BAS-102 Reading Guide
How to use this reading guide
This is the concept-review layer for a 100% online course. Read each module before its lesson, complete the retrieval prompts without looking, then use the linked authoritative sources to verify project-specific editions, requirements, and manufacturer procedures.
Online evidence is not OJL: browser simulations, document cases, and isolated remote equipment build reasoning and documentation skill; supervised field performance is recorded separately.
Buildings, comfort, loads and HVAC purpose
Why it matters: HVAC manages heat, moisture, air quality, pressure, and time-dependent loads; a temperature complaint is not yet an equipment diagnosis.
Vocabulary and working scope
People/process; envelope; weather; solar; internal gains; temperature; humidity; air quality; pressure; ventilation; zones; sensible/latent load; schedules; occupancy.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A sunny west zone is hot at 3 PM while shaded zones are comfortable and the supply temperature is normal.
Calculation: Calculate temperature difference, simple heat-load comparisons from supplied data, percent time outside band, and reasonableness.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Heat, temperature, energy and measurement
Why it matters: Heat flows because of temperature difference, but rate depends on material, area, fluid flow, phase, and equipment; one sensor is limited evidence.
Vocabulary and working scope
Heat versus temperature; conduction; convection; radiation; sensible/latent; phase change; Btu; watt; ton; dry-bulb; wet-bulb awareness; sensor location/accuracy.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A coil has a large air temperature drop but low airflow, so space capacity remains poor.
Calculation: Calculate delta T, Q=mCpDeltaT from supplied values, Btu/h-to-watt/ton conversions, measurement error, and plausibility.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Air properties, psychrometric relationships and ventilation
Why it matters: Relative humidity depends on temperature; safe conclusions require temperature, moisture, airflow, mode, and location together.
Vocabulary and working scope
Dry air/water vapor; relative humidity; dew point; enthalpy awareness; sensible/latent; condensation; mixed air; outdoor/return/supply air; ventilation; filtration; pressure relationships.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A space is cool but clammy after a cooling coil cycles at low airflow and poor condensate removal.
Calculation: Calculate mixed-air temperature from supplied flows, moisture/temperature comparisons, ventilation percentage, and dew-point margin from supplied data.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Airside equipment and airflow path
Why it matters: Command, fan proof, airflow, pressure, temperature, and space response are separate evidence layers.
Vocabulary and working scope
AHU; RTU; MAU/DOAS awareness; fan; filter; coil; damper; mixing box; duct; diffuser/return; static pressure; airflow; economizer; frost/smoke boundaries.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A supply fan is commanded on and proven, but airflow is low because filters load and dampers are closed.
Calculation: Calculate CFM relationships from supplied data, airside heat Q=1.08 x CFM x DeltaT where applicable, outdoor-air fraction, and pressure/flow comparisons.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Refrigeration cycle, packaged cooling and heat pumps
Why it matters: The learner does not diagnose refrigerant charge from BAS data alone; only qualified technicians perform refrigerant and energized service procedures.
Vocabulary and working scope
Compressor; evaporator; condenser; metering device; refrigerant state; heat absorption/rejection; superheat/subcooling awareness; packaged unit; reversing valve; defrost; safeties.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A heat pump heats normally, then produces cool air during a defrost cycle while auxiliary heat fails.
Calculation: Calculate entering/leaving air delta T, runtime, capacity comparisons from supplied manufacturer data, and coefficient-of-performance awareness.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Hydronic systems, pumps, coils and distribution
Why it matters: A pump command or valve position does not prove water flow or heat transfer; temperature and pressure must be interpreted with mode and load.
Vocabulary and working scope
Closed/open loops; water/glycol; pump; head/pressure; flow; coil; control/isolation/balance valve; expansion; air separation; strainers; boilers/chillers; primary/secondary awareness.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A hot-water valve is open and pump proof is on, but supply/return temperatures show no heat transfer.
Calculation: Calculate water heat Q=500 x GPM x DeltaT for supplied assumptions, differential pressure, temperature drop, and flow/position plausibility.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Boilers, chillers, cooling towers and plant staging
Why it matters: Plant equipment has manufacturer and safety limits; BAS supervisory logic cannot replace listed safeties or qualified operation.
