Energy Efficient

Ductwork leakage is often, and correctly, cited as the single largest source of energy in the built environment. Based on a survey of predominately rectangular duct systems, the annual cost of this energy waste runs into the billions of dollars. Engineers, code officials and owners are taking notice and questioning the use of ducted HVAC systems. There is a simple ducted solution, factory fabricated spiral duct and fittings. It has long been recognized that spiral duct systems leak a great deal less than comparable rectangular systems. This can be easily explained when looking at the source of leaks, seams and connections. First let’s consider the seam. Rectangular duct seams, such as a Pittsburgh Seam, require sealing, either during production or in the field. Spiral seams on the other hand require no sealing and this is recognized by ASHRAE Standard 90.1. Our AMCA testing proves out the ASHRAE standard regarding spiral seams. The testing shows leakage rates so low as to be inconsequential.

The second source of leakage is the field connection. Rectangular duct is provided in nominal 5’ long pieces plus fittings as required to change size or direction. Spiral duct is provided in lengths up to 12’ long. Because of this length difference, and taking into consideration the number of fittings required, 30% or more of the field connections can be eliminated. Careful use of factory mounted branches on spiral duct can allow the elimination of almost 50% of field connections. In other words the use of spiral can eliminate the opportunity for leakage by almost half. Overall even SMACNA, whose members make large quantities of rectangular duct, admits that rectangular duct can be expected to leak at least twice as much as spiral round and flat oval duct. If the Pittsburgh seams aren’t sealed, you can expect rectangular duct to leak four times as much.

Easy to Install

Round and oval spiral duct systems are easier to install than traditional rectangular systems. Why, the duct on average weighs less and is easier to handle but most importantly, there are fewer connections. Spiral is readily available in cut-to-length pieces up to 12' long. Making 30% or more fewer connections is an easy way to achieve significant field labor savings.

Easy to Seal

Round and flat oval spiral duct systems have four great sealing advantages. The first and most obvious is the spiral seam. It is the only duct seam short of a full weld that does not require sealing according to ASHRAE 90.1. The second advantage is that the perimeter of round and flat oval duct is less than rectangular so each joint that must be sealed is smaller. Third, there are fewer of these smaller joints. Finally there is the joint itself. Most rectangular duct leaks are at corners which are difficult to seal. On average you can easily expect to use one third of the sealer, and one third of the time to seal your round and flat oval sytems versus rectangular duct systems. Of course you can also install Eastern Tight or Eastern Flange systems and reduce the need to seal even more.

Looks Great

Spiral duct has an aesthetically pleasing helical seam that can be seen in both large volumes spaces like retail outlets and transportation hubs, as well as more intimate settings such as lofts and restaurants. Exposed duct can be left unpainted or can easily be painted on the jobsite to match the color scheme of your choice.


Range of Products

Eastern Sheet Metal can fill all of your spiral duct and fitting requirements. In both our Cincinnati and our Dothan location we manufacture single wall round, dual wall round, single-wall flat oval and dual wall flat oval spiral duct and fittings as well as offering you the option to have the round and flat oval experts at ESM fabricate your long seam welded round and flat oval exhaust systems.

Range of Materials

ESM is a true custom manufacturer of spiral duct systems. This means you can get your ductwork in G90 galvanized steel, “paint grip” steel, 304 and 316 stainless, 3003 aluminum, poly coated steel and anti-microbial coated steel. ESM also offers a full range of insulations for dual wall spiral. You can have our standard unfaced fiberglass insulation, mat faced fiberglass duct liner, or our E-Free insulation with a polyester rayon facing to prevent fiberglass from entering the airstream. ESM also offers a full range of elastomeric products.

Range of Sizes

ESM offers the widest size selection of round and flat oval spiral duct and fittings available. Our round spiral sizes include 3” to 30” diameters in one inch increments and 32” to 84” diameters in 2” increments. We offer 379 flat oval sizes with minor axes from 4” to 36” deep.

Labor and Energy Savers

The Eastern Advantage

ESM is the industry leader in providing you with labor saving options that are also energy savers. Our patented Eastern Tight system, provides a Class 3 sealed system, the most stringent requirement, without additional sealing in the field. For larger round, and flat oval 10” and larger, we offer the Eastern Flange, A T25A shaped, factory mounted, screw through flange that only requires a peel and stick gasket to complete a Class 3 seal. The Eastern Advantage - Save labor time with the Eastern Flange and Eastern Tight and deliver a duct system free of leakage points.

AMCA Certification

ESM is one of a select few spiral manufacturers that offer AMCA certified spiral duct. ASHRAE 90.1 clearly states that spiral seams do not have to be sealed, and we have the certification to prove it. In the coming months we will be going through the AMCA certification process for our Eastern Tight and Eastern Flange connections as well as our flat oval spiral duct. We also have our own dual wall data for liner erosion, and sound attenuation.

