Tag Archives: VAV

George’s CBAS Tips, November 2019

Using CO2 sensors with VAV-B

We were recently asked if it would be possible to utilize CO2 sensors with the VAV-B in order to control CFM setpoints. At this particular site, they want to add CO2 sensors to some of the VAV-Bs and command the CFM setpoint to the MAX CFM when CO2 gets above 800 ppm. In the VAV-B manual, there is a scenario that explains how to do this when the CO2 sensor is directly attached to the VAV-B. It is located at the end of the manual in Appendix B.

But what if you don’t have any available inputs on the VAV-B and your CO2 sensor is located on a different controller? In this case, the logic to make this happen will have to come from CBAS.

Continue reading George’s CBAS Tips, November 2019  

AHU Supply Temp Sets the Stage

In one of our recent articles, we discussed static pressure control and variable air volume (VAV) systems. We mentioned that by modulating the leaving air temp from an air handling unit (AHU) we can promote energy efficiency while also having an effect on static pressure. This time, we’ll look into how AHU supply temp sets the stage for efficient VAV operations.

Typically, VAVs are equipped with a means of reheating the supply air provided by the corresponding AHU. Continue reading AHU Supply Temp Sets the Stage

 

Static Pressure Control and VAV Operation

Static pressure is a key ingredient in a successful Variable Air Volume (VAV) system. It ensures that air flow will be available to enable the VAVs in a system to achieve their designed Cubic Feet per Minute (CFM) at maximum demand. Simply put, the push of the air must be greater than the resistance to the flow or no air will circulate through the ducts. Typically the setpoint for static pressure is determined through the course of the testing, adjusting, and balancing (TAB) at the end of a job. Continue reading Static Pressure Control and VAV Operation