SPR 2018

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Page 16 of 38

B Y J E R R Y M Y R E N Applying improper cleaning solutions and techniques for air conditioning con- denser and evaporator coils can not only damage the coils, but it can also cause long-term premature refrigerant leaks and heat transfer reductions. Unknowing service techs may be slowly destroying most of the coils they are supposedly degreasing, cleaning and brightening. The wrong coil cleaner on fins can show visible destruction, but the hidden danger is the electrolytic breakdown of the all-important heat- transferring bond between copper tube and fin that typically remains unseen. For example, several service techs misdiagnosed a homeowner's complaint of high electric bills and insufficient cooling as a slightly corroded and dirty outdoor coil. They thoroughly cleaned it; however, the problem persisted until a thorough exam found little heat transfer from tubing to fins. The bonds had apparently disintegrated from another service company's improper rinsing after applying chemical coil cleaners. The only solution was coil replacement. In a commercial example, a national restaurant chain's disintegrated coil fins on several prematurely failing rooftop units was a puzzling mystery worthy of a Stephen King or John Grisham novel. Obviously, the unit failures were closely associated with the damaged coil inefficiencies, but the mysterious fin corrosion was an intriguing challenge for HVAC wholesaler Insco Distributing Inc. The 57-year-old distributor with 35 locations throughout Texas spearheaded solving the mystery. Insco didn't want to risk losing the long- standing customer loyalty of the chain, which operates hundreds of locations nationwide under several brands. The mystery wasn't solved over- night, but Insco's John McGaughey, regional manager, and Shawn Craig, NATE, distributor service coordinator and chemical supplier, RectorSeal LLC, investigated the damaged units, discov- ered several possible causes and created a solution. WAS IT THE RTU MANUFACTURER? The restaurant chain, which operates its own in-house service department with more than 50 technicians in the Houston area alone, first suspected one of Insco's top RTU brands was providing equipment with substandard coils. The RTUs, which range between from 15 to 20 tons, had developed overheated compressors and complete burnouts. Furthermore, efficiency was spiraling downward as much as 50-75 percent after just a few years of operation, according to the affected locations' utility bills. In other cases, many units just stopped working altogether from overheating, according to the chain's service manager complaints. To make matters worse, it wasn't every one of the dozens of units Insco had sold to the customer over the years, but rather random units at certain locations across the Greater Houston area. Craig, a former 10-year service tech with 28 years of experience in the industry, inspected several affected sites and found more of a horror story than a mystery, because some of the units' coil fins actually crumbled when touched. "This really caught us off guard," said Craig, "because there are literally thousands of these same-model units throughout Houston, and hundreds of thousands across the country. We hadn't seen this severity of fin damage except with this restaurant chain." Insco invited the manufacturer's regional service manager to inspect. The service manager claimed it was something within that particular chain, because other restaurant chains hadn't experienced any type of fin damage to similar models and sizes. WAS IT THE CHEMICAL CLEANING AGENT MANUFACTURER? Prior to the fin damage, a sales rep from the chemical manufacturer the chain now uses more sparingly invited the chain's technicians to its warehouse for training. Unfortunately, the training was more of a sales pitch than the hands-on training needed to properly clean coils. Also, the chemical the manufacturer touted as "neutral" leaned more toward alkaline than a balanced pH chemical. Furthermore, Craig noticed one service tech buying an extremely caustic chemical for an application that didn't warrant it. "When I saw that, I knew some of the chain's service techs weren't following their training guidelines," said Craig. The link between HVAC health, proper coil cleaning solutions and techniques MAINTAINING EFFICIENCY Coil cleaning chemicals are invaluable when used properly. Service contractors should periodically review their crews' cleaning methods. COIL CLEANING GUIDELINES 1. Shut off unit before cleaning. 2. Always wear protective eyewear, gloves, work boots and any other precautionary safety wear. 3. Without protective gloves, do not come in contact with coil cleaner. 4. Do not inhale the vapors of the coil cleaner. 5. When mixing, always add the concentrated coil cleaner to the water in the sprayer. 6. Do not use sprayers with aluminum parts. 7. Always read coil cleaner directions, and follow dilution ratios. 8. Avoid back spray from wind. 9. Liberally apply coil cleaning solution to coil surface. 10. Let solution work for 5 minutes before rinsing. 11. Rinse coil and surrounding area thoroughly with low-pressure water. 12. For cooking grease applications, allow a non-acid coil cleaning solution to work eight minutes before rinsing. Repeat if necessary. HVACPproducts.com HVAC & Plumbing Product News \ Spring 2018 14

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