VAV box minimum flow setting

[mech4321]

I am wondering if VAV boxes minimum flow setting can be adjusted higher without rebalancing the min/max with a TAB contractor. For example, adjusting via the BAS the minimum flow from 25% to 35% to increase the outdoor air fraction in the spaces. The box sensor will be able to read the flow. An engineer came up with the necessity to appeal to a TAB contractor to rebalance the boxes in this case. Why?

 

[apollowolfe]

The TAB is just in place to get the system to meet the design. In my experience doing building inspections, facility management will change everything around with no regard for code or design conditions.

Why does the minimum need changed does it not meet the ventilation requirement? If it was designed to meet ventilation at 25% just leave it be and let it ramp up to match loads. Why not take in more outdoor air to increase your supply air fraction?

 

[HVAC-Novice]

What problem are you trying to resolve?

And this needs much more explanation from your side. How does fresh air get into the AHU, is that metered based on measurements? Do the rooms have any CO2 sensors or other means to adjust ventilation based on demand? Are you trying to adjust one or all VAV boxes? Technically, each VAV zone should have a specific minimum flow setting, not just a flat 25 or 35%. Why did this come up to begin with?