HVAC Excellence Professional Technician (HEPT) Overview
These study notes are designed to prepare candidates for the HVAC Excellence Professional Technician (HEPT) exam. The HEPT exam assesses advanced knowledge in electrical diagnostics, refrigeration cycle analysis, heating systems, heat pumps, air distribution, and EPA compliance. Candidates should be familiar with ASHRAE handbooks, International Mechanical Code (IMC), International Energy Conservation Code (IECC), ACCA standards, and HVAC Excellence certification requirements. The practice baseline is 100 questions in 180 minutes with a 70% pass mark; verify official details with HVAC Excellence.
For Technical Conquer practice planning, this module is tracked as 100 questions over about 180 minutes with a listed pass mark of 70%. Treat those numbers as practice baselines and verify the current official format before scheduling.
How This Guide Is Organized
The sections below turn the syllabus into studyable subject blocks. Read a subject first, explain the must-know ideas without notes, then use questions, flashcards, and mind maps to test whether the knowledge holds under field-style pressure.
- Advanced Electrical Diagnostics and Control Logic
- Refrigeration Cycle Analysis and Component Performance
- Gas, Electric, and Hydronic Heating Systems
- Heat Pump Operation and Defrost Logic
- Air Distribution and Psychrometrics
- EPA Compliance and Refrigerant Management
Exam Snapshot and Readiness Target
Format: 100 questions, 180 minutes, 70% pass mark (practice baseline; verify official)
Candidate level: Experienced technician seeking professional-level certification
Readiness target: Demonstrate mastery in advanced diagnostics, system performance, and code compliance
Most candidates should budget at least 42+ focused study hours, then adjust upward for unfamiliar equipment, code, regulatory, commissioning, controls, or calculation-heavy content.
Advanced Electrical Diagnostics and Control Logic
Syllabus Focus
- Schematic reading and troubleshooting
- Motor and compressor starting circuits
- Control logic (relay, contactor, solid-state)
- Safety controls and interlocks
- Variable frequency drives (VFDs) and ECM motors
Key Notes
- Use a systematic approach: verify power, then control voltage, then component operation.
- Understand ladder diagrams: line voltage (L1, L2) and low-voltage (24V) circuits are separate.
- Common starting circuits: PSC (permanent split capacitor), CSR (capacitor start-run), and ECM (electronically commutated motor).
- Safety controls (high-pressure, low-pressure, freeze stats) are normally closed and wired in series.
- VFDs vary frequency to control motor speed; check for proper programming and parameter settings.
- Solid-state relays (SSRs) switch DC control signals to AC loads; test with a multimeter in diode mode.
Must Know
- How to read and interpret wiring diagrams for residential and commercial equipment.
- Troubleshooting sequence: check transformer output, then safety controls, then thermostat, then loads.
- Capacitor testing: use a microfarad setting; replace if capacitance is more than 10% below rating.
- Locked rotor amp (LRA) vs. running load amp (RLA): LRA is starting current; RLA is normal running current.
Field and Exam Application
- Diagnose a no-cool call: measure voltage at contactor coil; if 24V present but contactor not pulled in, check coil resistance.
- Use a clamp meter to measure compressor amperage; compare to RLA to detect mechanical issues.
- Program a VFD for a condenser fan: set minimum speed to avoid short cycling and maximum speed for design airflow.
High-Yield Distinctions
- PSC motors have a run capacitor only; CSR motors have both start and run capacitors with a potential relay.
- ECM motors have constant airflow or constant torque; troubleshoot with manufacturer-specific diagnostic tools.
- Contactor vs. relay: contactors handle higher current (usually >30A) and have arc suppression; relays are for lower current.
Common Pitfalls
- Assuming a capacitor is good because it looks fine; always test with a meter.
- Overlooking safety controls: a tripped high-pressure switch may indicate a condenser issue, not a control failure.
- Misinterpreting a 24V reading at the contactor coil as sufficient; check for voltage drop under load.
Review Tasks
- Practice tracing a ladder diagram from line voltage to load.
- Simulate a no-cool scenario and list all possible causes in order of likelihood.
- Calculate the expected capacitance for a 35 µF capacitor with ±5% tolerance.
