The Best of Extra Edition: June 20, 2016
At www.achrnews.com, The NEWS’ Extra Edition page is home to hundreds of online-exclusive service and maintenance, technical, and business management articles. Here are some of the best.
QUICK FACTS: EVACUATION
Evacuating a refrigeration system serves two primary objectives: It removes noncondensables, and it dehydrates (removes water vapor). If noncondensables such as air are not removed, the system will operate at higher than condensing pressures. This happens because the air is trapped at the top of the condenser, effectively reducing the condenser capacity. Increasing the condensing pressure results in higher compression ratios and higher discharge temperatures, both of which decrease system efficiency and can lead to decreased reliability.
BTU BUDDY 28: A STOPPED UP CONDENSATE LINE
The dispatcher called and told Bob that a customer had a real problem with a condensate leak. The unit in the attic had leaked so much that it overflowed into the insulation in the attic, which became heavy and caused the sheetrock in the ceiling to fall through into the upstairs den. Bob arrived within 30 minutes and the customer was really mad, as Bob’s company had installed the unit about two years ago. Bob calmed the customer down by listening to him and then said, “There must be some explanation to this. I will get to the bottom of it and give you a full report.”
HOW TO INCREASE EFFICIENCY, REDUCE MAINTENANCE, AND IMPROVE IAQ WITH UV
Mold spores are encountered everywhere in homes and workplaces. The majority of molds are not a source of irritation because we encounter them in small concentrations. However, when mold spores find the right environment — damp and dark conditions — they will multiply to the point of affecting HVAC performance and possibly occupant health. Fortunately, there is a low-cost, easy-to-maintain, energy-efficient solution for eliminating mold growth in HVAC systems — ultraviolet (UV) germicidal lamps.
BTU BUDDY 27: A COMPRESSOR WITH AN INTERNAL LEAK
Bob got a call from the dispatcher that a drug store was having trouble with its cooling system. The system had been working well until yesterday, when it began to get warm in the store. It was a 7.5-ton unit with a reciprocating compressor using R-22. Bob initially thought this was a classic case of low charge, but then he was unsure. Btu Buddy asked, “What seems to be the problem?” Bob said, “I don’t know. This compressor’s running really hot, but everything else seems normal. There seems to be enough refrigerant returning to cool it, but it is not cooling it.”
Publication date: 6/20/2016