AHU coils

Have you ever come across AHU units? If you have, you would probably like to know more about AHU coils and what they entail. In case you have never crossed paths with this term, we can also help you understand what it is all about.

We will explore what AHU coils are, how they work, their differences from Fan Coil Units (FCU), maintenance requirements, and much more. Read on to find out more about AHU coils.

What is an AHU coil?

An AHU coil is a component of the air handling unit (AHU) that cools or heats the air in a room to enhance comfort. AHU coils are mostly made of copper or aluminum tubing, which enhances the heat transfer rate between the two fluids in the air handling unit.

AHU coils can either be direct expansion coils, hot water coils, or chilled water coils. These coils work hand-in-hand with other HVAC components to regulate temperature, humidity, and air quality.

How do AHU coils work?

AHU coils function on the principle of heat transfer. When air passes through the coils, the coils either cool the air by absorbing heat or heat the air by transferring heat, depending on your system’s requirements.

In cooling mode, a refrigerant flows through the AHU cooling coil, which absorbs heat from the air in your room. The cooling coil also dehumidifies the air in the space, improving air quality. In the case of a chilled water system, the chilled water flows through the AHU coil, absorbing the heat from your indoor air to provide a cooling effect. 

In heating mode, a hot water AHU heating coil uses hot water to heat your indoor air for your specific heating needs.

What is the difference between AHU and FCU?

An air handling unit AHU is a component of your HVAC system that cools or heats air and distributes it in your space using ductwork. A fan coil unit, on the other hand, is an independent cooling or heating system that is used to cool smaller spaces without the use of ductwork.

The AHU is used to heat or cool the entire building, while an FCU can heat or cool smaller spaces in your building. An air handling unit system can circulate air both on the inside and outside of your building, while an FCU system only circulates air contained within a room.

What are the types of AHU coils?

AHU coils come in various types, each engineered to meet specific heating or cooling requirements. Your choice depends on the system’s design and the building’s needs. Here are some common types of AHU coils:

Chilled water coils

These coils use chilled water to cool the air. They are common in air conditioning systems. They are essential for cooling the air in warm weather.

Hot water coils

These coils use hot water to provide heating. An AHU heater coil is common in heating applications. It can also be part of a dual-coil system where one coil is for heating and the other for cooling.

Direct Expansion (DX) coils

Direct Expansion (DX) coils use a refrigerant to cool the air directly. You can find these coils in smaller HVAC systems. They are particularly efficient for cooling.

AHU evaporator coils

Evaporator coils, also known as cooling coils, are used in air conditioning systems to absorb excess heat from the air, thus cooling it down. They work alongside AHU condenser coils to facilitate the cooling cycle in refrigeration systems.

Where are AHU coils used?

The following are some applications of AHU coils.

  1. Hotel industry for dehumidification and air conditioning
  2. Healthcare sector to control humidity levels for effective sanitation and hygiene
  3. Government offices for effective heating and cooling
  4. Petrochemical industries for providing effective cooling and heating for industrial
  5. processes
  6. Institutions to enhance comfort with efficient heating and cooling solutions
  7. Pharmaceutical industry to regulate drug temperature and maintain a sterile environment
  8. Data centers to protect sensitive electronic equipment
  9. Food processing facilities to maintain controlled environments for food safety and quality

How are AHU coils maintained?

AHU coils require regular maintenance to maintain their effectiveness. Below is how you can maintain your AHU coils.

Regular cleaning

Over time, your AHU coils can collect dirt, grime, mildew, or mold, which can affect the efficiency of your system. Your system can begin to overwork or produce low-quality air when your coils become dirty. To ensure your system continues to work effectively, consider regularly cleaning your AHU coils.

If you can’t handle the cleaning yourself, you can always hire an expert to professionally clean your AHU. A professional will know how to effectively clean your coils and check for drain line blockages.

Check for leaks and corrosion

Regularly inspect the coils for signs of leaks or corrosion. Leaks can lead to refrigerant or water loss, while corrosion can weaken the AHU coil’s structure. Address these issues promptly to prevent further damage.

Inspect coil fins

The fins on the coils are delicate and can easily become bent or damaged. Ensure that the fins are straight and free from damage. Bent fins can obstruct airflow and reduce heat transfer.

Clean and replace air filters

Clean and replace air filters as needed to ensure adequate airflow and prevent debris from reaching the coils. Clogged filters restrict airflow, leading to reduced efficiency and strain on the AHU coils.

Check fluid levels

If your AHU uses coils that contain refrigerants or heating fluids, check the condition and levels of these fluids. Low levels or leaks can affect the coil’s heating or cooling capacity.

Routine servicing

Consider investing in a routine maintenance plan to avoid costly repairs or system breakdowns. You can hire a professional to perform routine check-ups on your air handling unit coils to determine their condition. A professional can also examine your system for other issues that might affect the efficiency of your unit. Regularly servicing your AHU coils can help you extend the life of your system.

Signs of a Faulty Air Handling Unit Coil

A faulty AHU coil can lead to system inefficiency and discomfort in the UAE’s extreme weather conditions. Common signs of a faulty AHU coil include:

  • Reduced Heating or Cooling Efficiency: If your HVAC system no longer maintains the desired temperature, it could be due to a faulty coil.
  • Strange Sounds: Unusual noises, such as hissing or gurgling, can indicate a problem with the coils.
  • Water Leaks: Leaking water around the AHU is a clear sign of a problem, possibly a damaged cooling coil.
  • Frozen Coils: In cooling coils, ice formation is a clear sign of trouble and can reduce the coil’s effectiveness. Frozen coils can cause reduced airflow and cooling capacity.
  • Increased Energy Bills: A faulty coil can lead to increased energy consumption, resulting in higher utility bills.

FAQs About AHU Coils

Do Air Handling Units Have Refrigerant?

AHU coils can use refrigerant as the heat transfer fluid, but they can also use hot or chilled water, depending on the specific heating or cooling requirements.

Can an AHU Work Without a Chiller?

Yes. An AHU can work without a chiller, depending on the system’s specific design and requirements. While a chiller is commonly used to provide cooling by circulating chilled water, alternative methods like Direct Expansion (DX) cooling coils can be used in AHUs.

AHU Coils

Coils are important components of your Air Handling Unit that facilitate the heat exchange process in several commercial and industrial applications. Constant cleaning and maintenance can help maximize the efficiency of your system.

You can choose direct expansion coils, chilled water coils, or hot water coils, depending on your application. Be sure to purchase your coil from a reliable AHU coil manufacturer like Al Tabreed for a longer service life. If you require more assistance, don’t hesitate to reach out to us today.