Refrigeration Cycle Analysis and Component Performance
Syllabus Focus
- Pressure-enthalpy (P-h) diagrams
- Superheat and subcooling measurement
- Compressor performance and efficiency
- Expansion devices (TXV, EEV, capillary tube)
- System performance diagnostics
Key Notes
- Superheat = suction line temperature minus saturation temperature at evaporator pressure; target 8-12°F for TXV systems.
- Subcooling = saturation temperature at condenser pressure minus liquid line temperature; target 10-15°F for TXV systems.
- P-h diagram: plot high-side and low-side pressures, then calculate superheat and subcooling to assess system charge.
- TXV maintains constant superheat; EEV uses electronic control for precise metering; capillary tube is fixed and charge-sensitive.
- Compressor volumetric efficiency decreases with high compression ratio; check for high head pressure or low suction pressure.
Must Know
- How to measure and interpret superheat and subcooling for system diagnostics.
- Relationship between pressure and temperature for common refrigerants (R-410A, R-22, R-134a).
- Signs of undercharge: high superheat, low subcooling, low suction pressure, high discharge temperature.
- Signs of overcharge: low superheat, high subcooling, high head pressure, possible liquid slugging.
Field and Exam Application
- On a TXV system with 20°F superheat and 5°F subcooling, suspect undercharge or TXV starving.
- On a capillary tube system with 5°F superheat and 20°F subcooling, suspect overcharge.
- Use a P-h chart to determine if a compressor is operating within its design envelope.
High-Yield Distinctions
- TXV vs. capillary tube: TXV adjusts to load; capillary tube is fixed and relies on proper charge.
- Subcooling is more critical for TXV systems; superheat is more critical for capillary tube systems.
- EEV provides better efficiency than TXV in part-load conditions due to precise control.
Common Pitfalls
- Measuring superheat at the compressor instead of at the evaporator outlet; always measure at the service valve or sensing bulb location.
- Ignoring pressure drop in the suction line; use pressure at the evaporator outlet for saturation temperature.
- Assuming a TXV is bad without checking for a clogged inlet screen or incorrect bulb placement.
Review Tasks
- Calculate superheat and subcooling from given pressures and temperatures.
- Identify system charge condition from a set of readings (suction pressure, head pressure, line temperatures).
- Explain the effect of a dirty condenser on superheat and subcooling.
Gas, Electric, and Hydronic Heating Systems
Syllabus Focus
- Gas furnace operation and safety controls
- Electric heating elements and sequencers
- Hydronic system components (boilers, pumps, expansion tanks)
- Combustion analysis and efficiency
- Venting and combustion air requirements
Key Notes
- Gas furnaces: induced draft, hot surface igniter (HSI), flame sensor, pressure switch, gas valve.
- Electric furnaces: sequencers stage heating elements to prevent inrush current; check for open elements.
- Hydronic systems: circulator pump, expansion tank (diaphragm or bladder), air separator, pressure relief valve.
- Combustion efficiency = (100% - stack loss); measure O2, CO2, CO, and stack temperature.
- Venting: Category I (natural draft) requires proper draft; Category IV (condensing) uses PVC and requires condensate neutralization.
Must Know
- Gas furnace troubleshooting sequence: call for heat → inducer starts → pressure switch closes → igniter glows → gas valve opens → flame sensed.
- Electric furnace: check sequencer timing and continuity; measure voltage across elements.
- Hydronic system: verify expansion tank pre-charge matches system pressure; check for air in system.
- Combustion air: IMC requires two openings (one high, one low) for confined spaces; each at least 100 sq in per 100,000 Btu/h.
Field and Exam Application
- Diagnose a gas furnace that cycles on flame failure: check flame sensor for soot or weak microamp signal.
- For an electric furnace not heating, measure voltage at each element; if 240V present but no heat, element is open.
- In a hydronic system with noisy pipes, check for air by bleeding radiators and verifying expansion tank function.
High-Yield Distinctions
- Induced draft vs. natural draft: induced draft uses a fan to pull combustion gases; natural draft relies on buoyancy.
- Condensing vs. non-condensing: condensing furnaces have >90% AFUE and require PVC venting; non-condensing use metal flue.
- Hydronic vs. forced air: hydronic uses water as heat transfer medium; forced air uses air ducts.
Common Pitfalls
- Replacing a gas valve without checking for proper voltage and pressure switch operation.
- Oversizing a furnace leads to short cycling and reduced efficiency; perform Manual J load calculation.
- Ignoring condensate drain issues in high-efficiency furnaces; clogged drains cause pressure switch lockout.
