BPI AC and Heat Pump Professional (AC/HP) Overview
These study notes are designed to prepare candidates for the BPI AC and Heat Pump Professional certification exam. The content is anchored in official sources including ASHRAE handbooks, International Mechanical Code (IMC), International Energy Conservation Code (IECC), ACCA manuals, and BPI standards. The exam covers system selection, refrigeration cycle, airflow, electrical systems, installation, and diagnostics. Candidates should verify specific pass marks, eligibility, and other administrative details with BPI directly.
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.
- System Selection and Load Calculation
- Refrigeration Cycle and Thermodynamic Analysis
- Airflow Dynamics and Distribution Systems
- Electrical Systems and Control Logic
- Installation and Commissioning Standards
- Performance Diagnostics and Troubleshooting
Exam Snapshot and Readiness Target
Format: 100 questions, 180 minutes, pass mark 70% (practice baseline; verify with BPI)
Candidate level: Technician-level for service credentials
Readiness target: Demonstrate competence in residential AC and heat pump system design, installation, commissioning, and troubleshooting.
Most candidates should budget at least 42+ focused study hours, then adjust upward for unfamiliar equipment, code, regulatory, commissioning, controls, or calculation-heavy content.
System Selection and Load Calculation
Syllabus Focus
- Manual J load calculation
- Manual S equipment selection
- Manual D duct design
- Building envelope assessment
- Climate zone considerations
Key Notes
- Load calculations must follow ACCA Manual J or equivalent to determine heating and cooling loads based on building envelope, windows, insulation, infiltration, and internal gains.
- Equipment selection per ACCA Manual S ensures that the selected unit meets the calculated load without oversizing or undersizing; oversizing leads to short cycling and poor humidity control.
- Duct design per ACCA Manual D ensures proper airflow distribution; static pressure and friction loss calculations are critical.
- Building envelope assessment includes measuring insulation levels, window U-values, air leakage rates (using blower door), and duct leakage.
- Climate zone affects design conditions; use local outdoor design temperatures from ASHRAE Handbook or local codes.
Must Know
- Manual J: calculate sensible and latent loads, use correct indoor and outdoor design conditions.
- Manual S: match equipment capacity to load at design conditions, consider manufacturer's expanded ratings.
- Manual D: design duct system for total external static pressure within equipment limits.
- Understand the impact of infiltration and duct leakage on load calculations.
Field and Exam Application
- Perform a room-by-room load calculation for a 2,000 sq ft home using Manual J software.
- Select a heat pump that meets the heating and cooling loads with proper sizing for auxiliary heat.
- Design a duct system for a split system with a total external static pressure of 0.5 in w.c.
High-Yield Distinctions
- Sensible vs. latent load: sensible is dry-bulb temperature change, latent is moisture removal.
- Manual J vs. Manual S: load calculation vs. equipment selection.
- Oversizing vs. undersizing: oversizing causes short cycling and poor dehumidification; undersizing causes insufficient capacity.
- Design conditions: use 1% cooling and 99% heating outdoor design temperatures from ASHRAE.
Common Pitfalls
- Using rule-of-thumb sizing (e.g., 500 sq ft per ton) instead of Manual J.
- Ignoring duct leakage and infiltration in load calculations.
- Selecting equipment based on nominal tonnage without checking actual capacity at design conditions.
- Neglecting to account for internal heat gains from appliances and occupants.
Review Tasks
- Complete a Manual J load calculation for a sample home.
- Select a heat pump using Manual S for the calculated load.
- Calculate duct friction loss for a given duct layout.
- Review ASHRAE design conditions for your climate zone.
Refrigeration Cycle and Thermodynamic Analysis
Syllabus Focus
- Vapor-compression refrigeration cycle
- Pressure-enthalpy (P-h) diagrams
- Superheat and subcooling
- Refrigerant properties and types
- Heat pump cycle (reversing valve)
Key Notes
- The vapor-compression cycle consists of compression, condensation, expansion, and evaporation. In a heat pump, the reversing valve allows the cycle to reverse for heating mode.
