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HVAC NEC 2023

HVAC Heat Pump Practice Test 2

Free HVAC Heat Pump Practice Test 2. 25 questions covering heat pump installation costs, air handler CFM calculations, low-voltage compressor effects, heating and cooling mode heat flow, indoor coil evaporator function, outdoor heat sink, frost efficiency reduction, defrost cycle timing, auxiliary heat in defrost, defrost thermostat location, dual fuel hybrid systems, outdoor unit clearances, condensate drain requirements, refrigerant overcharge and undercharge symptoms, HSPF heating efficiency rating, ECM blower motor advantages, MERV filter ratings, thermostat wiring terminals, lock-out tag-out safety procedures, capacitor functions, and heat pump noise troubleshooting.

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HVAC Practice tests

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Frequently Asked Questions

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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 concepts for this test: The CFM formula for air systems is CFM = BTU ÷ (1.08 × ΔT). A low supply voltage (below 90% of rated) causes compressor current to increase and can lead to overheating. During the defrost cycle, auxiliary heat strips energize to keep the indoor air warm while the heat pump temporarily switches to cooling to melt outdoor coil frost. The defrost thermostat is located at the bottom of the outdoor coil where ice first forms.

16

Questions

45 min

Time

70%

Pass

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HVAC Heat Pump Practice Test 2 — Question List

Question 1: The installation cost of heat pumps is more than electric resistance heaters.

True
False

Question 2: The return air temperature of a 120000 Btu output furnace is measured as 75<sup>0</sup>F and supply side air temperature is 55<sup>0</sup>F. What would be CFM of furnace?

5555
6755
5685
7125

Question 3: When 170 volts is supplied to 208/230 volts compressor ………..

It would cause current increase in the compressor
It would increase the resistance offered by the compressor
It would damage the compressor motor
It would cause power increase in the compressor

Question 4: In which of the following heat pump modes, the inside heat is moved to outside of the house?

Cooling mode
Deforest mode
Repair mode
Heating mode

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

Condensation
Evaporation
Compression
Expansion

Question 6: Which of the following is the heat sink in heat pump cooling cycle?

Air or water outside the structure
Air in the room
Ground and walls in the room

Question 7: 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 8: The time of defrost cycle depends on ………….

The amount of frost has collected on coil
The outdoor coil temperature
Outdoor Fan speed
All the options are correct

Question 9: In which of the following heat pump cycle, the auxiliary heating element will be operated?

Cooling cycle
Heating cycle
Defrost cycle

Question 10: <strong> </strong>Where does the defrost thermostat is located in heat pump?

Bottom of outdoor coil
Bottom of indoor coil
Above the outdoor coil
Above the indoor coil

Question 11: What is a dual fuel (hybrid) heat pump system and when does it switch from heat pump to gas furnace?

A dual fuel system uses two heat pumps (one for heating, one for cooling) for maximum efficiency
A dual fuel system pairs a heat pump with a gas furnace, switching to gas when outdoor temperatures fall below the economic balance point where gas becomes cheaper
A dual fuel system uses both electricity and propane simultaneously to power the heat pump compressor
A dual fuel system uses one refrigerant for cooling and a different refrigerant for heating mode

Question 12: What minimum clearances must be maintained around an outdoor heat pump unit, and why are they important?

No clearances are required — heat pump outdoor units can be installed flush against walls
Minimum 18-24 inch clearances on air inlet sides are required to prevent hot discharge air from recirculating back into the coil
Only the discharge side needs clearance — the air inlet sides can be within 6 inches of walls
Clearances are only required in cooling mode — in heating mode, units can be placed anywhere

Question 13: During heat pump cooling operation, the indoor coil produces condensate. What problems occur if the condensate drain becomes clogged?

A clogged condensate drain increases system efficiency by recycling moisture back into the airstream
A clogged drain causes drain pan overflow, potential structure damage, coil icing, and safety float switch shutdown
Condensate drains never clog because the water flow keeps them clear
A clogged drain only affects the cooling mode — heat pump heating is not impacted

Question 14: What is the function of a run capacitor on a heat pump compressor or fan motor?

The run capacitor stores excess electrical energy and releases it when demand peaks
The run capacitor creates a phase shift in motor winding current, allowing single-phase motors to develop a rotating magnetic field for continuous efficient operation
The run capacitor limits current flow to the motor during startup to prevent damage
The run capacitor provides backup power to the motor if the main power supply fails

Question 15: What does HSPF stand for and how is it used to compare heat pump heating efficiency?

HSPF = Heat System Power Factor; it measures the electrical power factor of the heat pump motor
HSPF = Heating Season Performance Factor; it measures total seasonal heating BTUs divided by total watt-hours — higher values indicate more efficient heating
HSPF = Heat Source Performance Frequency; it measures how often the heat pump cycles per hour in heating mode
HSPF = High-Speed Performance Factor; it only applies to variable-speed heat pump compressors

Question 16: What is an ECM blower motor and what advantages does it offer compared to a PSC (Permanent Split Capacitor) motor in a heat pump air handler?

ECM motors are only used in commercial systems — residential heat pumps always use PSC motors
ECM (Electronically Commutated Motor) is 2-3× more efficient than PSC, maintains constant airflow as filter loads, and offers variable speed for improved comfort and dehumidification
ECM motors use more energy than PSC motors but provide better control over airflow velocity
ECM motors are the same as PSC motors but with a different brand name

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

Questions16

Time limit45 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

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Source: NEC 2026 Art. 440 & electrical theory