Tuesday, September 3, 2024

The importance of proper air handling unit sizing

 The essential component of any HVAC system is the air handling unit (AHU) of a building, which provides conditioned air throughout. The dimensions of the AHU should not only accommodate the available space in the plantroom and adhere to building requirements, but also accommodate the filters, heat exchangers, and maintenance and fan access sections.


Correctly sizing this critical component is essential for efficient, effective environmental control. There are a few factors to take into account while determining the AHU's size.


  • Match capacity to demand

Oversized or undersized AHUs cause problems. It is too small, and areas won't reach the desired temperatures, frustrating occupants. Oversized wastes energy by short-cycling compressors excessively. Consult reputable air handling unit UAE suppliers to accurately determine a space's heating/cooling demand before selecting nominal unit capacity. 


  • Factor runtime needs

AHU sizing also affects runtime. Short, frequent cycles strain components unnecessarily versus steady runtime. Consider internal/external heat loads plus desired runtime when selecting an air handling unit best suited to duty cycle needs rather than just peak capacity alone. Longer cycles ease the strain on parts.


  • Ensure adequate airflow

Design supply air volume specifically for the zone's ventilation requirements. Under-airflow risks compromising indoor air quality and thermal comfort. Over-ventilation wastes conditioned air and energy. Careful calculations factoring zone cubic footage and air changes per hour are needed from air handling unit suppliers.


  • Consider ductwork design

The unit selected must be appropriately sized for static pressure and friction losses within the duct system laid out for the building. Oversized blowers push more air volume than ducts can handle, straining duct joins prematurely. Design static pressure drops into unit selection.

  • Allow operational flexibility

Variable speed fans and compartmentalized coils enable partial load operation down to 10-20% capacity as conditions allow. This saves energy versus cycling large AHUs on and off in part-load situations. Consider future flexibility when selecting air handling units from suppliers in the UAE.


Properly sizing AHUs involves thorough heat/ventilation load analysis and factoring installation variables. The benefits are optimized comfort, efficiency, and equipment/component lifespan. Rely on qualified engineers from reliable manufacturers like Trosten Industries whose Eurovent-certified AHUs have the best mechanical performance.


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