Review Tasks
- List the sequence of operation for a typical 80% AFUE gas furnace.
- Calculate the required combustion air openings for a 120,000 Btu/h furnace in a confined space.
- Explain how to check a flame sensor with a microamp meter.
Heat Pump Operation and Defrost Logic
Syllabus Focus
- Reversing valve operation
- Defrost cycle initiation and termination
- Auxiliary and emergency heat
- Balance point and system sizing
- Refrigerant charge in heat pump mode
Key Notes
- Reversing valve: energized in cooling mode (some systems energized in heating; verify wiring).
- Defrost cycle: initiated by time/temperature or demand defrost (senses coil temperature and outdoor ambient).
- Defrost termination: typically when coil temperature reaches 50-60°F or after a maximum time (10-15 minutes).
- Auxiliary heat (electric strip) supplements when outdoor temperature drops below balance point.
- Emergency heat locks out compressor and uses only auxiliary heat; used when compressor fails.
Must Know
- How to test a reversing valve: check for voltage at solenoid; listen for gas flow change.
- Defrost board troubleshooting: check thermostat inputs, temperature sensors, and relay outputs.
- Balance point: outdoor temperature where heat pump capacity equals building load; typically 25-35°F.
- Refrigerant charge in heat pump: use subcooling method in cooling mode; in heating, use superheat method if no charging chart.
Field and Exam Application
- Heat pump in heating mode with no heat: check reversing valve for proper position; if stuck in cooling, coil may be cold.
- Frequent defrost cycles: check outdoor coil for dirt, low refrigerant, or faulty defrost sensor.
- Auxiliary heat running constantly: check balance point setting or thermostat staging.
High-Yield Distinctions
- Time/temperature defrost vs. demand defrost: demand defrost initiates only when needed, improving efficiency.
- Auxiliary heat vs. emergency heat: auxiliary operates with compressor; emergency heat bypasses compressor.
- Heat pump vs. air conditioner: heat pump has reversing valve and defrost control; AC does not.
Common Pitfalls
- Assuming a heat pump in defrost is malfunctioning; defrost is normal and lasts 5-15 minutes.
- Charging a heat pump in heating mode without a charging chart; use subcooling in cooling mode.
- Setting auxiliary heat to come on too early, reducing efficiency; balance point should be based on load calculation.
Review Tasks
- Describe the defrost cycle from initiation to termination.
- Explain how to determine the balance point for a given heat pump and building.
- List three causes of a reversing valve failing to shift.
Air Distribution and Psychrometrics
Syllabus Focus
- Psychrometric chart and processes
- Duct design (Manual D, static pressure)
- Airflow measurement (CFM, velocity)
- Fan laws and performance curves
- Indoor air quality (IAQ) and filtration
Key Notes
- Psychrometric chart: dry-bulb, wet-bulb, dew point, relative humidity, enthalpy, specific volume.
- Sensible heat ratio (SHR) = sensible heat / total heat; used to size cooling coils.
- Duct design: total external static pressure (TESP) should not exceed fan rating; typical residential TESP 0.5 in. w.c.
- Fan laws: CFM ∝ RPM, pressure ∝ RPM², power ∝ RPM³.
- Airflow measurement: traverse duct with pitot tube or use anemometer; calculate CFM = velocity × area.
Must Know
- How to read a psychrometric chart: locate dry-bulb and wet-bulb to find relative humidity and dew point.
- Manual D: duct sizing based on friction rate, velocity, and pressure drop.
- TESP measurement: measure static pressure at supply and return plenums; sum is TESP.
- MERV rating: higher MERV captures smaller particles but increases pressure drop.
Field and Exam Application
- Calculate CFM for a 12x12 duct with 800 fpm velocity: CFM = 800 × (12×12/144) = 800 × 1 = 800 CFM.
- Use psychrometric chart to determine if a cooling coil is dehumidifying properly: check leaving air dew point.
- Diagnose high static pressure: check for undersized ducts, dirty filters, or closed dampers.
High-Yield Distinctions
- Sensible vs. latent heat: sensible changes temperature; latent changes moisture content (humidity).
- Constant volume vs. VAV: constant volume delivers fixed CFM; VAV varies CFM to maintain temperature.
- Return air vs. fresh air: return air recirculates; fresh air is introduced for ventilation per IMC.
