HI HVAC study plan
HI HVAC · Give each week a clear focus.
8 weeks · About 7 hours per week
Heating Fundamentals and Equipment
Explain the combustion process for natural gas, propane, and oil, including the roles of primary and secondary air and the products of complete versus incomplete combustion
Calculate steady-state heat loss through walls, windows, and ceilings using U-values and design temperature difference, and compare it to equipment output
Distinguish AFUE, steady-state efficiency, and combustion efficiency, and state which one applies to a given rating scenario
Identify the major components and sequence of operation of a gas forced-air furnace from call for heat through blower off-delay
Your checkpoint
A one-page annotated furnace sequence-of-operation diagram plus a solved heat-loss worksheet for a single room showing U-value math and equipment sizing comparison
Heating Fundamentals and Equipment
Compare condensing and non-condensing furnaces, including flue gas dew point, condensate handling, and venting material restrictions
Describe hydronic boiler types (cast iron, condensing, combinational) and the function of expansion tanks, air elimination, and circulators
Diagnose common heating complaints such as short cycling, cold rooms far from the plenum, and rollout switch trips by listing probable causes in priority order
Set up and interpret combustion analyzer readings for O2, CO, CO2, and stack temperature
Your checkpoint
A troubleshooting matrix of at least 10 heating faults with probable cause, confirming test, and corrective action, each cross-checked against a manufacturer-style sequence of operation
Air Conditioning and Refrigeration Principles
Trace the vapor-compression cycle on a pressure-enthalpy diagram and label superheat, subcooling, and the four metering device states
Convert between gauge and absolute pressure, and between Fahrenheit and Celsius, without reference aids
Calculate superheat and subcooling from gauge and line temperatures for both fixed-orifice and TXV systems
Explain how evaporator and condenser airflow changes shift suction pressure, head pressure, superheat, and subcooling
Distinguish sensible heat ratio, latent capacity, and apparatus dew point in a cooling coil selection
Your checkpoint
A completed P-H diagram with the cycle plotted for one design condition, plus a table of eight airflow and charge fault scenarios predicting the direction of each key reading
Air Conditioning and Refrigeration Principles & Ductwork, Piping, and System Components
Identify refrigerant types by safety group and state the handling, recovery, and labeling rules that apply to each
Size and select refrigerant lines using velocity and pressure-drop limits, and explain why suction lines are insulated and sloped
Lay out a basic duct system using equivalent length and friction rate, and select fittings that minimize pressure loss
Describe the function and failure modes of TXVs, filter driers, accumulators, and crankcase heaters
Your checkpoint
A line-size and duct-layout package for one small system: selected suction and liquid line diameters with justification, plus a duct takeoff schedule with calculated total equivalent length
Ventilation and Indoor Air Quality
Apply ASHRAE 62.1 ventilation-rate procedure to compute outdoor air required for a given zone population and floor area
Explain how economizers, demand-controlled ventilation, and energy recovery ventilators interact with ventilation requirements
Identify the three main pollutant pathways in a building and the pressure-control strategy that stops each
Describe filtration ratings (MERV) and match filter selection to a stated IAQ or equipment-protection goal
Diagnose common IAQ complaints such as stuffiness, condensation on windows, and persistent odors by linking each to a measurable cause
Your checkpoint
A ventilation calculation sheet for a three-zone example showing required outdoor air, proposed system capacity, and a written recommendation for DCV or ERV with justification
Controls, Electrical, and Troubleshooting
Read a ladder diagram for a call for cooling and trace each safety and control in the circuit
Explain the role of thermostats, pressure switches, float switches, and high-limit controls in protecting equipment
Measure and interpret voltage, current, and resistance on a compressor circuit, including locked-rotor and running-load checks
Distinguish series and parallel circuit behavior when a switch or load opens, and predict the resulting meter readings
Describe how VAV boxes, economizer actuators, and building automation sequences respond to a zone demand
Your checkpoint
A hand-drawn ladder diagram of a cooling circuit annotated with expected voltage at each test point under normal, open-safety, and open-load conditions
Codes, Safety, and Load Calculations & Ductwork, Piping, and System Components
Perform a block and room load calculation using manual-style procedures, including orientation, internal gains, and infiltration
Apply code requirements for combustion air, clearances, condensate disposal, and refrigerant detection in occupied spaces
Identify the PPE, lockout/tagout, and refrigerant cylinder handling rules that apply to a service call
Verify duct static pressure and fan airflow against design, and state the correction needed when measured airflow is off
Your checkpoint
A load calculation summary for a two-room example with code compliance checklist and a written airflow correction plan based on measured static pressure
Heating Fundamentals and Equipment & Ventilation and Indoor Air Quality & Air Conditioning and Refrigeration Principles & Ductwork, Piping, and System Components & Controls, Electrical, and Troubleshooting & Codes, Safety, and Load Calculations
Answer timed practice sets across all six domains and log every miss by domain and root cause
Re-derive the five most error-prone formulas from memory: heat loss, superheat, subcooling, ventilation air, and airflow from static pressure
Rewrite weak-topic notes into one-page summaries that can be reviewed in under five minutes each
Simulate two full-length timed exams and analyze score trends by domain
Your checkpoint
A scored two-exam log with per-domain accuracy, a ranked list of the five weakest topics, and five one-page formula and concept summaries ready for final review
Milestones
Week 2: Score at least 80% on a 30-question self-made heating set, and correctly explain furnace sequence of operation aloud in under three minutes without notes
Week 4: Correctly predict the direction of suction pressure, head pressure, superheat, and subcooling for all eight fault scenarios in the week 3 deliverable, and pass a closed-book gauge-to-absolute and temperature conversion drill at 95%
Week 6: Trace a cooling ladder diagram cold and state expected meter readings at four test points with no errors, and score at least 75% on a mixed 40-question set spanning domains 1 through 5
Week 8: Achieve at least 80% overall on each of two full-length timed exams with no domain below 70%, and confirm the five weakest topics from week 8 have been rewritten and re-tested to at least 80%