HVAC Tag

Hot Water Coil

The HVAC industry has many manufacturers of units that all have heating and/or cooling coils as an integral part of their package. There are also many free-standing coils in large built up systems and some are mounted in duct runs from a central station unit. What they all have in common is the presumption that all the coils will meet the designated performance. They do...

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Condenser

  Almost all packaged A/C or split system units do not have a service factor for extra capacity. Even when new, these units may not yield the cooling BTUH capacity specified due to improper installation and/or incorrect load calculations at the inception of installation and startup. Consequently, as the system gets older and parts become less efficient, the system may lower its capacity to the point...

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Fan Coil Units

Air handling units that include single and double wall air handlers have had energy saving devices available for many decades. First, there was the variable inlet vane which reduced air flow and power consumption during off peak conditions. The latest way is to place a Variable Frequency Drive (VFD) in the unit, which is more efficient than its predecessor, the variable inlet vane. VFD installations...

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Booster Coil

There are many existing systems that require the addition of cooling to a heating-only unit. Systems need to keep pace with changing requirements for spaces that include a mandatory requirement for cooling. Existing systems can already have cooling, but a booster will have to be placed into the system to add additional cooling.   When cooling is added, it must be decided whether the tonnage can be...

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Fan Coil Unit

Many existing fan coil unit installations have inherent performance issues that relate to the original design and/or systemic conditions that decrease overall performance. Fan coil units are direct drive – the motor is directly connected to a squirrel cage fan. This arrangement clearly defines the volume of air based on external static pressure and the amount of dehumidifying at the chilled water coil. There’s very...

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Industrial Coil

The generic terms “industrial “and “heavy duty” are used to describe an HVAC coil that has an arrangement and/or construction that creates quality heat transfer when adverse temperature, pressure, or a corrosive agent are present. Standard HVAC coils are constructed of copper tubes, aluminum or copper fins, and galvanized steel. The normal temperature for these materials is 250 degrees F and 200 PSIG pressure.   Enter Carbon...

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Maintaining Your Air Handlers

  Central station air handlers require constant attention to ensure the units perform efficiently and have a longevity of up to 2 to 3 decades. By their very nature and because of space conditions, these units almost never have enough space and access to make this job an easy one.   Most units fabricated before 1985 are a single-wall type with insulation exposed to the air flow and...

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Sectional Coil

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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