A notable trend in the HVAC and refrigeration world is that contractors are increasingly repairing defective aluminum heat exchangers and return elbows rather than ordering new parts. This change is due to two factors: a disruption in the supply chain and a reduction in manufacturer warranties.
        While supply chain issues seem to have abated, the long wait for new parts to arrive is years and difficult to keep in stock. Obviously, when equipment fails (especially refrigeration equipment), we don’t have time to wait weeks or months for new parts.
        While new parts are becoming more readily available, repairs remain in demand. This is because many manufacturers have reduced their warranties on aluminum coils as they have found that a 10-year warranty is not possible for aluminum, which is a thin metal that can be easily damaged. Basically, manufacturers underestimate the amount of spare parts they send out when they offer long-term warranties.
        Copper was the backbone of HVAC systems and refrigeration coils until copper prices rose in 2011. Over the next few years, manufacturers began testing alternatives and the industry settled on aluminum as a viable and cheaper option, although copper is still used in some large commercial applications.
        Soldering is a process commonly used by technicians to fix leaks in aluminum coils (see sidebar). Most contractors are trained to braze copper pipe, but brazing aluminum is a different matter and contractors need to understand the differences.
        Although aluminum is much cheaper than copper, it also presents some problems. For example, it’s easy for a refrigerant coil to get dented or gouged when doing repairs, which understandably makes contractors nervous.
        Aluminum also has a lower soldering heat range, melting at a much lower temperature than brass or copper. Field technicians must monitor the temperature of the flame to avoid melting or, worse, irreparable damage to components.
       Another difficulty: unlike copper, which changes color when heated, aluminum has no physical signs.
        With all these challenges, aluminum brazing education and training is critical. Most experienced technicians have not learned how to braze aluminum because it was not necessary in the past. It is very important for contractors to find organizations that offer such training. Some manufacturers offer free NATE certification training – my team and I run soldering courses for technicians who install and repair equipment, for example – and many manufacturers now regularly request soldering information and instructions to repair leaking aluminum coils. Vocational and technical schools may also provide training, but fees may apply.
        All that is needed to repair aluminum coils is a soldering torch along with the appropriate alloy and brushes. Currently available are portable soldering kits designed for aluminum repair, which can include mini-tubes and flux-cored alloy brushes, as well as a storage bag that attaches to a belt loop.
        Many soldering irons use oxy-acetylene torches, which have very hot flames, so the technician must have good heat control, including keeping the flame further away from the metal than from the copper. The main purpose is to melt alloys, not base metals.
        More and more technicians are switching to lightweight flashlights that use MAP-pro gas. Composed of 99.5% propylene and 0.5% propane, it is a good option for low temperatures. The one-pound cylinder is easy to carry around the jobsite, which is especially important for demanding applications such as rooftop installations that require climbing stairs. The MAP-pro cylinder is usually mounted with a 12″ torch for easy maneuvering around equipment being repaired.
        This method is also a budget option. The torch is $50 or less, the aluminum tube is about $17 (compared to $100 or more for a 15% copper alloy), and a can of MAP-pro gas from a wholesaler is about $10. However, this gas is extremely flammable and care is strongly advised when handling it.
        With the right tools and training, a technician can save valuable time by finding damaged coils in the field and performing repairs in one visit. In addition, renovations are an opportunity for contractors to make extra money, so they want to make sure their employees are doing a good job.
        Aluminum is not a favorite metal for HVACR technicians when it comes to soldering because it is thinner, more ductile than copper, and easy to pierce. The melting point is much lower than that of copper, which makes the soldering process more difficult. Many experienced solderers may not have aluminum experience, but as manufacturers increasingly replace copper parts with aluminum, aluminum experience becomes even more important.
       The following is a brief overview of soldering steps and methods for repairing holes or notches in aluminum components:
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       Upon request In this webinar, we will receive an update on the natural refrigerant R-290 and its impact on the HVAC industry.
       This webinar will help air conditioning professionals bridge the gap between two types of refrigeration equipment, air conditioning and commercial equipment.