
In Part 1 of this story, we covered many of the quality features that go into Marlo commercial and industrial heating coils and cooling coils, including our heavier tube wall thicknesses, superior fin construction, extruded tube sheets, welded box headers, and tube sheets fortified with copper ferules.
These features, along with the ones discussed below, simply are not offered by many other coil manufacturers – especially those offering “discount” prices. At Marlo, our goal is not to offer the lowest cost coils. Our goal is to provide the best value – combining quality, performance, durability, longevity and price. Here are several more of the many ways we’re able to do that.
Hairpins
Marlo coils under 12 feet long have U-shaped tubes inserted into the coil, rather than using all straight tubes joined by brazed return bends. This reduces the number of brazed joints by up to 50%, drastically speeding production. In addition, the bending process work hardens the copper, resulting in a more durable coil with longer expected life. Our precision, automated hairpin bending machine creates the 180˚ bends in seconds, using tube lengths of up to 24 feet for a 12-foot-long coil.
Superior casing construction
While many coil manufacturers use 18-gauge steel (.048” thick) for their casings, Marlo uses 16-gauge steel (.060” thick) casings at a minimum. That’s a 25% or more improvement in steel thickness compared to many of our competitors, resulting in increased durability and longer coil life.
In addition, Marlo has the ability to bend up to 159” long top and bottom channels in one piece, which makes for a stronger and more cost-effective coil. Other manufacturers need to rivet their top and bottom channels together (called splicing) to make a coil longer than 96”. In the rare cases when we need to splice coils, all splices are welded to ensure the strongest top and bottom channels with zero air leakage through the spliced joints.
Another difference in Marlo casings is that they are bolted together, as opposed to using pop rivets like many coil manufacturers. Also, standard Marlo construction includes a double break on the top and bottom channels, which further improves strength, ensuring the coil holds its shape and does not distort under load.
Headers and connection stubs
Marlo uses only thick wall copper tubes for our headers, which provides a large surface area for brazing to assure the highest strength possible. Holes for connections are precisely drilled to ensure accurate hole location of the connection stubs, the smallest braze joints possible, and the highest strength joints.
Our connection stubs are typically copper with black iron pipe connections, allowing for the most precise thread and robust pipe joints. This is far superior to the copper threaded stubs used by some of our competitors, which distort and are easily damaged, creating leaks and making installation difficult.
Leak testing
As a final quality check, every Marlo heating or cooling coil must pass an underwater leak test before it leaves our facility. Each finished coil is pressurized to a much higher level than the intended use of the coil, and then completely submerged under water in one of our large test tanks.
During the test, pressure gages are monitored for any drop in pressure, while experienced Marlo employees watch carefully for any sign of air bubbles coming from the coil, which would signify a leak. Only after the required time passes with no signs of a leak being observed is the test ended. This assures the coil is leak-free and ready for shipment.
Three-year warranty
Another area where Marlo leads the coil industry is with our warranty, which includes three full years, compared to just one year with most other coil manufacturers. How can we offer a warranty that is three times longer than our competitors? The answer is simple: all of the quality construction examples listed above, and in Part 1 of this story.
With so many high-quality features built into every coil – especially those that add strength and durability – it should be no surprise that Marlo coils naturally last longer than those that aren’t built to the same standards. We know how well we build our coils, and that makes it easy for us to offer a warranty that other manufacturers can’t.
When you consider all the “extras” you get with Marlo commercial and industrial coils, we think it’s clear that you get more for your money. Whether it’s a chilled water coil, hot water coil, steam coil, refrigerant coil, dampered face and bypass coil, process heating coil, process cooling coil, or any of our wide range of specialty coils, you’ll always get a coil you can rely on. Plus, every Marlo coil is custom built to meet the needs of your specific application.
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