The website Dictionary.com describes “manifold” as “something having many different parts or features.”

When the word is applied to the world of ductwork fabrication, it has a more specific meaning: preassembled duct with fittings already installed, meaning it’s ready to install as soon as it’s pulled off the truck. This eliminates the time and expense related to fabricating on-site.

It’s a trend that Mike Bailey, the vice president of sales and new product development at Mestek Machinery, said he has been noticing for the last five years or so.

“There’s a change in this industry when it comes to pre-construction in the shop versus in the field,” Bailey said. “It’s been gaining momentum.”

For general contractors, manifolded ductwork offers several advantages for their projects, he said, including quality control.

A lot to like

“The general contractors like (it) — the trucks are delivering two to three sections ductwork with the taps already installed,” Bailey explained. “They feel like they’re getting a better product and its less man-hours in the field. Another major benefit of manifolding in the shop environment is applying duct sealants to all transverse joints, longitudinal seams and taps and access doors.”

This will help when it comes to stringent leakage tests in the field, he added.

It represents a major HVAC construction change in how duct is handled prior to installation. Traditionally, the taps and other accessories are added at jobsites, necessitating that the duct be cut by hand, following patterns and markings that are often also hand-drawn.

It’s a potential problem as well as a site of possible bottlenecks, Bailey said.

“This process can take a long time to do, and it’s (potentially a source of) human error,” Bailey said. 

In a sheet metal shop with a fully automated coil line, such as Mestek’s Profabriduct, which features inline plasma cutting, ductwork can be fabricated with access doors and taps already marked as the duct comes off the machine, saving considerable time — and money. “See a hole, put a tap in it; see a square, put an access door in it. Less input with greater output and less chance of human error.

“They’re cutting their taps, their access doors, into the ductwork … and they’re putting these taps or access doors or takeoffs into the ductwork in the shop, controlling the labor,” Bailey said.

Labor saving

As Bailey has pointed out before, labor is one of the few areas where sheet metal contractors can save money via productivity including software and hardware — meaning machinery. Manifolding duct also saves time.

“All you’ve got to do is hang it. It’s a win for everybody,” he said.

Under its Iowa Precision line, Mestek has released a promotional brochure on the benefits of manifolding ductwork using the company’s products, including the Cornermatic Combo, TDC-V, Cornermatic Plus and the Vulcan 1600WJ waterjet cutting. The brochure outlines the process from design using CAD-CAM software, which downloads drawings to the machine, to fabrication, assembly and delivery.

Some contractors may not immediately realize the major efficiency benefits, Bailey said.

“We have a true X-Y inline plasma cutter in the coil line,” he pointed out. “Without having that, when you have to cut holes in the ductwork via an access door — a round tap, a collar — you have to take a tape measure and measure and then mark the takeoffs for later cut outs via hand held shears.”

But giving up that control, for some longtime sheet metal contractors, can be hard to accept, Bailey acknowledged.  Not all contractors are convinced of the time and labor savings, since it does require setup in the shop. But with a tight job market, tight schedules and labor costs continuing to rise, the savings are real, he added.

 “In today’s market place finding knowledgeable, young talented people who actually want to learn a trade and work hard can be a challenge in this industry,” he said.

Download: IPI Manifold brochure PDF

Under its Iowa Precision line, Mestek Machinery has released a promotional brochure on the benefits of manifolding ductwork using the company’s products, including the Cornermatic Combo, TDC-V, Cornermatic Plus and the Vulcan 1600WJ waterjet cutting. The brochure outlines the process from design using CAD-CAM software, which downloads drawings to the machine, to fabrication, assembly and delivery.