- P-h diagrams are used to analyze cycle performance: locate evaporator and condenser pressures, calculate superheat (evaporator outlet temperature minus saturation temperature) and subcooling (condenser outlet saturation temperature minus liquid temperature).
- Superheat indicates proper refrigerant charge and evaporator performance; typical target superheat is 10-15°F for fixed orifice systems, 5-10°F for TXV systems.
- Subcooling indicates condenser performance and charge; typical target subcooling is 10-15°F for TXV systems.
- Refrigerant types: R-410A is common in newer systems; R-22 is being phased out. Understand pressure-temperature relationships and safety handling.
Must Know
- Read and interpret a P-h diagram for R-410A.
- Calculate superheat and subcooling from field measurements.
- Understand the function of the reversing valve in heat pump mode.
- Know the typical operating pressures for R-410A in cooling and heating modes.
Field and Exam Application
- Measure suction and liquid line pressures and temperatures to determine superheat and subcooling.
- Diagnose low charge: high superheat, low subcooling, low evaporator pressure.
- Diagnose overcharge: low superheat, high subcooling, high head pressure.
High-Yield Distinctions
- Superheat vs. subcooling: superheat is for evaporator, subcooling for condenser.
- Fixed orifice vs. TXV: fixed orifice has variable superheat; TXV maintains constant superheat.
- Cooling mode vs. heating mode: in heating, the outdoor coil becomes the evaporator and indoor coil the condenser.
- R-410A vs. R-22: R-410A operates at higher pressures (about 50% higher).
Common Pitfalls
- Confusing superheat and subcooling measurements.
- Using incorrect pressure-temperature chart for the refrigerant.
- Assuming TXV systems do not need subcooling check.
- Neglecting to account for line pressure drop when measuring pressures at the service valves.
Review Tasks
- Plot a refrigeration cycle on a P-h diagram for R-410A.
- Calculate superheat and subcooling from given pressures and temperatures.
- Identify symptoms of undercharge and overcharge.
- Explain the reversing valve operation.
Airflow Dynamics and Distribution Systems
Syllabus Focus
- CFM measurement and calculation
- Static pressure and total external static pressure (TESP)
- Duct design principles (Manual D)
- Air balancing and damper adjustment
- Fan laws and blower performance
Key Notes
- Airflow (CFM) is critical for system performance; typical requirement is 400 CFM per ton for cooling, 350-400 CFM per ton for heat pump heating.
- Total external static pressure (TESP) is the sum of supply and return static pressures measured at the equipment; must be within manufacturer's limits (usually 0.5-0.8 in w.c.).
- Duct design per Manual D uses friction loss charts and equivalent lengths to size ducts; avoid high velocity and excessive turns.
- Air balancing involves adjusting dampers to achieve design CFM to each room; use flow hood or pitot tube traverse.
- Fan laws: CFM varies directly with fan speed, pressure varies with square of speed, power varies with cube of speed.
Must Know
- Measure TESP using a manometer at the supply and return plenums.
- Calculate CFM from static pressure using manufacturer's fan performance data.
- Identify duct sizing errors: undersized ducts cause high static pressure and low airflow.
- Understand the impact of dirty filters, coils, and blower wheels on airflow.
Field and Exam Application
- Measure TESP on a 3-ton heat pump and compare to manufacturer's allowable range.
- Use a flow hood to measure supply register CFM and balance system.
- Calculate required duct size for a 100 ft run with 0.1 in w.c./100 ft friction loss.
High-Yield Distinctions
- Supply vs. return static pressure: both must be measured; return restrictions are common.
- Static pressure vs. velocity pressure: static is potential energy, velocity is kinetic.
- Manual D vs. Manual J: duct design vs. load calculation.
- Fan laws: speed change affects CFM linearly, but power cubically.
Common Pitfalls
- Measuring static pressure at the wrong location (e.g., after filters or coils).
- Assuming airflow is correct without measurement.
- Oversizing ducts reduces velocity but may not fit; undersizing increases noise and pressure.
- Ignoring duct leakage: leaky ducts reduce delivered airflow and increase energy loss.
Review Tasks
- Measure TESP on a system and calculate CFM from fan curve.
