One of the Most Damaging Mistakes in HVAC System Design - Ignoring Part Load

One of the most common mistakes in HVAC system design is the lack of understanding of how equipment reacts at part load. Most equipment is sized for full-load temperature control with minimal attention to part-load temperature and humidity control.

In this episode, we use psychrometrics to explain what happens at part load and the features you want to use to ensure proper temperature and humidity control over all load conditions.

This third installment of our series builds on the information in parts 1 and 2. The links to all three sections are provided below.

Watch Psychrometrics Part 1: https://youtu.be/vd2mPSVqvZ4

Watch Psychrometrics Part 2: https://youtu.be/4Z_usQB9vQ8

Watch Psychrometrics Part 3: https://youtu.be/hhsAsyX3VBc

Download your Psychrometric Chart Here: https://www.insightusa.com/psychrometric-chart-pdf

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We cover the full-load and part-load psychrometric processes of constant volume air handling units, including features like face and bypass and return air bypass. The dehumidification process is explained with varying reheat sources of electric heat, gas heat, and hot gas reheat.

By the end of this episode, you'll have a comprehensive understanding of psychrometrics and be able to apply this knowledge in your field.

Psychrometrics is a branch of thermodynamics that studies air's physical and thermodynamic properties and the relationships between these properties. The word "psychrometrics" comes from the Greek words "psuchron," which means "cold," and "metron," which means "measure." Therefore, psychrometrics is the measurement of the properties of air, including temperature, humidity, and pressure.

One of the most essential tools used in psychrometrics is the psychrometric chart. The psychrometric chart is a graphical representation of the thermodynamic properties of air. It is a chart that displays the relationships between temperature, humidity, and pressure. The chart calculates the various properties of air, including the dew point, relative humidity, and enthalpy.

Download your Psychrometric Chart Here: https://www.insightusa.com/psychrometric-chart-pdf

To use the psychrometric chart, one must first determine the dry-bulb temperature, which is the air temperature as measured by a thermometer. Next, one must determine the wet-bulb temperature, which is the air temperature as measured by a thermometer with a wet wick. These two temperatures are then used to locate the point on the chart that represents the current state of the air.

Once the current state of the air has been located on the psychrometric chart, it is possible to calculate various properties of the air, such as the dew point, relative humidity, and enthalpy. The dew point is the temperature at which the air must be cooled for water vapor to condense into liquid water. The relative humidity is the ratio of the amount of water vapor in the air to the maximum amount of water vapor that could be present at the current temperature and pressure. Enthalpy is the total heat content of the air.

Understanding the psychrometric chart is essential for anyone involved in the design, installation, and maintenance of air conditioning and ventilation systems. It is also essential for anyone working in meteorology, agriculture, and industrial processing, where the properties of air play a crucial role.