Refurbishment of AHU’s and FAHU’s

Refurbishment of AHUs (Air Handling Units) and FAHUs (Fresh Air Handling Units) involves restoring, upgrading, or replacing key components to improve performance, efficiency, and extend the lifespan of the units. This is an excellent option when these units are older, inefficient, or require significant maintenance but are otherwise still structurally sound.

Below is a detailed guide to the refurbishment process for AHUs and FAHUs, covering what’s involved, benefits, and key considerations:

1. Refurbishment of AHUs (Air Handling Units)

Air Handling Units (AHUs) are central to HVAC systems, responsible for circulating and conditioning air in commercial, industrial, and residential buildings. Over time, these units may face issues like inefficient performance, wear and tear of components, or outdated technology, making refurbishment a cost-effective alternative to replacement.

Initial Inspection: A thorough inspection of the AHU’s components (e.g., fans, coils, filters, motors, dampers, insulation, and ducting) is conducted to assess the extent of damage or wear.
Performance Evaluation: Performance tests are done to check airflow, pressure drop, temperature, humidity, and energy consumption. This helps in determining which components need attention.
Structural Integrity Check: Assess the structural condition of the AHU’s casing, insulation, and frame. This ensures that the unit is safe to refurbish.

Fans and Motors: Replacing or repairing worn-out fans and motors is one of the most common refurbishment tasks. Upgrading to more energy-efficient motors (e.g., variable-speed drives) can improve performance and energy savings.
Coils (Cooling and Heating Coils) Dirty, clogged, or damaged coils can cause the AHU to operate inefficiently. Cleaning, repairing, or replacing coils can enhance heat transfer efficiency.
Filters: Old, clogged, or damaged filters are replaced with new, high-efficiency filters. This improves indoor air quality (IAQ) and system efficiency.
Dampers and Actuators: Inspect and repair or replace dampers and actuators to ensure proper air control and balancing. Damaged actuators can cause airflow issues and inefficiencies.
Insulation and Seals: Replacing worn insulation and seals can reduce energy losses and improve system efficiency by preventing air leakage.
Refrigerant Lines & Valves: If the AHU is part of a cooling system, the refrigerant lines, expansion valves, and associated components are checked for leaks or damage and replaced as needed.

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Variable Speed Drives (VSD): Install or upgrade to VSDs for fan motors. This helps in adjusting the airflow based on actual demand, leading to energy savings.
Control Systems & Automation: Upgrading the AHU’s control systems (e.g., Building Management System or BMS) to include smart sensors, humidity controls, and temperature monitoring can enhance automation and reduce operational costs.

Deep Cleaning: Thorough cleaning of the entire AHU is essential during refurbishment. This includes cleaning the coils, fans, ducts, and other internal components to remove dust, dirt, and microbial growth.
Microbial Control: Add microbial treatment (e.g., UV lights, anti-microbial coatings) to prevent mold, bacteria, and fungi growth in the unit, ensuring better air quality.

2. Refurbishment of FAHUs (Fresh Air Handling Units)

Fresh Air Handling Units (FAHUs) are specialized AHUs designed to bring fresh outdoor air into a building, typically for ventilation purposes. They may require refurbishment for similar reasons as AHUs, especially for buildings that require higher standards of ventilation or indoor air quality (IAQ).

Condition Evaluation: Inspect the FAHU for issues related to the intake of fresh air, filtration, and humidity control. Check for blockages in the intake, ductwork, and filters.
Airflow and Pressure Testing:Test the unit’s airflow to ensure that it meets the required ventilation standards, and check the static pressure across the system.
Compliance Check: Ensure that the FAHU meets any updated building codes or regulations related to air quality, energy efficiency, and safety.

Filters: Replacing filters in the FAHU is vital since they ensure the intake air is properly filtered before entering the building. High-efficiency particulate air (HEPA) filters or UV-C lamps for microbial control can improve IAQ.
Coils: If the FAHU includes heating or cooling coils (typically in HVAC systems where both ventilation and temperature control are required), these need to be checked for damage and cleaned or replaced if necessary.
Heat Exchangers (if applicable): If the FAHU has a heat recovery system, inspect and clean the heat exchangers. This could include plate heat exchangers (PHE) or rotary heat exchangers. These components play a crucial role in minimizing energy consumption by recovering heat from the exhaust air.
Fan Motors & Fans: Worn-out fan motors or fan blades can reduce airflow and increase energy consumption. These should be repaired or replaced, and fan speeds may be adjusted to meet demand.
Dampers and VAVs (Variable Air Volume): Inspect and repair dampers and variable air volume controllers to ensure they are functioning smoothly and providing the required ventilation.

Energy Recovery Systems: FAHUs often benefit from the addition or enhancement of energy recovery systems, such as heat recovery ventilators (HRVs) or energy recovery ventilators (ERVs). These systems help to pre-condition incoming fresh air by capturing heat from exhaust air, reducing heating/cooling energy loads.
Variable Speed Drives: As with AHUs, upgrading FAHUs with variable speed drives (VSDs) for fan motors can allow the system to adjust airflow based on real-time demand, improving energy efficiency.
Automation & Controls: Integrating or upgrading controls for better automation, such as CO₂ sensors or humidity controllers, ensures that the system adjusts based on the occupancy or needs of the building.

Deep Cleaning: Clean all internal components of the FAHU, including the fan blades, coils, filters, and heat recovery components. Cleaning is crucial for maintaining efficiency and preventing microbial growth.
Deodorization & Microbial Treatment: FAHUs are responsible for bringing in fresh outdoor air, and depending on the environment, microbial growth can occur. UV-C lights or other antimicrobial solutions can be added during refurbishment.

System Performance Testing: After refurbishment, test the FAHU to verify that it is delivering the required fresh air quantities and achieving the correct temperature, humidity, and filtration performance.
Air Quality Testing: Measure the indoor air quality (IAQ) to ensure that the fresh air handling system is meeting building standards for ventilation and air quality.