- Perform a duct traverse to measure airflow in a main trunk.
- Balance a system by adjusting dampers to achieve design CFM.
- Review Manual D friction loss charts.
Electrical Systems and Control Logic
Syllabus Focus
- Electrical fundamentals (voltage, current, resistance, power)
- Wiring diagrams and schematics
- Thermostats and control wiring
- Capacitors, contactors, relays, and transformers
- Safety devices: fuses, breakers, high-pressure switches, low-pressure switches
Key Notes
- Understand Ohm's law (V=IR) and power formula (P=VI). Single-phase residential systems: 240V for compressor, 120V for blower and controls.
- Wiring diagrams: line diagrams show power flow; schematic diagrams show control logic. Identify common components: compressor, fan motor, capacitor, contactor, transformer, thermostat.
- Thermostat wiring: R (24V hot), C (common), Y (cooling), W (heating), G (fan), O/B (reversing valve). Heat pumps may use O for cooling or B for heating.
- Capacitors: start capacitors provide high torque; run capacitors improve efficiency. Measure capacitance with a meter; replace with same microfarad rating.
- Safety devices: high-pressure switch opens on excessive head pressure; low-pressure switch opens on low suction pressure (loss of charge).
Must Know
- Read a schematic diagram and trace the control circuit.
- Test a capacitor for proper capacitance and discharge safely.
- Identify thermostat wiring errors: missing C wire causes power issues.
- Understand the function of a contactor and how to test it.
Field and Exam Application
- Troubleshoot a no-cooling call: check thermostat, transformer, contactor, capacitor, and safety switches.
- Replace a run capacitor on a compressor motor.
- Wire a heat pump thermostat with auxiliary heat.
High-Yield Distinctions
- Start vs. run capacitors: start capacitors are in series with start winding and have a relay; run capacitors are in parallel with start winding.
- Potential relay vs. current relay: potential relay opens on back EMF; current relay opens on high current.
- Single-phase vs. three-phase: residential is single-phase; commercial may be three-phase.
- Low-voltage (24V) vs. line-voltage (120/240V) circuits: safety precautions differ.
Common Pitfalls
- Discharging capacitors improperly (risk of shock).
- Miswiring thermostat: O/B terminal confusion.
- Replacing a capacitor with wrong microfarad or voltage rating.
- Ignoring safety switches: bypassing them can cause compressor damage.
Review Tasks
- Draw a basic control circuit for a heat pump.
- Practice reading a wiring diagram from a manufacturer.
- Test a capacitor with a multimeter.
- Identify thermostat terminals and their functions.
Installation and Commissioning Standards
Syllabus Focus
- Refrigerant piping and line sizing
- Electrical connections and disconnects
- Condensate drainage
- Commissioning procedures (startup, charge verification, airflow measurement)
- Code compliance (IMC, IECC, local codes)
Key Notes
- Refrigerant line sizing: follow manufacturer guidelines for line length, diameter, and insulation. Long lines require oil traps and proper slope.
- Electrical: install disconnect within sight of equipment, use proper wire gauge, and ensure grounding. Follow NEC and local codes.
- Condensate drainage: slope drain line at least 1/4 inch per foot, install trap, and terminate to an approved location. IMC requires condensate drains to be trapped and vented.
- Commissioning: verify refrigerant charge using subcooling (TXV) or superheat (fixed orifice), measure airflow, check temperature split, and verify safety controls.
- Code compliance: IMC covers mechanical systems; IECC covers energy efficiency (e.g., minimum SEER2, duct insulation).
Must Know
- Proper refrigerant line installation: avoid kinks, use brazing with nitrogen purge.
- Commissioning steps: check voltage and amperage, measure pressures and temperatures, calculate superheat/subcooling, measure airflow, verify delta T.
- Condensate drain requirements: trap, slope, and termination per IMC.
- Energy code requirements: duct insulation R-value, equipment efficiency minimums.
Field and Exam Application
- Install a 3-ton heat pump with 50 ft line set: select line sizes and add oil trap if needed.
- Commission a new system: record pressures, temperatures, superheat, subcooling, and airflow.
