AHU/DX Units

AHU/DX Units

Air Handling Units (AHUs)

1. Definition

• An AHU is a central unit that conditions and circulates air as part of a heating or cooling system. It can be used for both heating and cooling purposes.

2. Components

• Fans: Circulate air throughout the system.

• Filters: Remove dust, pollen, and other particulates from the air.

• Coils: Typically include cooling coils (chilled water or DX coils) and heating coils (hot water or electric).

• Dampers: Control airflow and help in mixing outside air with return air.

• Controls: Regulate operation based on temperature, humidity, and occupancy.

3. Functionality

• Air Conditioning: AHUs condition air by cooling, heating, humidifying, or dehumidifying it before distributing it through ductwork.

• Ventilation: Introduces fresh outdoor air into the system to maintain indoor air quality.

4. Applications

• Commonly used in commercial buildings, shopping centers, hospitals, and industrial facilities.

Direct Expansion (DX) Units

1. Definition

• DX units are self-contained air conditioning systems that use refrigerant to cool or heat air directly without the need for chilled water or hot water systems.

2. Components

• Compressor: Compresses the refrigerant, raising its pressure and temperature.

• Evaporator Coil: Absorbs heat from the indoor air, causing the refrigerant to evaporate.

• Condenser Coil: Releases heat to the outside air, allowing the refrigerant to condense back into a liquid.

• Expansion Device: Regulates the flow of refrigerant into the evaporator coil.

3. Functionality

• Cooling: The refrigerant absorbs heat from the indoor air as it evaporates in the evaporator coil, providing cooled air to the space.

• Heating: Some DX units can reverse the refrigeration cycle, providing heating in cooler months.

4. Applications

• Widely used in residential and commercial air conditioning systems, including split systems and packaged units.

Comparison