Heating, Ventilation, and Air Conditioning (HVAC) systems rely on a critical yet often overlooked component: sheet metal. From ductwork to custom installations, HVAC sheet metal is pivotal in delivering comfortable, clean air to homes and businesses.
The right sheet metal improves durability, energy efficiency, and overall system performance. Our comprehensive guide below explores the importance of HVAC sheet metal, its types, benefits, applications, and fabrication techniques.
HVAC sheet metal refers to the thin, flat pieces of metal used to build and install HVAC systems. These sheets are crafted into ducts, vents, dampers, and other components essential for heat and coolant distribution throughout a residential or commercial building.
Typically made from materials like galvanized steel, aluminum, or stainless steel, HVAC sheet metal is designed to withstand challenging environmental conditions and maintain system efficiency.
Sheet metal is the backbone of an HVAC system. The right metal doesn’t just hold everything together; it also drives efficiency, durability, and performance. High-quality, corrosion-resistant metals extend the system’s lifespan, ensuring smooth airflow and reducing energy consumption. Plus, precision fabrication allows for a perfect fit in any building layout, optimizing heating and cooling efficiency.
An HVAC system has one simple but crucial mission: keeping indoor temperatures just right. That means delivering warmth when it’s cold and cool air when it’s hot. To do this job efficiently and effectively, the system’s components must withstand extreme temperatures, form tight seals, and maintain flexibility while resisting corrosion and breakdown. The strength and quality of the sheet metal make a huge difference.
HVAC ductwork can be made from fiberglass, fiberboard, sheet metal, or coated spring steel wire helix. Of these options, sheet metal is by far the most popular. It’s inexpensive, lightweight, easy to transport, and simple to install. Most importantly, metals can transfer heat and even refrigerant without damaging the ductwork — a property called thermal conductivity.
Opting for sheet metal in HVAC systems offers several advantages:
Aluminum, stainless steel, and galvanized mild steel are among the most common sheet metals for HVACs. The choice of sheet metal depends on specific requirements, such as durability, cost, and environmental conditions.
Aluminum is a popular choice for HVAC coils due to its excellent heat transfer capabilities without the high price tag. Lightweight and resistant to corrosion, aluminum is also often used in coastal or humid environments. Although aluminum can be more expensive than stainless steel on a per-pound basis, its lower density—about one-third the weight of galvanized steel—helps keep overall costs manageable. Its affordability and durability make it a top choice for many HVAC manufacturers — along with steel.
Steel not only conducts heat efficiently, but it also delivers strength and efficiency. Galvanized steel is a popular choice for ductwork because of its corrosion resistance and affordability. For higher-end installations, stainless steel sheet, which is extremely similar to carbon steel except that it contains chromium, is ideal thanks to its superior strength. Galvanized steel is the most cost-effective option among the three metals.
Although sheet metal may be best known as the primary component of ductwork, which transports air to and from HVAC systems, it is also used to make plenums, vents, registers, and custom fabrications.
HVAC ductwork isn’t one-size-fits-all. It must often meet complex and intricate designs, requiring sheet metal that can easily be cut, bent, welded, seamed, and insulated without losing strength and precision. For example, ductwork may need to be oval, rectangular, round, or spiral; sheet metal is also used to make 90-degree elbows, half-sheet rectangular pipes, and X, Y, and Z connector pieces.
Fabrication requires tools like shears, laser cutters, and brake presses. To ensure that sheet metal components meet design and functional requirements, manufacturers use cutting-edge technology such as CNC plasma cutting machines.
CNC plasma cutting machines are essential for shaping sheet metal into precise HVAC duct components. Using a high-temperature, ionized gas jet, these machines accurately and quickly cut through steel, aluminum, and galvanized sheet metal, ensuring minimal material waste.
Once cut, welders assemble the sections using welding techniques like Tungsten Inert Gas (TIG) welding for clean, precise joints or Metal Inert Gas (MIG) welding for efficiency and strength. Seam welding, such as Pittsburgh seams and lock-forming, ensures airtight connections, reducing energy loss. These advanced fabrication methods create durable, leak-proof ducts that enhance HVAC system efficiency and longevity.
Selecting the appropriate sheet metal involves considering factors like material, gauge thickness, and coating options.
Choosing the right material depends on specific needs and priorities. For general HVAC applications, galvanized steel offers durability and cost-effectiveness, while aluminum provides a lightweight, corrosion-resistant alternative. Consider the options in our chart below:
| Material | Common Applications | Benefits | Drawbacks |
| Aluminum | Ductwork, heat exchangers, coil fins, and air handling units | · Lower cost
· High thermal conductivity · Corrosion resistant · Easy to install |
Not as strong or durable as steel; not always efficient in maintaining temperature when conducting refrigerant |
| Galvanized Steel | Various HVAC system components | · Lowest cost option of the three materials
· Strong · Durable · Corrosion-resistant if properly treated · Long-lasting · Cost-effective |
Damage to protective zinc coating can expose the underlying steel to corrosion |
| Stainless Steel | Specialized components | · Suitable for high-humidity environments
· Corrosion-resistant · Long-lasting |
Only used for specialized HVAC components |
Gauge thickness measures the metal’s thickness, which impacts its strength and flexibility. Commonly used gauges for HVAC sheet metal range between 20 and 26, with lower numbers indicating thicker metal. Because HVAC systems must be flexible and easy to fabricate, they typically call for gauges 24 and 26. Higher gauges are also less expensive to manufacture and ship, making them more attractive to buyers.
Protective coatings enhance the metal’s resistance to corrosion, UV rays, and other environmental factors. Popular coatings include:
Zinc-coated, or galvanized steel, is by far the most commonly used coated steel in HVAC applications.
What gauge is sheet metal for HVAC? Depending on duct size and application, HVAC sheet metal typically ranges from 26 to 16 gauge. Residential ducts commonly use higher gauges, while commercial systems require 24 or 22 for durability. High-pressure systems might use thicker gauges, like 14, 16, or 18.
What metal is used in HVAC? Due to their durability and corrosion resistance, HVAC systems primarily use galvanized steel, stainless steel, or aluminum for ductwork.
What is the best sheet metal for ductwork? Galvanized steel is often considered the best for ductwork because of its durability, cost-effectiveness, and resistance to rust. However, aluminum is another good option for lightweight, corrosion-resistant ducts, particularly in coastal or humid environments.
What is the best material for an HVAC system? The answer depends on the component. Galvanized steel is best for ducts, and aluminum for coils. High-humidity areas often use stainless steel due to its rust resistance. Choosing the right material ensures an HVAC system’s efficiency, longevity, and minimal maintenance.
HVAC sheet metal is indispensable to modern climate control systems, offering durability, efficiency, and customization. Whether selecting materials, designing ductwork, or fabricating components, understanding the properties and applications of HVAC sheet metal ensures optimal performance and long material lifespans.
By choosing the right type of sheet metal and using proper fabrication techniques, you can create functional systems that meet a buyer’s aesthetic requirements and ensure comfort and quality for years to come.
Kloeckner Metals is a full-line metals supplier and service center. Kloeckner Metals combines a national footprint with the latest fabrication and processing technologies and most innovative customer service solutions.
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