VAV / zone faults
Terminal boxes and the zones they serve.
Seven rules for variable-air-volume boxes: miscalibrated flow sensors, dampers and reheat valves that leak when closed, boxes stuck at minimum or maximum, and the single rogue zone that drags an entire air handler’s reset along with it. Individually small; across a few hundred boxes, not.
How to read it. A single VAV box over one day. The teal line is what the controller is asking the damper to do; the dashed green line is the airflow that should follow it. The red line is the airflow actually measured. When the damper opens fully and the flow does not move, the box is stuck.
The rules
- VAV-01
VAV airflow sensor miscalibrated
The VAV's airflow reading doesn't match what's expected from its damper position and the serving AHU's supply pressure.
Capacity-basedBAS trends - VAV-02
VAV damper leaking when commanded closed
Damper command is at minimum but measured airflow is well above minimum and the serving fan is running.
Capacity-basedBAS trends - VAV-03
VAV reheat valve leaking
Reheat valve is commanded closed but discharge-air temperature is rising above supply-air temperature.
Capacity-basedBAS trends - VAV-04
Zone outside its setpoint band
Zone temperature is sustained above the cooling setpoint or below the heating setpoint by more than the tolerance.
Diagnostic · comfortBAS trends - VAV-05
VAV reheat valve pegged but zone still cold
Reheat valve has been at 100% but the zone temp is still below the heating setpoint.
Capacity-basedBAS trends - VAV-06
VAV box stuck at min or max airflow
VAV airflow has been pinned at the minimum or maximum setpoint regardless of zone demand.
Capacity-basedBAS trends - VAV-07
Single zone driving AHU reset
One VAV is consistently the most-open box and is driving the AHU's SAT reset target colder or hotter than the rest of the building needs.
Capacity-basedBAS trends
See these rules run on your building.
Send twelve months of interval data and a BAS trend export. Energy Agent returns a ranked list of what is wasting money, what each item is worth per year at your tariff, and what to do about it.