Next HVAC Heat Pump Practice Test 2

HVAC NEC 2023

HVAC Heat Pump Practice Test 1

Free HVAC Heat Pump Practice Test 1. 25 questions covering heat pump efficiency advantages over electric resistance heaters, dirty air filter effects, refrigerant charging procedures, COP and BTU output per unit of electricity, indoor coil function in cooling cycle, frost effects on efficiency, defrost cycle operation, defrost termination temperature, electronic leak detector sensitivity, absolute pressure calculation, reversing valve operation, refrigerant types R-410A and R-22, TXV vs orifice metering devices, SEER and HSPF efficiency ratings, and heat pump system components.

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HVAC electrical exams cover electrical theory (Ohm's Law, circuits), transformers, single-phase and three-phase motors, control wiring, safety, and troubleshooting.

Requirements vary by state. HVAC technicians typically need EPA 608 certification and may need a separate electrical license for line voltage work.

Key facts for this test: Heat pumps are approximately four times more efficient than electric resistance heaters because they move heat rather than create it. The indoor coil acts as the evaporator during the cooling cycle, absorbing heat from indoor air. The defrost cycle reverses the heat pump to temporarily heat the outdoor coil and melt accumulated frost. Refrigerant charging is best performed in cooling mode because pressure-temperature relationships are more stable and predictable.

25

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45 min

Time

70%

Pass

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HVAC Heat Pump Practice Test 1 — Question List

Question 1: How many times the heat pumps are more efficient than electric resistance heaters in their user of electricity?

Two
Three
Four
Five

Question 2: The dirty and clogged air filter in a heat pump can cause:

Inadequate heating
Reduces the refrigerant pressure
Increases the refrigerant leak in the system
Increases the refrigerant pressure

Question 3: In a heat pump, which of the following mode is best to charge with refrigerant?

Heating mode
Cooling mode
Deforest mode
Repair mode

Question 4: For every unit of electricity the heat pumps are capable of producing ………… or more units of heat.

4 units
3 units
5 units
6 units

Question 5: In heat pump, what is the function of indoor coil in cooling cycle?

Condensation
Evaporation
Compression
Expansion

Question 6: When the frost is formed on the outdoor coil of heat pump:

The efficiency of the heat pump decreases
The efficiency of the heat pump increases
It will damage the outdoor coil
It will increase the air flow thus increases heat exchange.

Question 7: Which of the following action will be performed in defrost cycle of heat pump?

The frost on outdoor coil is removed by a component in heat pump
The heat pump cycle will be reversed at specific intervals to temporally heat the outdoor coil.
The heat pump will be stopped until the frost on outdoor coil is removed

Question 8: In heat pump defrost cycle, up to what temperature of outdoor coil the heat pump will remain cooling cycle?

67 <sup>0</sup> F
57 <sup>0</sup> F
87 <sup>0</sup> F
97 <sup>0</sup> F

Question 9: What is the smallest leak that an electronic leak detector is cable of sensing per year?

0.05 oz
0.5 oz
5 oz
0.005 oz

Question 10: At sea level if a gauge reads a pressure of 35 psig, what is its equivalent absolute pressure?

49.7 psia
26 psia
56.3 psia
45 psia

Question 11: What is the primary function of the reversing valve (4-way valve) in a heat pump system?

Regulates the refrigerant flow rate based on the indoor temperature demand
Changes the direction of refrigerant flow to allow operation in both heating and cooling modes
Controls the compressor speed to match the heating or cooling load
Prevents refrigerant from flowing backward through the compressor

Question 12: Which refrigerant replaced R-22 in new residential heat pump and air conditioning systems, and what is its key advantage?

R-134a replaced R-22 because it operates at lower pressure and is easier to handle
R-410A replaced R-22, offering zero ozone depletion potential and higher efficiency at approximately twice the operating pressure
R-404A replaced R-22 in residential systems because it has a lower global warming potential
R-12 replaced R-22 as it is a more stable CFC compound with better heat transfer properties

Question 13: What is the advantage of a thermostatic expansion valve (TXV) over a fixed orifice (cap tube or piston) metering device in a heat pump system?

A fixed orifice is more efficient because it has no moving parts that can fail
A TXV automatically maintains constant superheat by modulating flow to match varying load conditions
Both devices perform identically — the choice is based only on cost
A TXV is used only in heating mode while a fixed orifice is used only in cooling mode

Question 14: What does SEER stand for and what does it measure in a heat pump or air conditioning system?

SEER = Standard Equipment Efficiency Rating; it measures heating performance at a single temperature
SEER = Seasonal Energy Efficiency Ratio; it measures total cooling BTUs divided by total watt-hours consumed over a typical cooling season
SEER = Single Energy Efficiency Rating; it measures efficiency at exactly 95°F outdoor temperature
SEER = System Electrical Energy Rating; it measures how much electricity a system uses per hour of operation

Question 15: What is the "balance point" of a heat pump system?

