ClassX Video Lessons Youtube Channel The Engineering Mindset How Chiller, AHU, RTU work – working principle Air handling unit, rooftop unit hvac system
Welcome to an exploration of the key components in HVAC systems: chillers, air handling units (AHUs), and rooftop units (RTUs). This guide will help you understand how each unit functions, their differences, and where they are typically located within a building.
Chillers play a crucial role in generating chilled water, which is essential for air conditioning by removing excess heat from a building. There are two primary types of chillers: air-cooled and water-cooled. The distinction between them lies in how they expel heat from the building.
Water-cooled chillers are generally situated in the basement or the lowest floor of a building. They require a cooling tower to dissipate heat. These chillers produce chilled water that circulates to AHUs and fan coil units, which then distribute the cooled air throughout the building. The process involves chilled water absorbing unwanted heat, which is then transferred to the chiller’s condenser via a refrigerant loop. The condenser releases this heat into the condenser water loop, which connects to the cooling tower. The cooling tower uses ambient air to expel the heat into the atmosphere.
Water-cooled chillers are ideal for large commercial buildings with significant cooling needs. You can identify such buildings by the presence of cooling towers, often located on the roof. Multiple chillers and cooling towers are common to ensure redundancy and handle varying cooling demands.
Air-cooled chillers are typically found on rooftops or outside buildings. They also produce chilled water for AHUs and fan coil units. The process involves air circulating over heat exchangers within these units, where unwanted heat is transferred to the chiller’s condenser. A fan then blows air across the condenser to remove the heat, classifying it as an air-cooled chiller. These chillers are prevalent in medium to large commercial properties.
Both AHUs and RTUs are designed to distribute air within a building, but they differ in their heating and cooling methods.
AHUs are usually located inside buildings, although they can also be found in rooftop plant rooms. They distribute air to specific areas within a building. In modern buildings, multiple smaller AHUs are often used to enhance indoor air quality and energy efficiency. AHUs are typically connected to a central plant, such as a chiller, and may also use split AC units or district cooling networks.
AHUs connect to ductwork, providing a defined path for air travel. They draw in fresh air using a fan, filter it to remove dust and dirt, and then pass it through cooling and heating coils before distributing it throughout the building.
RTUs are always located on rooftops, as their name suggests. They are common in shops and small commercial properties due to their compact and straightforward design. RTUs distribute conditioned air to specific building areas and are connected to ductwork for air distribution. They typically have their own refrigeration system for cooling and may include a heat source, such as a gas-fired heater or electric heat pump.
RTUs house all necessary components, including dampers for airflow control, filters for air cleaning, and heating and cooling coils. Fresh air is drawn in by a fan, filtered, conditioned, and then pushed into the building. Used air is collected and returned to the RTU for either ejection or recirculation.
Understanding these components and their functions is essential for anyone involved in building management or HVAC system design. Each unit plays a vital role in maintaining comfortable and efficient indoor environments.
Engage with an online simulation tool that allows you to manipulate and observe the functions of chillers, AHUs, and RTUs within a virtual building. This activity will help you visualize how these components interact and affect the overall HVAC system performance. Experiment with different configurations to see the impact on energy efficiency and indoor climate control.
Analyze a real-world case study of a commercial building’s HVAC system. Focus on the selection and placement of chillers, AHUs, and RTUs. Discuss the reasons behind choosing specific types of chillers (air-cooled vs. water-cooled) and the strategic location of AHUs and RTUs. This will enhance your understanding of practical applications and decision-making processes in HVAC design.
Organize a field trip to a local commercial building with a complex HVAC system. Observe the installation and operation of chillers, AHUs, and RTUs. Interact with facility managers to gain insights into the maintenance and challenges associated with these systems. This hands-on experience will solidify your theoretical knowledge with real-world observations.
Work in groups to design an HVAC system for a hypothetical commercial building. Consider factors such as building size, location, and climate. Decide on the types of chillers, AHUs, and RTUs to use, and justify your choices. Present your design to the class, highlighting the expected efficiency and comfort levels your system will provide.
Participate in a workshop where you can disassemble and reassemble models of chillers, AHUs, and RTUs. Learn about each component’s function and how they contribute to the system’s overall operation. This hands-on activity will deepen your technical understanding and improve your ability to troubleshoot and maintain HVAC systems.
Sure! Here’s a sanitized version of the YouTube transcript:
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Hello everyone, Paul here from TheEngineeringMindset.com. In this video, we will explore the differences between chillers, air handling units (AHUs), and rooftop units (RTUs). We will cover how to recognize each unit, the basics of how they work, the differences between them, and where to locate them.
Before we dive into the content, I want to take a moment to thank our partners at Danfoss for sponsoring this video. Since we are discussing air conditioning systems, it’s worth mentioning that Danfoss offers solutions to help increase efficiency and ensure compliance with refrigerant regulations across various types. They have a deep understanding of chillers, AHUs, and RTUs, along with a broad portfolio of parts to enhance performance and reduce energy costs. You can find out more about their air conditioning solutions at AirConditioning.Danfoss.com.
First, let’s look at chillers. Chillers are used to generate chilled water, which is pumped around the building to provide air conditioning by removing unwanted heat. There are two main types of chillers: air-cooled and water-cooled. The terms “water-cooled” or “air-cooled” indicate how the chiller’s condenser rejects heat from the building.
