Technical Trade SchoolBAS-300 service-series
BAS-311
Concept reading and source route

BAS-311 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.

Module 1

Equipment identity and control-method overlays

Why it matters: The HVAC process is independent of whether the control signal is pneumatic, electric, electronic, or DDC; signal method changes the evidence path.

Vocabulary and working scope

System purpose; energy source/sink; components; airflow/water/refrigerant path; pneumatic/electric/electronic/DDC overlay; local versus BAS authority; factory controls; point identities.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

An older AHU uses pneumatic actuators with DDC EP transducers and a modern supervisor.

Calculation: Map percent command through 0–10 V or 4–20 mA to 3–15 psi and expected actuator direction using supplied ranges.

Retrieval prompts

Module 2

Terminal VAV, fan-powered, and fan-coil units

Why it matters: Airflow value is trustworthy only when pickup, tubing, sensor, range, K-factor, density basis, and calibration are correct.

Vocabulary and working scope

Pressure-dependent/independent; minimum/maximum; deadband; cooling; reheat; dual maximum; discharge limit; fan series/parallel; occupancy; flow pickup; K-factor; fail state.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A VAV box reports design airflow with the damper closed and AHU fan off.

Calculation: Use supplied flow=K×√ΔP relationship and min/max/dual-maximum sequence to predict state and airflow target.

Retrieval prompts

Module 3

VVT and hybrid measured-airflow VVT

Why it matters: Hybrid VVT can run on standard VAV controllers, but zone airflow measurement does not turn the central packaged source into a central VAV air handler.

Vocabulary and working scope

Single-source packaged heating/cooling; zone dampers; voting/priority; bypass/relief/static; changeover; airflow reference; standard VAV hardware; Honeywell Optimizer; ABB Cylon; Carrier/Trane concepts.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

Four zones vote for cooling while one perimeter zone needs heat and the bypass strategy is unstable.

Calculation: Calculate zone vote/priority, airflow target, crossflow pickup ΔP using supplied K, and central static/bypass response.

Retrieval prompts

Module 4

Packaged RTU, SZVAV, and heat-pump sequences

Why it matters: BAS commands are subordinate to factory safeties and OEM refrigerant/compressor controls.

Vocabulary and working scope

Enable; occupied fan; stages; economizer; compressor; gas/electric heat; reversing valve; defrost; low/high limits; demand; supply-air control; fan modes; safeties; lockout.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A heat pump enters defrost while the BAS trend appears to show simultaneous cooling and auxiliary heat.

Calculation: Calculate stage thresholds, delays, lockouts, supply-air targets, and expected mode from supplied sequence.

Retrieval prompts

Module 5

VAV air-handling systems

Why it matters: Static and SAT resets respond to verified demand within limits; they do not excuse failed boxes, sensors, or protections.

Vocabulary and working scope

Enable; fan/VFD/static; SAT; economizer; mechanical cooling; heating/preheat; freeze; minimum OA; relief/return; building pressure; resets; zone requests; failure/restart.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

Static pressure stays at maximum while many VAV dampers are nearly closed.

Calculation: Calculate mixed air, static/SAT reset, request response, fan speed estimates, and timing from the approved sequence.

Retrieval prompts

Module 6

Ventilation, DOAS, VRF, and heat-recovery interfaces

Why it matters: VRF does not inherently provide required outdoor air; the DOAS/ventilation path and controls must be identified separately.

Vocabulary and working scope

Outdoor air; exhaust; DOAS conditioning; dew point; heat recovery; VRF mode/branch selector; local OEM control; enable/status/alarm; ventilation ownership; zone coordination.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

VRF zones are comfortable while CO2 rises because the DOAS is disabled by schedule.

Calculation: Calculate ventilation path timing, dew-point target, heat-recovery temperature effectiveness when supplied, and mode demand.

Retrieval prompts

Module 7

Smoke, fire, and life-safety interface boundary

Why it matters: Ordinary HVAC optimization and operator commands never outrank approved smoke-control and fire-alarm functions.

Vocabulary and working scope

Fire alarm input; smoke-control mode awareness; fan/damper commands; proof; priority; firefighter control; normal HVAC inhibit; acceptance witness; restoration; no independent manipulation.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A normal occupied command conflicts with an active smoke-control mode indication.

Calculation: Build a priority/state table from supplied approved documents; do not calculate or invent life-safety acceptance criteria.

Retrieval prompts

Module 8

Boilers, hot-water plants, and heating distribution

Why it matters: Boiler availability and command do not prove flow, firing, heat transfer, or safe combustion.

Vocabulary and working scope

Enable; lead/lag; firing rate; supply reset; return-temperature protection; minimum flow; pumps; isolation; differential pressure; terminal demand; safeties; staging.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

Hot-water supply is below target while the lead boiler command is on and pump proof is questionable.

Calculation: Use Q=flow×ΔT×approved fluid factor, reset equations, staging thresholds, and minimum-flow criteria supplied.

Retrieval prompts

Module 9

Chillers, cooling towers, and chilled-water plants

Why it matters: Chiller command or run status does not prove correct water flow, capacity, efficiency, or tower operation.

Vocabulary and working scope

Enable; load; evaporator/condenser flow; isolation; lead/lag; staging; chilled-water reset; condenser-water reset; tower fans; minimum lift/flow; safeties; lockout.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

The chiller is at high load while chilled-water ΔT is low and bypass flow is suspected.

Calculation: Calculate tons or heat transfer from supplied flow/ΔT factors, staging load, approach, and plant reset targets.

Retrieval prompts

Module 10

Distribution, changeover, and cross-system optimization

Why it matters: Optimized requests and resets are applied only where the approved project sequence makes them applicable and all prerequisite evidence is trustworthy.

Vocabulary and working scope

Two-pipe/four-pipe; changeover; purge; isolation; simultaneous service; thermal storage awareness; district interface; requests; trim/respond; G36 applicability; fallback; interaction map.

Source-to-result trace

  1. Locate the controlling requirement and establish authority.
  2. Identify the physical and digital boundaries.
  3. Preserve as-found state and timestamps.
  4. Trace the initiating condition through logic, interfaces, equipment, and process response.
  5. Compare expected and actual evidence.
  6. Calculate with units and stated tolerance.
  7. Record action, result, restoration, uncertainty, and owner.

Worked thinking prompt

A two-pipe building changes to cooling while several heating valves remain open and zone requests persist.

Calculation: Calculate changeover conditions, required hold/purge time, request aggregation, reset limits, and energy-balance reasonableness.

Retrieval prompts

Required and deeper reading

Adoption note: Standards, codes, project requirements, owner criteria, manufacturer instructions, and employer safety programs control. Confirm the adopted edition and authority before applying a numeric requirement.