Customer Service

We realize you have choices when buying spiral duct and fittings. We can offer you superior products and great prices, but you need your spiral duct to easy to install and to arrive at your job-site on time. That is why almost every ESM job ships on a dedicated truck, and with easy to be follow piece marked installation drawings.

Buy America

ESM uses only domestically produced steel and satisfies the provisions of Buy America and the American Reinvestment and Recovery Act. Please contact your local rep, using our Rep Locator, to find out more.

Your Local Representative

We think we have the best reps in the HVAC industry. With their wide range of complimentary airside lines and with years of industry experience, your local rep will give you the personal service that you will not get from a direct sale factory or a website. To contact a local rep, please use the Rep Locator.


High-Performance Air Systems

High performance air systems (HPAS), when correctly designed and installed, are still the gold standard for energy efficient HVAC system, outperforming "new" technologies such as chilled beam and variable refrigerant flow systems. An HPAS can incorporate many elements including the latest in VAV technology, sophisticated controls, static regain design methods, low temperature supply air,and air side economizers to maximize free cooling. But, all HPAS require the use of spiral duct and fittings to provide the system with the least resistance, and the best leakage performance.

Standard HVAC

Spiral is ideal for high performance systems, but not all systems are high performance. Still the advantage of spiral systems, low-leakage, light weight, easy to seal and install are the attributes that any owner or engineer is looking for in a conventional HVAC installation.

Sound Control Applications

Break-out noise and system noise are just two of the issues that can plague the acoustical environment of all buildings. Controlling these noises can be critical especially in applications such as schools or performance venues. Eastern dual-wall round and dual-wall flat oval spiral duct and fittings provide an effective way to control both kinds of noise. Round, with no flat surfaces, and flat oval with less flat surface than rectangle, are naturally resistant to breakout noise whether dual-wall or single wall. The use of dual-wall duct, that is, duct where the inner wall of the spiral duct is perforated providing a path for the sound to be asborbed by the sound deadening insulation, is a cost effective way of dealing with sound propagatian and transmission noise.


We think spiral duct looks great, but sometimes people just don't want to see it. For those rare occasions, maybe a church sanctuary or a theater, Eastern has a solution, poly coated underground duct work. Our Eastern PCS for underground is a robust and corrosion resistant spiral duct which is ideal for your underground application.

Fume Exhaust

The superior air handling characteristics of round are well known, and round duct has been the duct of choice for the fume extraction industry. In the case of fumes, where abrasion is not an issue, the lighter rigid walls of machine made spiral duct can result in significant savings over hand fabricated round duct. Spiral duct for fume removal is readily available in 304 and 316 stainless steels as well as polycoated products, which in some instances can outperform stainless, such as Eastern PCS.

Dust Removal

Like fume extraction duct, dust removal duct is usually round. In dust removal applications where abrasion is not a major issue, Class 1 and Class 2, the use of spiral duct in lieu of hand-made duct can result in significant savings.

Architectural Applications

Spiral duct is the preferred duct for exposed duct systems. It has an aesthetically pleasing helical seam that can be seen in both large volumes spaces like retail outlets and transportation hubs, as well as more intimate settings such as lofts and restaurants where spiral can lend a industrial chic to the space. Exposed duct can be left unpainted or can easily be painted on the jobsite to match the color scheme of your choice.


How Do I Specify Spiral Duct?

Designing and specifying round and flat oval spiral duct is simple. To help you on your way you can use Eastern's suggested specifications and design considerations. These are written to work hand in hand, so your specifications are clear, concise and without extraneous information often found in pre-purchased spec packages.

Does Spiral Satisfy Leed?

The LEED process has become a necessary and integral part of the already difficult to navigate construction environment. As with any relatively new, and changing, set of standards there are myriad opportunities for misinterpretation, misinformation and mistaken applications of the standards. ESM fully complies with LEED. Click here for the ESM LEED compliance submittal. For additional information, click here for the ESM presentation, “LEED 2009 and Duct Systems – Demystifying Prerequisites and Credits”. This power point presentation will address some of the issues being encountered by fabricators of HVAC duct, both rectangular and spiral. LEED Prerequisites and potential Credits for duct will be examined with particular attention paid to Materials and Resources plus Indoor Environmental Quality. The session is intended for contractors, engineers and commissioning agents.

Can I Paint Spiral Duct?

Painted spiral duct is very popular in gymnasiums, restaurants and other exposed applications. ESM provides both standard galvanized steel and "paint grip" steel, For more information on what kinds of steel are available, and how to paint them, click here.