The Aluminum Side Of The Great Coil Debate

March 8, 2002
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Pictured is American Standard's four-sided coil. With its radius corners, the company says this eliminates return bends and provides maximum efficiencies. (Photo courtesy of American Standard and Trane.)
When The News asked for additional comments at the end of the article “Aluminum Vs. Copper: The Great Condensing Coil Debate” (Feb. 18, The News), the floodgates opened. Out rushed Trane and American Standard dealer-contractors.

In this article, we present their counterpoint to Bob Forty’s (president, Energy Services Air Conditioning and Heating Co., Naperville, IL) pro-copper opinions. Trane and American Standard also wanted to take the opportunity to explain their aluminum coil design to the hvacr industry.

On this aluminum side of the debate are contractors Jim Welzig, owner of Welzig Heating & Air (Longmont, CO); Keith Reynaud, owner of A&H Service Co. (Kenner, LA); Mark Gibson, owner of Gibson’s Heating and Plumbing (Waterloo, IN); and Lee Robinson, owner of Climate Design (St. Petersburg, FL).

Each of these contractors respected Forty’s right to his opinion; each also wanted to make sure that the other side of the condensing coil debate is told.

The major points from the aluminum camp include:

  • Condensing coils made with copper tubes and aluminum fins are not automatically superior. A lot depends on design and construction and the specific alloys employed.
  • Copper may be strong, but it is not necessarily stronger than aluminum. Again, the way the coils are constructed is more important than the metal used.
  • Aluminum coils can be more reliable than copper coils — and these contractors said they can prove it.
  • There’s no questioning the ease of maintenance of aluminum coils, especially the Spine Fin.
  • There’s no questioning the heat transfer characteristics of aluminum coils, especially the Spine Fin™.

    Spine Fin's unique configuration requires no end turns. Brazed connections occur only at coil inlet and outlet, reducing potential leaks, says Trane and American Standard. (Photo courtesy of American Standard and Trane.)

    THE DIFFERENCE IS THE DESIGN

    If you have not guessed by now, the difference of opinion regarding aluminum coils centers around Spine Fin and its construction. Only Trane and American Standard offer this design, which they say sets it apart from the rest of the aluminum coil competition.

    “In all the years I have been selling Trane, I’ve had only one leak ever on any Spine Fin coils,” said Welzig. “We never have leaks.”

    Gibson said he puts in 200 to 250 American Standard units a year, “and we have had only two coils replaced.”

    Reynaud has known about the Spine Fin for a long time. He started out as a General Electric dealer in 1973. GE originally introduced this coil technology. When GE sold its hvac business to Trane, he became a Trane dealer. He is now an American Standard dealer.

    “I’ve been a big Spine Fin proponent,” he said. “We don’t have any problems with the coils. The aluminum tubing on this coil is twice as thick as any copper coil that is made. It is rifled on the inside. This is aluminum to aluminum, so you don’t have any dissimilar metals.”

    “When you use the same material for the fins, it eliminates dissimilar metals problems,” agreed Robinson. “Actually, it reduces the opportunity for leaks. Trane, in its particular units, has a four-side, completely enclosed cabinet that is unique in the industry, thus protecting the coil even more from the potential of foreign objects being thrust into it or thrown by a lawnmower into the coil and potentially causing leaks.”

    Robinson also said the aluminum coils are superior in his coastal area of St. Petersburg, FL. “The effects of salty air on copper coils is not good. I can’t say that about Spine Fin — and we have dealt with a number of different manufacturers over the years.”

    Robinson noted that manufacturers other than Trane often place restrictions on usage and the application of their equipment in coastal environments. “Normally they will make some disclaimer that they don’t want their equipment installed within a half mile, two miles, etc.,” he said. “They each have a different standard.

    “Trane has no restrictions on the use of their units and their coils in the coastal environment and they warranty their equipment. That speaks of their experience with their coil and the overall quality of that coil’s construction.”

    Without leaks, repairing Spine Fin coils is virtually unheard of. Should a coil leak, however, the manufacturer usually replaces it, said Robinson — “which is rather easy to replace due to the construction of the unit and the way they do it,” he said.

    FEWER JOINTS, FEWER LEAKS

    Folks from Trane and American Standard’s Residential Systems Group (Tyler, TX) discussed the finer points of their coil’s design.

    “Where coils are apt to leak is at joints; one of the points that leads to the use of Spine Fin is the fact it has far, far fewer joints than does a plate fin coil,” explained Jim Crawford, former director of Technology, now director of Regulatory Affairs for Trane. “That doesn’t make plate fin [coils] good or bad. That’s just the intrinsic difference.”

    The manufacturer explained that its coil is manufactured on patented, high-speed machines that cut, form, and wrap aluminum ribbons around aluminum tubing. The tubing rises through a blue adhesive bath in the center of the machine; the bath coats the tube. Tension rollers wrap the fin ribbons tightly to the tube with the bonding adhesive to ensure good heat transfer. The extruded adhesive forms a barrier against capillary attraction, which might draw moisture into the crevice between the base of the fin and the tube. By sealing moisture and electrolytes out of the tube/fin space, galvanic and crevice corrosion is minimized, the company said.

    Spine Fin coils are fabricated in continuous lengths. Brazed connections are required only at the coil (or circuit) inlet and outlet. This configuration helps eliminate end turns and reduces potential leaks, the company said.

    According to the manufacturer, a typical 2.5-ton air conditioner or heat pump equipped with a plate fin coil requires approximately 30 brazed joint connections; a modern Trane or American Standard unit of the same size requires about 10.

    “The issue was raised about the copper-to-aluminum connection in the coil,” said Crawford, “and that brings you back to how good of a joint do you make? Do you know what you’re doing? How many joints do you make? With Spine Fin coils, we make fewer joints. Therefore, there is less of a propensity to have a problem from that standpoint. The people who are doing this have a great deal of experience.”

    CLEANING AND REPAIR

    With low leakage, repairs are seldom needed on a Spine Fin construction. However, if a repair is required, brazing is possible.

    “We have a coupling kit that can be put on that joint very effectively,” said Loran Dailey, team leader of After Sale Support. “If we have a problem in the aluminum area, we’ve been using a product produced by Allstate Welding that is very effective at brazing or repairing small holes in aluminum. But we just really don’t have a problem with these coils.”

    Said Crawford, “I think we need to stress the fact that many people have had bad experiences in other applications and other industries trying to braze aluminum. But it comes down to this: You have to have the right materials, and you have to know what you’re doing. That’s true of any brazing.”

    As for cleaning, “Whenever we’re faced with cleaning one of these coils, it’s a very simple matter to simply take a water hose and wash the coil off from the inside out,” explained Dailey. “If we look at the Spine Fin and how it’s been constructed around the tube, those air-entering surfaces have the greatest opportunity to capture dirt and lint by circulating the air.

    “Whenever we wash the coil from the inside out, we’re washing that collected contamination right off the outside surface. So cleaning the coils has not been an issue at all. They’re very easily cleaned.”

    Additional comments on the aluminum-copper debate will be accepted, but will be published on the “Feedback” page. Please send them to Feedback, The News, 755 W. Big Beaver Rd., Troy, MI 48084; 248-362-0317 (fax); LetterstoTheNews@bnp.com (e-mail).

    Publication date: 03/11/2002

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