Vocabulary and working scope
Heating/cooling plants; enable; isolation; flow proof; entering/leaving temperatures; staging; lead/lag; minimum flow; reset; tower/fan; condenser/chilled/hot-water loops; safeties.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A second chiller stages while isolation is closed and flow proof is unreliable, causing a trip.
Calculation: Calculate plant delta T, approximate load from supplied flow, stage thresholds, runtime balance, efficiency metrics from supplied data, and recovery margin.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Terminal air delivery: VAV, VVT and measured-airflow hybrid VVT
Why it matters: Hybrid VVT can use standard VAV-capable controllers and crossflow pickup evidence, but remains a single central source whose mode and pressure strategy constrain zones.
Vocabulary and working scope
VAV airflow control; pressure-dependent VVT; central single-source heating/cooling; zone damper; bypass/relief; zone voting; Carrier VVT and Trane Vari-Trac concepts; measured-airflow hybrid; crossflow pickup; ventilation limits.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A perimeter zone calls for heat while the rooftop unit cools; its hybrid box controls airflow but cannot create local heating.
Calculation: Calculate airflow from supplied differential-pressure relationship, zone vote percentage, minimum/maximum airflow, diversity, and changed-mode behavior.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
VRF, split systems, DOAS and mixed-system buildings
Why it matters: VRF moves refrigerant to zones and may recover heat, but ventilation, exact operating limits, proprietary control, refrigerant safety, and gateway semantics require separate evidence.
Vocabulary and working scope
VRF heat pump/heat recovery; outdoor/indoor units; branch selector awareness; refrigerant zones; simultaneous heat/cool; ventilation via DOAS; condensate; gateway points; proprietary controls; lifecycle/safety.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A VRF zone is comfortable but CO2 rises because the associated DOAS is off; the gateway still reports indoor-unit fan operation.
Calculation: Calculate connected/diversified capacity from supplied data, ventilation deficit, runtime, gateway update age, and heat-recovery energy comparison.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
BAS points, sequences, trends and HVAC evidence; HVAC complaint diagnosis, restoration and professional explanation
Why it matters: BAS evidence is strongest when physical condition, signal, object, logic, command, proof, process response, time, and mode agree. A professional foundation avoids parts guessing: define normal, verify evidence, test one useful distinction, respect boundaries, and close every temporary state.
Vocabulary and working scope
AI/AO/BI/BO; enumerated/multistate; UI/UO; sensor/command/status/proof; setpoint; mode; sequence; alarm; trend; schedule; priority/override; timestamps; quality; graphic limitations. Complaint versus symptom; normal model; mode/load; evidence; hypotheses; discriminating test; trade boundary; escalation; temporary states; retest; restoration; documentation; defense.
Source-to-result trace
- Locate the controlling requirement and establish authority.
- Identify the physical and digital boundaries.
- Preserve as-found state and timestamps.
- Trace the initiating condition through logic, interfaces, equipment, and process response.
- Compare expected and actual evidence.
- Calculate with units and stated tolerance.
- Record action, result, restoration, uncertainty, and owner.
Worked thinking prompt
A cooling valve command rises with no position feedback, discharge temperature change, or trend-quality warning. Changed case: A cold-zone complaint includes a wrong schedule, stale space sensor, and partially closed damper; only one is the root cause in the current mode.
Calculation: Calculate command/proof error, response delay, trend sampling adequacy, percent outside limits, and point-evidence completeness. Rank hypotheses, calculate evidence coverage and timing, compare expected/actual values, and reconcile all observations and temporary states.
Retrieval prompts
- What would normal look like in this mode?
- Which two independent observations would strengthen the conclusion?
- What result would disprove the leading hypothesis?
- Which action requires authorization or a qualified person?
- What must be restored and documented?
Required and deeper reading
- Honeywell Engineering Manual of Automatic Control for Commercial Buildings
Foundational heat, HVAC process, control, devices, electricity, DDC, applications, and documentation; current standards and exact project/product information govern. - ASHRAE standards and guideline title/scope route
Use to locate current applicable standards; confirm edition, adoption, project, owner, and AHJ requirements. - U.S. Department of Energy VRF systems overview
Orientation to variable refrigerant flow heat-pump and heat-recovery system concepts; exact manufacturer design and service instructions govern. - KMC SSS crossflow airflow pickup tubes
Airflow pickup concept for measured-airflow terminal applications; exact product selection and installation instructions govern.