Water-cooled chillers are typically located in the basement or on the lowest floor of a building. This type of chiller requires a cooling tower to reject heat. The chiller produces chilled water and circulates it to air handling units and fan coil units, which distribute air throughout the building. The air passes over heat exchangers containing chilled water, extracting unwanted heat before being distributed. The heat collected in the chilled water loop is pumped back to the chiller, where it is transferred to the condenser via a refrigerant loop. The condenser absorbs this heat and transfers it to the condenser water loop, which runs between the chiller and the cooling tower. The cooling tower then uses ambient air to extract and reject the unwanted heat into the atmosphere.
Water-cooled chillers are commonly used in large commercial properties with high cooling loads. You can identify a building with a water-cooled chiller by the presence of a cooling tower, usually located on the roof. It’s common to have multiple chillers and cooling towers for redundancy and to accommodate variations in cooling demand.
Air-cooled chillers, on the other hand, are typically located on the roof or outside the building. They also generate chilled water, which is circulated to air handling units and fan coil units to cool the building. The air is forced to circulate and passes over heat exchangers within the air handlers and fan coil units. The unwanted heat is transferred to the condenser of the chiller from the evaporator via a refrigerant loop driven by the compressor. In this case, the fan blows air across the condenser to remove the unwanted heat, making it an air-cooled chiller. Air-cooled chillers are usually found in medium to large commercial properties.
Now, let’s discuss AHUs and RTUs. Both systems serve a similar purpose and can look quite alike. They are used to distribute air around the building and contain fans to achieve this. Both take in fresh ambient air, filter it, and then heat or cool it to meet the building’s demands. The main difference lies in how the air is heated or cooled.
Air handling units (AHUs) are typically located inside the building, although they can also be found in rooftop plant rooms. Their purpose is to distribute air around defined areas within the building. Sometimes, one AHU will supply the entire building, but it’s common in newer buildings to have multiple smaller AHUs for better indoor air quality and energy savings. AHUs are usually connected to a central plant, such as a water or air-cooled chiller, and may also use split AC units or be connected to district cooling networks.
AHUs are connected to ductwork, which provides a defined route for air to travel. In simple terms, an AHU uses a fan to draw in fresh outside air, which passes through filters to remove dust and dirt. The air then goes through cooling and heating coils, typically fed from central plant units, before being distributed throughout the building.
Rooftop units (RTUs) are always located on the roof, as the name suggests. They are common in shops and small commercial properties due to their simplicity and compact design. RTUs distribute conditioned air around defined areas within a building and are connected to ductwork for air distribution. They typically have their own indoor refrigeration system for cooling and may also include a heat source, such as a gas-fired heater or electric heat pump.
RTUs house all components within the unit, including dampers to control airflow, filters for air cleaning, and heating and cooling coils. The fresh ambient air is drawn in by the fan, passes through the filters, and is conditioned before being pushed into the building. Used air is collected and returned to the RTU for ejection or recirculation.
That’s it for this video! I want to extend another special thanks to our sponsor, Danfoss. Don’t forget to check out their extensive range of air conditioning parts and solutions at AirConditioning.Danfoss.com. If you enjoyed this video and found it helpful, please hit the like, subscribe, and share buttons. You can also follow us on social media and visit our website, TheEngineeringMindset.com. Thank you for watching!
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This version removes any informal language and maintains a professional tone while preserving the essential information.
Chillers – Devices used in HVAC systems to remove heat from a liquid via a vapor-compression or absorption refrigeration cycle. – The engineering team installed new chillers to improve the building’s cooling efficiency.
AHUs – Air Handling Units, which are devices used to regulate and circulate air as part of a heating, ventilating, and air-conditioning system. – The maintenance crew performed a routine check on the AHUs to ensure optimal air distribution throughout the facility.
RTU – Rooftop Unit, a type of HVAC system installed on the roof of buildings to provide heating and cooling. – The engineers decided to upgrade the RTU to enhance the building’s energy efficiency and climate control.
Cooling – The process of removing heat from a space or substance to lower its temperature. – The cooling system in the laboratory is designed to maintain a constant temperature for sensitive experiments.
Air – The invisible gaseous substance surrounding the earth, a mixture mainly of oxygen and nitrogen, used in HVAC systems for ventilation and temperature control. – Proper air circulation is crucial in maintaining indoor air quality and comfort in large office buildings.
Heat – A form of energy associated with the movement of atoms and molecules in any material, often transferred in HVAC systems to maintain desired temperatures. – The heat generated by the industrial equipment is efficiently dissipated using advanced thermal management systems.
Refrigerant – A substance used in a heat cycle to transfer heat from one area and remove it to another, commonly used in air conditioning systems. – The choice of refrigerant in the cooling system significantly affects its environmental impact and efficiency.
Ductwork – A system of ducts used to deliver and remove air in HVAC systems, ensuring proper ventilation and temperature control. – The engineers redesigned the ductwork to improve airflow and reduce energy consumption in the building.
Efficiency – The ratio of useful output to total input in any system, often used to describe the performance of HVAC systems. – Increasing the efficiency of the HVAC system can lead to significant cost savings and reduced environmental impact.
Temperature – A measure of the warmth or coldness of an environment or substance, critical in engineering for controlling processes and systems. – Maintaining a stable temperature is essential for the optimal performance of electronic components in the server room.
