BAS-310 Visual Aid Library
Figure-use rule
Each figure is an orientation and reasoning aid, not a project drawing. Learners must pair it with the current sequence, point list, wiring/piping documents, manufacturer instructions, and as-found evidence.
Normal-rule anchor
The BAS technician organizes evidence and system response; the technician does not diagnose illness or certify safety.
Case overlay
Several occupants report dizziness after a chemical spill odor appears near an air intake.
Calculation/evidence callout: Count affected locations/times only as descriptive evidence; do not convert reports into exposure dose or medical conclusions.
Normal-rule anchor
No single BAS sensor is an IAQ meter, and acceptable temperature does not prove acceptable IAQ.
Case overlay
An odor appears only when a nearby exhaust fan and certain wind direction coincide.
Calculation/evidence callout: Build a source-pathway-time matrix and compare coincident events without claiming causation beyond evidence.
Normal-rule anchor
Ventilation quantity comes from applicable project/adopted criteria and verified system evidence, not a guessed universal value.
Case overlay
The outdoor-air damper command is open but the intake is blocked by construction material.
Calculation/evidence callout: Reconcile design, scheduled, TAB, controller, and current evidence values with units and source identity.
Normal-rule anchor
DCV may reset ventilation within its approved method; it does not permit ventilation below applicable minimum or replace source control.
Case overlay
A conference room CO2 rises during use, but the system outdoor-air flow station is stale.
Calculation/evidence callout: Calculate supplied zone/system outdoor airflow and compare scheduled, design, TAB, and controller values; state uncertainty.
Normal-rule anchor
CO2 can support a ventilation investigation when occupancy, outdoor reference, sensor quality, and system mode are known.
Case overlay
CO2 is high in one room while adjacent rooms with the same air system remain normal.
Calculation/evidence callout: Calculate indoor-outdoor differential, rate of rise/decay, lag, and data age without inferring total IAQ or health safety.
Normal-rule anchor
RH changes with temperature; dew point and humidity ratio help separate moisture content from temperature effect.
Case overlay
A cold supply diffuser sweats during humid weather while space RH appears moderate.
Calculation/evidence callout: Calculate dew point, humidity ratio, and margin between surface temperature and dew point using approved tools/data.
Normal-rule anchor
A normal HVAC pressure strategy must not be used to test, override, or reinterpret smoke-control or regulated-space requirements.
Case overlay
A lobby door is difficult to open when multiple exhaust systems run on a cold windy day.
Calculation/evidence callout: Calculate supplied air-balance difference and interpret differential-pressure sign/reference with wind and door context.
Normal-rule anchor
Filter class, installation seal, airflow, loading, system capacity, and application all affect actual performance.
Case overlay
A higher-efficiency filter is installed and supply airflow drops while bypass gaps remain visible.
Calculation/evidence callout: Calculate filter pressure-drop change and compare to exact manufacturer/project criteria and fan/system response.
Normal-rule anchor
Controller airflow and calculations are not certified TAB; instrument/method, conditions, uncertainty, and qualified report authority matter.
Case overlay
The TAB report lists 600 cfm, the controller maximum is 800 cfm, and the point name matches a different box.
Calculation/evidence callout: Compare design, TAB, controller, and current values by identity, units, density basis, uncertainty, and percent difference.
Normal-rule anchor
Responsible IAQ communication is precise about evidence and uncertainty and never upgrades a BAS inference into a health or safety certification.
Case overlay
The immediate ventilation fault is corrected, but odor source and occupant health concerns remain outside BAS scope.
Calculation/evidence callout: Reconcile complaint windows, valid data windows, actions, verified outcomes, unresolved questions, owners, and follow-up dates.