5 Helpful AHU Troubleshooting Tips You Should Know

Before delving into the 5 helpful tips lets understand the basics of AHU starting with - What are AHU’S?

Before diving into troubleshooting tips, we need to understand what an AHU is and how it works. An Air Handling Unit (AHU) is a crucial component in many buildings, particularly in commercial and industrial settings. It's a piece of HVAC (Heating, Ventilation, and Air Conditioning) equipment that plays a vital role in maintaining a comfortable and healthy indoor environment. Here's a simplified overview of how they work: 

• The AHU draws in outside air through the intake, which is then filtered to remove dust and particulate matter (PM). 
• The filtered air is then heated or cooled using the coils, depending on the building's temperature requirements. 
• The conditioned air is then blown through the ductwork, distributing it throughout the building. 
• The AHU continuously monitors and adjusts the airflow, temperature, and humidity levels to maintain a comfortable and healthy indoor environment

AHU System: How it Works

An AHU functions similarly to a large air circulation unit, helping to maintain your building's thermal comfort. It draws in outside air, filters away the bad stuff, and then warms or cools it to the appropriate temperature. The air is then mixed with part of the existing air in the building to ensure proper air quality. The AHU system then blasts the air via a network of ducts to distribute it throughout the building. Sensors and computers manage the flow of air via the ducts, ensuring that the temperature and humidity are optimal. Finally, the AHU system removes stale air from the building and/or recirculates it through the system to make sure the air stays fresh and clean.

AHU Repair: Identifying Common Issues

Now that we have a basic understanding of what an AHU is and how it works, let's move on to identifying common issues with AHU's. Here are five helpful troubleshooting tips to help you identify and resolve common issues with your AHU system:

Tip 1: Check the Thermostat

One of the most common issues with AHU's is a faulty thermostat. A faulty thermostat can cause the system to malfunction, resulting in inconsistent temperatures and energy bills. To troubleshoot a faulty thermostat, check the battery level (if applicable) and ensure that the thermostat is set correctly. If the issue persists, consider replacing the thermostat or consulting a professional AHU technician such as ourselves. We offer a wide variety of CAREL thermostats for whatever project you are looking to undertake. Take a look at our wide range of CAREL.

(THB000AAW0 - Carel thT: Temperature Thermostat - Carel wall-mounting, 230 Vac)

Tip 2: Inspect the Air Filters

Dirty air filters can significantly reduce the efficiency and effectiveness of your AHU. Clogged filters can also cause the system to work harder, leading to increased energy bills and reduced air quality. To troubleshoot air filter issues, inspect the filters regularly and replace them as needed. It is recommended to replace filters every 1-3 months, depending on usage and environmental factors.

A standard control’s functionality is to provide a DP switch to measure the DP (differential pressure) across the filter bank in order to flag up an alarm on the control system for when a high pressure drop is detected, suggesting a dirty filter. The best products for this would be the 01APS-10U and PA-DPS-83. You can find these on our store by following the links below.

Belimo - 01APS-10U

Sontay - PA-DPS-83 

(On-site Commissioning)

Tip 3: Check the Electrical Connections

It might sound silly but faulty or incorrectly wired electrical connections can cause the AHU to malfunction or even shut down. To troubleshoot electrical issues, inspect the connections regularly and ensure that they are secure and free of corrosion.

                                                        (In this industry, we call this a spaghetti panel)

Tip 4: Inspect the DX Coils

DX coils are responsible for cooling or heating the air travelling through the air conditioning system. Dirty or clogged coils can reduce the system's efficiency and effectiveness. To troubleshoot DX coil issues, inspect the coils regularly and clean them as needed.

                      (i-ACS Commissioning for Pareto)                         

It is recommended to clean the coils every 3-6 months, depending on usage and environmental factors. Additionally, you can follow this step-by-step checklist in order to attempt to pinpoint the issue at hand:

1. Check the Coil Condition:

Inspect the coils for any signs of corrosion, rust, or mineral buildup.
Check for any cracks or damage to the coils.

2. Check for Debris:

Inspect the coils for any debris, such as leaves, twigs, or dirt, that may be obstructing airflow.
Use a soft-bristled brush or a vacuum cleaner to gently remove any debris.

3. Check for Proper Airflow:

Make sure the coils are not obstructed by any objects, such as plants or furniture.
Check that the coils are not clogged with debris or dirt.

4. Check the Coil Orientation:

Make sure the coils are properly oriented to ensure proper airflow.
Check that the coils are not bent or damaged.

5. Check the Coil Size:

Make sure the coils are the correct size for the AHU.
Check that the coils are not too small or too large for the AHU.

6. Check the Coil Insulation:

Make sure the coils are properly insulated to prevent heat loss.
Check that the insulation is not damaged or worn out.

7. Check the Coil Drainage:

Make sure the coils have a proper drainage system to prevent water accumulation.
Check that the drainage pipe is not clogged or blocked.

8. Check the Coil Electrical Connections:

Make sure the electrical connections to the coils are secure and not loose.
Check that there are no signs of electrical damage or wear.
A good AHU control system should detect alarm signals from the condensing unit - should it detect some fault with the system. To avoid this, make sure you choose the right control system. We believe we have the best solution for AHU control on the market. Find out more about our solution here.

9. Check the Coil Refrigerant Levels:

Make sure the refrigerant levels in the coils are within the recommended range.
Check that there are no signs of refrigerant leaks.

Tip 5: Check the Ductwork

Leaks in the ductwork can cause significant energy losses and reduce the overall efficiency of your AHU system. To troubleshoot ductwork issues, inspect the ducts for signs of damage, rust, or corrosion. Below, we have created a more detailed list of problems that can indicate issues with the Ductwork of your AHU.

(i-ACS commissioning for Ciat showcasing Ductwork)

1. Unusual Noises: If you notice unusual noises coming from your ductwork, such as hissing, banging, or rattling sounds.
2. Leaks: If you notice water or air leaks around the ducts.
3. Mould or Mildew: If you notice mould or mildew growing on the ducts or in the ductwork.
4. Reduced Airflow: If you notice a reduction in airflow from your AHU.
5. Increased Energy Bills: If you notice an increase in your energy bills, it may indicate a problem with the ducts, such as leaks or inefficiencies.
6. Unusual Odours: If you notice unusual odours coming from your AHU, such as mouldy or musty smells.
7. Dust and Debris: If you notice dust and debris accumulating in your ducts.
8. Pests: If you notice pests, such as rodents or insects, living in your ducts.
9. Rust or Corrosion: If you notice rust or corrosion on the ducts.
10. Age: If your ductwork is old or has been damaged

Conclusion

In conclusion, AHU’s are complex and require regular maintenance to ensure optimal performance. By understanding what AHU’s are and how they work, you can better troubleshoot common issues and resolve them effectively. Remember to check the thermostat, inspect the air filters, inspect the ductwork, inspect the condenser coils, and check the electrical connections regularly to maintain a comfortable and healthy indoor environment. Don't forget, we are always here to help, no matter how small the problem is.

Feel free to contact us at:

support@i-acs.co.uk
sales@i-acs.co.uk