into the inlet end of the next length of ductwork in the direction of airflow.

Share
About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
Share
https://www.aboutmechanics.com/what-are-the-different-methods-for-duct-construction.htm
Copy this link
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.