- Inspect condensate drain for proper trap and slope.
High-Yield Distinctions
- Brazing vs. soldering: brazing with sil-phos requires nitrogen to prevent oxidation.
- Line set insulation: suction line must be insulated; liquid line may be insulated in hot climates.
- TXV vs. fixed orifice charging: TXV uses subcooling; fixed orifice uses superheat.
- Delta T: typical 15-20°F in cooling mode; 10-15°F in heating mode (depending on conditions).
Common Pitfalls
- Not using nitrogen purge during brazing (causes copper oxide contamination).
- Oversizing or undersizing refrigerant lines.
- Improper condensate drain installation (no trap, no slope).
- Skipping commissioning steps: assuming charge is correct without measurement.
Review Tasks
- Practice brazing with nitrogen purge.
- Perform a full commissioning on a heat pump system.
- Review IMC condensate drain requirements.
- Check local energy code for duct insulation requirements.
Performance Diagnostics and Troubleshooting
Syllabus Focus
- System performance metrics (SEER2, HSPF2, COP, EER)
- Diagnostic tools (manometer, thermometer, clamp meter, refrigerant scale)
- Common faults: refrigerant leaks, compressor failure, airflow restrictions, electrical faults
- Heat pump specific: defrost cycle, auxiliary heat operation, reversing valve issues
- Safety and health: carbon monoxide, combustion safety, refrigerant handling
Key Notes
- SEER2 and HSPF2 are seasonal efficiency ratings; higher is better. COP is coefficient of performance (heating output divided by electric input).
- Diagnostic tools: manometer for static pressure, thermometer for temperature split, clamp meter for amperage, refrigerant scale for charge verification.
- Common faults: low charge (high superheat, low subcooling, low suction pressure), overcharge (low superheat, high subcooling, high head pressure), compressor short cycling (electrical or thermal overload).
- Heat pump defrost: initiated by temperature sensor or timer; auxiliary heat (electric strip) supplements during defrost and low outdoor temperatures.
- Safety: check for carbon monoxide from combustion appliances; handle refrigerant with PPE and recovery equipment per EPA regulations.
Must Know
- Interpret system pressures and temperatures to diagnose refrigerant issues.
- Identify defrost cycle operation: outdoor fan stops, reversing valve switches to cooling, auxiliary heat energizes.
- Measure and calculate COP from electrical and thermal data.
- Understand the importance of proper refrigerant recovery and handling.
Field and Exam Application
- Diagnose a system with high head pressure and low suction: possible restriction or overcharge.
- Troubleshoot a heat pump that is not heating: check reversing valve, auxiliary heat, defrost board.
- Perform a combustion safety test on a gas furnace (if combined system).
High-Yield Distinctions
- SEER2 vs. SEER: SEER2 uses a different test procedure (M1 blower); SEER2 is typically lower.
- HSPF2 vs. HSPF: similar change; HSPF2 is the current metric.
- Defrost cycle: cooling mode during defrost causes cold air if auxiliary heat fails.
- Auxiliary heat: should only operate when needed; excessive use indicates heat pump sizing issue.
Common Pitfalls
- Misdiagnosing a TXV failure as a refrigerant leak.
- Ignoring airflow issues when diagnosing performance.
- Not checking defrost cycle operation in heating season.
- Improper refrigerant recovery: venting is illegal and harmful.
Review Tasks
- Use a diagnostic chart to identify common faults from pressure readings.
- Simulate a defrost cycle and observe operation.
- Calculate COP from measured power and heat output.
- Review EPA Section 608 requirements for refrigerant handling.
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 Manual J, S, D fundamentals and practice calculations.
- Master P-h diagram interpretation and superheat/subcooling calculations.
- Practice measuring TESP and airflow; understand fan curves.
- Study electrical schematics and component testing procedures.
- Know commissioning steps and code requirements (IMC, IECC).
- Develop diagnostic reasoning for common system faults.
- Review heat pump specific cycles: defrost, reversing valve, auxiliary heat.
- Ensure familiarity with safety protocols: refrigerant handling, electrical safety, carbon monoxide testing.
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.