How the VAV Box Affects IAQ

Facilities managers know the importance of maintaining the HVAC system in their buildings. These systems provide fresh clean air and control temperatures and that keeps building occupants comfortable. Commercial buildings have different needs than homes and their HVAC systems adjust performance based on thermal zones. This is done with a VAV box. This system is more efficient, but it’s important to consider how the VAV box affects IAQ as well.

What is a VAV System? 

In HVAC, a Constant Air Volume (CAV) system delivers a continuous supply of air. This is the HVAC system found in many homes. For commercial HVAC systems, however, it’s not as simple as the on and off settings you find in home systems. In larger buildings with many rooms of different sizes, this system is not effective in maintaining comfortable temperatures throughout. Therefore, it’s important to use a system that varies airflow. That’s what the Variable Air Volume (VAV) does. It varies the airflow but at a steady temperature.

What is a VAV Box?

A simple VAV system supplies air through a single duct. A multiple-zone VAV system, on the other hand, serves numerous areas of the building with multiple ducts. A VAV box controls the airflow for these different zones. Located in the air ducts, the VAV box connects to a central system. The zone temperature control manages the temperature in each area using either a thermostat or sensor which sends a signal to the VAV controller.

The VAV box contains several important parts. The three main parts of the VAV box include:

1. Airflow sensor – to measure the airflow and adjust the damper to maintain flow rate
2. Damper – controls the amount of air flowing through the ducts
3. Fan – assists in maintaining flow rates

The VAV system includes:

• Air handling unit
• Primary ductwork
• Terminal unit
• The ductwork/air distribution that serves each zone

Each of these parts works to provide the right amount of air to a specific room and at the right temperature.

How the VAV box affects IAQ

From temperature control to reduced wear, the VAV system has several advantages over CAV.  A cleaner system gets better results. Therefore, when operating at peak performance, the VAV box affects IAQ in a positive way.

Precise Temperature Control

A varied system, controlled by a VAV box, offers more temperature control. For example, the CAV system runs the fan and compressor at full capacity to meet the desired temperature. It shuts off once this temperature is reached. This cycling between on and off causes the temperature to shift up and down. On the other hand, with the VAV box, the fan’s speed changes according to the actual space temperature. This allows for more space temperature control. Because the fan runs less often with a VAV system, there’s less fan noise as a result.

Reduced Compressor Wear

The VAV box system reduces wear and tear because it allows for adjustments in control of the compressor. When the system runs at high speed after cycling off and then on again, this puts a strain on the compressor. Over time, this leads to more maintenance and repair calls. IAQ also suffers when the system is not running at top efficiency.

Lower Energy Consumption

Better control reduces the amount of energy needed to run the system. The compressor also runs better, as mentioned above, and the fan uses less energy as well. This lowers energy and operating costs and strengthens the bottom line. 

How the VAV Box Affects IAQ with Passive Dehumidification

More dehumidification results from VAV air box systems. In short, reduced airflow means that air is exposed to the cooling coils for longer. As a result, more moisture condenses on the coil thus dehumidifying the air. 

Maintaining VAV Boxes 

Maintaining the VAV box means keeping up with inspections, cleaning, and maintenance on the whole HVAC system. WTI | Pure Air Control offers services and methods to keep HVAC systems running at peak efficiency.

For example, our HVAC Hygiene Assessment provides precise details about the impact a system has on IAQ. It includes a visual inspection of all parts of the air handling unit. By analyzing samples collected from the AHU, we determine the impact, if any, of the airflow across the coils. Testing is also done to look for bacteria and fungi. A final report provides details on the results as well as advice to improve the system.

As well, our PURE-Duct method goes deep inside the ductwork to remove dirt and debris. We do this with high-pressure air turbulence. A powerful vacuum system with a HEPA filter collects dirt and debris.

Learn More About How the VAV Box Affects IAQ

In conclusion, keeping your HVAC system in top working order saves money and keeps building occupants comfortable. It also lowers the risk of virus transmission and improves air quality. To learn more about our IAQ services, contact WTI – Pure Air Control today.