George’s CBAS Tips, July 2020


Formulas and Calculations Help Feature

Formulas and Calculations is a Help feature that can be found on the System Menu > Help.  In older versions of CBAS, this was found directly on the System Menu. Currently, there are 4 entries..

The first one is a duct area calculator for use in the Cubic Feet per Minute (CFM) Calculation on a VAV or UNI-B. The VAV-B has this built into its VAV-B Utility Program that is used when you initially set it up. All you have to know is the dimensions of the duct and whether it is round or rectangular. Just enter the size and a value for the area will appear. You can also use this value as the Duct Size on a VAV template for a UNI-B.

The next calculation is CFM. The formula is given or you can just enter the round duct diameter and the pressure that is measured in Inches of Water Column to see the resulting CFM value..

The next helpful feature gives step by step instructions on making an Ethernet patch cable or crossover cable. This can be very helpful when you need to make up your own ethernet terminations..

There is also a wiring diagram and specification for a diode used in Access Control on an AC-3 or AC-5. Some door strikes can feedback voltage to the controller and cause a communications loss. A specific diode, 1N4007, can be placed across the terminals of the door strike on the AC-3 or AC-5.

More to explore