In the HVAC industry, FCU (Fan Coil Unit), AHU, MAU, FFU and Heat Pump are the core components. Each device has different functions, principles and applicable scenarios. Understanding their differences and connections can not only help optimize system design, but also improve energy efficiency.
FCU (Fan Coil Unit)
Fan coil units serve as air conditioning terminals. They commonly control temperature in hotels and offices. Fans circulate air and adjust room temperature. Cold or hot water in the coil changes air temperature. Fans accelerate heat exchange between air and coils. This improves temperature control and enables fast cooling or heating.
Ultra-thin horizontal concealed fan coil
AHU (Air Handling Unit)
Air handling units (also called air conditioning boxes or wind cabinets) are important equipment in HVAC systems, responsible for regulating air temperature, humidity and cleanliness. Its working principle is to drive the air through the coil through the fan, causing the air to exchange heat and filter impurities in the air. Some units also have a fresh air function, which can handle the heat and humidity balance of fresh air and return air.
Air handling units come in various forms, including ceiling-mounted, vertical, horizontal and combined types. The ceiling-mounted type is often called a hanging cabinet, and the combined type is called a group cabinet. They are widely used in places that require precise temperature control and high cleanliness, such as shopping malls, hospitals and industrial plants.
FAU (Fresh Air Unit)
Fresh air units bring fresh air into spaces. They include home and commercial types. They extract air from outside. They remove dust, adjust humidity, and control temperature. Fans transport treated air into rooms. This replaces stale air and improves air quality.
FAUs focus on fresh air handling. AHUs also process return air. FAUs serve spaces needing fresh air, like schools, offices, and homes.
PAU (Pre-Cooling Air Unit)
Pre-cooling air units assist fan coil units. They process outdoor fresh air efficiently. They reduce the burden on indoor temperature systems. They improve air conditioning efficiency by adjusting fresh air. They perform pre-cooling or pre-heating as needed. Treated air flows to fan coil units for further adjustment. These units suit places with high fresh air loads. Examples include malls, airports, and office buildings.
MAU (Make-up Air Unit)
A make-up air unit is an air conditioning device that is specially used to provide fresh air. It can achieve constant temperature and humidity or simply provide clean air according to the use requirements. Its working principle is to extract air from the outside, and after a series of treatments (such as dust removal, humidity adjustment and temperature adjustment), the air is transported to the room through the fan to replace the original air.
MAUs suit places needing high air quality and comfort. These include hospitals, labs, and luxury hotels. Users can customize functions based on needs. More functions increase the cost.
HEPA (High-Efficiency Particulate Air)
These filters meet international standards for efficiency. They remove 99.97% of particles over 0.3 microns. They let air pass while blocking fine particles. They trap smoke, dust, and bacteria effectively. They act as strong barriers to air pollutants.
Their outstanding performance suits high-cleanliness environments. Operating rooms, labs, and semiconductor workshops use them. The aviation industry also relies on these filters for clean air.
FFU(Fan Filter Units)
The fan filter unit combines a fan and a filter. It forms a self-powered terminal purification device. It serves as a modular air supply device. The fan draws air from the top of the FFU. It passes the air through a HEPA filter. The filter removes particles for clean air. The device delivers air at 0.45m/s ±20% speed. The air flows evenly across the outlet surface.
Heat Pump
A heat pump is an energy-efficient heating and cooling device that transfers heat between indoors and outdoors by absorbing heat from air, water or geothermal heat. Its core principle is to use the physical properties of refrigerants to achieve heat transfer through evaporation and condensation processes.
Modern heat pumps achieve a COP above 3.0. Using 1 kW of electricity provides about 3 kW of heat. Heat pumps classify into air, water, and ground source types based on heat sources.
People use heat pumps in homes, offices, and industries. They save energy and reduce carbon emissions. In cold climates, air source heat pumps ensure stable heating. They rely on low-temperature technology for sustainable heating.