The outdoor temperature at which the reversing valve switches the system from cooling to heating mode
The outdoor temperature at which the heat pump's heating output exactly equals the building's heat loss, below which auxiliary heat is required
The indoor temperature setpoint where the thermostat is set to maintain comfort
The operating pressure at which the compressor reaches maximum efficiency

Question 16: What is superheat in a refrigeration/heat pump system, and why is it important to measure?

The maximum temperature the refrigerant reaches inside the compressor during compression
The temperature of refrigerant vapor above its saturation temperature, measured at the suction line to confirm all liquid has evaporated
The temperature difference between the indoor and outdoor coils during normal operation
The amount of heat absorbed by the refrigerant during the compression process

Question 17: What is subcooling in a refrigeration/heat pump system and why does it matter for proper operation?

The process of cooling the refrigerant below the indoor setpoint temperature
The temperature of liquid refrigerant below its saturation temperature; it ensures liquid reaches the metering device without premature vaporization
The temperature drop across the evaporator coil during the cooling cycle
The amount of heat removed from the indoor air by the refrigerant during the cooling cycle

Question 18: What is the purpose of the crankcase heater on a heat pump or air conditioning compressor?

Heats the refrigerant to speed startup during cold winter mornings
Keeps the compressor oil warm during off cycles to prevent refrigerant migration and oil foaming on startup
Prevents the compressor from freezing when outdoor temperatures drop below 32°F
Maintains the lubricating oil at its optimum viscosity during normal operation

Question 19: What is the difference between "auxiliary heat" and "emergency heat" on a heat pump thermostat?

Emergency heat is more efficient than auxiliary heat and should be used whenever temperatures drop below 32°F
Auxiliary heat supplements the heat pump automatically; emergency heat bypasses the heat pump completely and should only be used when the heat pump has failed
Both terms describe the same function — the electric resistance strips that assist the heat pump in cold weather
Emergency heat uses a gas furnace backup while auxiliary heat uses electric resistance strips

Question 20: Why is cooling mode preferred for checking and adjusting refrigerant charge in a heat pump system?

Cooling mode uses less refrigerant so it is easier to add the correct amount
Cooling mode provides stable, well-established P-T relationships and allows use of standard superheat/subcooling charging charts
The compressor runs slower in cooling mode, making it safer to add refrigerant
Heating mode pressures are too high for manifold gauges to read accurately

Question 21: Which type of compressor is most commonly found in modern residential heat pump systems and what are its main advantages?

Reciprocating (piston) compressors are most common because they are the lowest cost option
Scroll compressors are most common in modern residential heat pumps due to higher efficiency, fewer moving parts, quieter operation, and better liquid tolerance
Centrifugal compressors are most common in residential heat pumps because they are the most efficient type available
Rotary compressors are the standard because they are the simplest design with the fewest parts

Question 22: Why are check valves used in a heat pump refrigerant circuit, and where are they typically located?

Check valves prevent the reversing valve from shifting until the compressor reaches operating speed
Check valves allow refrigerant to bypass expansion devices in one direction, ensuring each TXV only meters flow in the correct direction for each mode
Check valves prevent refrigerant from flowing back through the compressor when it cycles off
Check valves are only used in geothermal heat pump systems to direct flow through the ground loop

Question 23: A heat pump delivers 36,000 BTU/hr of heat to a building while consuming 4,000 watts of electricity. What is its Coefficient of Performance (COP)?

COP = 9.0
COP = 2.64
COP = 0.38
COP = 4.0

Question 24: What are the four essential components of the vapor-compression refrigeration cycle used in heat pump systems?

Compressor, filter, reversing valve, and condenser
Compressor, condenser, metering device (expansion valve), and evaporator
Compressor, heat exchanger, thermostat, and blower motor
Condenser, accumulator, expansion valve, and receiver

Question 25: What problem occurs when a heat pump operates in cooling mode at very low outdoor ambient temperatures, and how is this addressed?

Low outdoor temperatures cause the heat pump to overheat because there is too little heat to reject outdoors
Head pressure drops too low at cold outdoor temperatures in cooling mode; low ambient kits (fan cycling, flood-back) maintain adequate head pressure
The reversing valve cannot shift direction when outdoor temperature is below 50°F
Low ambient temperatures cause the refrigerant to freeze inside the outdoor coil, blocking flow

Key NEC References for This Test

Article	What It Covers
Art. 440	Air Conditioning Equipment — use nameplate MCA and MOCP, not FLA alone
Art. 430	Motors — general motor rules that Art. 440 modifies

Study Tip: Practice reading ladder diagrams. Trace each rung from L1 to the load: contacts open → circuit dead. Contacts closed → current flows. This is how HVAC electrical troubleshooting works.

EXAM CARD HVAC

Questions25

Time limit45 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

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Source: NEC 2026 Art. 440 & electrical theory