How Chiller, AHU, RTU work - working principle Air handling unit, rooftop unit hvac system

The Engineering Mindset2 minutes read

Chillers are vital for air conditioning, with water-cooled and air-cooled varieties used to generate chilled water by removing heat. Air handling units and rooftop units play key roles in circulating chilled water and conditioning air for distribution in buildings.

Insights

  • Chillers come in two main types, air cooled and water cooled, with water cooled chillers typically located in basements and requiring cooling towers, while air cooled chillers are usually placed on rooftops or outside.
  • Air handling units (AHUs) and rooftop units (RTUs) are integral components of air conditioning systems, with AHUs distributing air within buildings and often connected to central plant units, while RTUs are self-contained HVAC units located on roofs, providing air conditioning for small commercial properties.

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Recent questions

  • What are chillers used for?

    Chillers are used to generate chilled water for air conditioning by collecting unwanted heat.

  • Where are water cooled chillers typically located?

    Water cooled chillers are typically located in the basement.

  • What is the difference between air handling units and rooftop units?

    Air handling units distribute air within buildings, while rooftop units are self-contained HVAC units located on roofs.

  • Where can air handling units be located?

    Air handling units can be located inside buildings, rooftop plant rooms, or on roofs.

  • How do rooftop units differ from air handling units?

    Rooftop units (RTUs) are always situated on rooftops and contain their own refrigeration system for cooling.

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Summary

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Types and Functions of Building HVAC Units

  • Chillers are used to generate chilled water for air conditioning by collecting unwanted heat, with two main types: air cooled and water cooled.
  • Water cooled chillers are typically located in the basement and require a cooling tower to reject heat, while air cooled chillers are usually found on rooftops or outside.
  • Chillers circulate chilled water to air handling units and fan cool units, where the air is forced across heat exchangers to extract heat before distribution.
  • Air handling units (AHUs) distribute air within buildings, often connected to central plant units or split AC systems, and are connected to duct work for air circulation.
  • Rooftop units (RTUs) are self-contained HVAC units located on roofs, common in small commercial properties, with components like dampers, filters, heating and cooling coils, and fans.
  • AHUs are typically located inside buildings but can also be found in rooftop plant rooms or on roofs, while RTUs are always situated on rooftops.
  • Both AHUs and RTUs clean and condition air for distribution within buildings, with AHUs often connected to central plant units and RTUs containing their own refrigeration system for cooling.
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