RACA Journal March 2024 RACA_March_2024_digital | Page 31

Feature iv . Testing and commissioning :

• Thorough testing : Conduct rigorous testing of the assembled AHU to ensure compliance with design specifications . This includes assessing airflow rate , temperature and humidity control , and overall unit performance .

• Commissioning : Start up the AHU and adjust controls to ensure it operates according to the design brief provided by the consultant .

Following these sequential steps , engineers can design and construct a custom AHU tailored to the application ' s requirements , ensuring optimal performance and efficiency .

5 . The relationship between AHUs and VRFs AHUs connected to variable refrigerant flow ( VRF ) systems enable the execution of cooling , heating and dehumidification with the latest energy efficiency offered by the variable refrigerant flow condensing unit . These systems are generally more energy-efficient than conventional AHUs traditionally connected to two-pipe or four-pipe chillers . This heightened efficiency is attributed to their ability to adjust refrigerant flow according to demand and operate at higher suction temperatures .

6 . What are the common problems associated with AHUs ? AHUs embody intricate systems comprising various components , which may encounter a spectrum of challenges by their nature . Here , we highlight some prevalent issues associated with AHUs , acknowledging that this list can be expansive depending on the specific components included in the AHU :

I . Airflow and pressure challenges a . Clogged air filters b . Malfunctioning dampers

II . Component failures

Large Glycol AHU .

minimising energy costs . Here are essential steps you can take to achieve this :

Prioritise cleanliness : 1 . Filters :

• Regularly inspect and replace air filters according to the manufacturer ' s recommended schedule . Clogged filters impede airflow , reducing efficiency and compromising air quality .

2 . Coils :

• Clean both heating and cooling coils as needed . Dust and debris accumulation hinders heat transfer and efficiency . Utilise professional cleaning methods or refer to your AHU manual for specific instructions .

3 . Drain pans and drain piping :

• Ensure proper drainage to prevent leaks and mold growth . Routinely clean drain pans and piping , removing debris and checking for clogs .

Mechanical maintenance : 1 . EC plug fans :

• Periodically clean fan blades to eliminate accumulated dust and debris , enhancing airflow and preventing imbalance issues .

2 . External components :

• Wipe down the exterior of the fan , including the housing and accessible parts , to maintain a clean and efficient operation .

3 . Dampers :

• Confirm smooth damper operation without obstructions – lubricate damper linkages when necessary .

4 . Electrical connections :

• Regularly check for loose connections , frayed wires or potential electrical hazards .