Common Pitfalls
- Using duct velocity alone to size ducts; must consider friction rate and pressure drop.
- Ignoring return air path: undersized return increases static pressure and reduces airflow.
- Assuming a psychrometric process is purely sensible; most cooling involves latent heat removal.
Review Tasks
- Plot a cooling process on a psychrometric chart: entering air 80°F DB, 67°F WB; leaving air 55°F DB, 54°F WB.
- Calculate TESP from given supply and return static pressures.
- Explain the impact of a dirty filter on system performance and energy use.
EPA Compliance and Refrigerant Management
Syllabus Focus
- Section 608 requirements
- Refrigerant recovery, recycling, and reclaiming
- Leak detection and repair
- Recordkeeping and reporting
- Refrigerant safety and handling
Key Notes
- EPA Section 608: technicians must be certified to buy and handle refrigerants; four types (Type I, II, III, Universal).
- Recovery: remove refrigerant from system without testing or processing; recycling: clean refrigerant for reuse; reclaim: process to AHRI 700 standard.
- Leak rate thresholds: commercial refrigeration (50% or more of charge) must be repaired when leak rate exceeds 35% annually; comfort cooling (50% or more) exceeds 15% annually.
- Recordkeeping: maintain records of refrigerant purchases, recovery, and leak repairs for 3 years.
- Refrigerant safety: use PPE, avoid contact with liquid (frostbite), ensure ventilation in confined spaces.
Must Know
- Required recovery equipment: recovery machine, recovery cylinder, hoses with low-loss fittings.
- Leak repair requirements: if leak rate exceeds threshold, repair must be completed within 30 days (or 120 days if retrofit/replacement plan).
- Ozone depletion potential (ODP) and global warming potential (GWP): R-22 ODP 0.05, GWP 1810; R-410A ODP 0, GWP 2088.
- Disposal: recover refrigerant before disposing of equipment; evacuate to 0 psig for small appliances (Type I).
Field and Exam Application
- During a system retrofit from R-22 to R-410A, recover R-22, replace expansion device, flush oil, and install new filter drier.
- For a supermarket rack with 500 lb R-404A, if annual leak is 200 lb (40%), repair is required within 30 days.
- Use a recovery machine to evacuate a residential AC to 500 microns before charging.
High-Yield Distinctions
- Type I (small appliances) vs. Type II (high-pressure) vs. Type III (low-pressure): different evacuation levels and equipment.
- Recovery vs. recycling: recovery removes refrigerant; recycling cleans it for reuse on same system.
- Leak rate calculation: (total refrigerant added in a year / full charge) × 100%.
Common Pitfalls
- Using a recovery cylinder for multiple refrigerants without proper labeling; cross-contamination is illegal.
- Not evacuating to required level: Type I requires 0 psig; Type II requires 0 psig for recovery but 500 microns for evacuation.
- Failing to report leaks to EPA if required; commercial systems with 50+ lb charge must report if leak rate exceeds threshold.
Review Tasks
- Calculate leak rate for a system with 100 lb charge that lost 20 lb in a year.
- List the steps for proper refrigerant recovery from a residential split system.
- Explain the difference between recycling and reclaiming refrigerant.
How To Use These Notes With Practice Questions
Do not jump straight from reading to a full mock. Work by subject first: review the key notes, make a short recall sheet from memory, then answer a focused question set. After each miss, decide whether the problem was missing theory, weak code/source recall, poor measurement setup, calculation error, or a field sequence you did not visualize.
Technical Conquer's question bank, flashcards, mind maps, and spaced review tools are most useful after this instruction layer because they reveal which parts of the notes are not yet retrievable.
Final Review Checklist
- Review all six subjects with emphasis on electrical diagnostics and refrigeration cycle analysis as they are foundational.
- Practice interpreting wiring diagrams and P-h charts under timed conditions.
- Memorize key code requirements from IMC and IECC for ventilation, combustion air, and duct design.
- Understand EPA Section 608 requirements thoroughly; leak rate calculations and repair timelines are common.
- Use the official sources (ASHRAE, IMC, ACCA) to verify any uncertain details; do not rely on third-party summaries alone.
- Take practice exams to identify weak areas and focus study time accordingly.
Official Sources and Further Reading
Use these sources as the final authority for format, eligibility, rules, regulatory limits, and exam updates. Study notes are a preparation layer, not a replacement for official candidate guidance.