Most HVAC steam heating coils operate with steam pressure below 25 PSIG, and a very large percentage are below 15 PSIG. These coils have specific piping and coil arrangement requirements to allow these systems to optimize performance and avoid systematic problems that require premature replacement. Preheat coils in most of the country will require an arrangement that deals with below freezing air temperatures. In conjunction with...
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Coils are an unusual piece of equipment and often very misunderstood by most of the HVAC Industry. At USA Coil & Air, we take quality control seriously from the time we receive an inquiry until the manufactured coil has been installed. USA Coil & Air is primarily in the replacement and fast-ship business. For us, Rule #1 is the “clock is running” when the problem or...
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Many heating and cooling coils are installed in air handling units with very limited access to the unit. This often occurs because the original designer didn’t give much thought to possible future replacement of the coils and fans. We have all seen ductwork, electric lines, water lines, boilers, chillers, pumps, and other air handlers where it’s impossible to install a new coil. The pull length...
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It’s often difficult to understand circuitry on a chilled water coil. Changes to the “circuitry” and changes to the “tube diameter” will affect the overall capacity and pressure drops. Each time you change the circuitry on a coil selection, you have a positive, which relates to a higher capacity or lower fluid side pressure drop. The negative is either a lower capacity or a higher...
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Operating water coils that are prone to air temperatures below freezing normally need the use of anti-freeze. The most common is glycol. This has been used for over 40 years, and there are two common types, ethylene and propylene. Anti-freeze provides a safeguard if there are mechanical or electrical breakdowns that may cause fluid to sit in a coil with below freezing air going across...
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The Mercedes Benz Superdome in New Orleans is world renowned. It’s the largest fixed domed structure in the world and has been the home of the New Orleans Saints and the Sugar Bowl for many years, as well as being a recipient of The NFL’s premier game; The Super Bowl. This incredible structure opened in 1975 and had been known for years as simply “the...
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Finned tube coils are meant to have contact with the air flow, as more contact creates more heat transfer. Heat transfer is nothing more than heat exchanged from one medium to another, and the goal is to create maximum heat transfer efficiency. The downside to this process is the coil’s susceptibility to foreign materials becoming lodged in them. The following explores this problem in a...
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Many projects require downstream duct mounted coils to heat or cool air to its final desired temperature. Normally there are upstream coils that regulate the leaving air temperature to a design intermediate level. The duct coil takes the air from that intermediate level to its final desired temperature. Many systems can vary the air flow or water volume to achieve a desired leaving air temperature...
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HVAC and process heating/cooling must deal with the added tonnage created by using fresh air from outside. Most times, the requirement for fresh air is mandatory and can go from 10% all the way to 100 % of the system air flow. There are numerous rules and regulations written to eliminate air flow quality problems, including bacteria and other micro-organisms, that can cause health problems....
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Florida is known for its beautiful beaches, great weather, pristine communities, and senior traffic heading to the “Early Bird Specials”. For many, it’s considered to be paradise! The state has continued to grow every year since 1950, and its continued growth seems assured. During the winter months in the northern and central portions of the state, old man winter still comes knocking from time to time...
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