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HVAC NEC 2023

HVAC Heat Pump Practice Test 5

Free HVAC Heat Pump Practice Test 5. 25 questions on COP calculations, defrost thermostat positioning, auxiliary heat in defrost cycle, frost effect on efficiency, outdoor coil as condenser in cooling, heat direction in cooling mode, halogen leak detector sensitivity, voltage and current measurement, heat pump charging in cooling mode, unit capacity in 3+ ton heat pumps, zoning systems, mini-split ductless heat pumps, heat pump water heaters, geothermal basics, and heat pump installation codes.

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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: COP (Coefficient of Performance) = useful heat output ÷ energy input. A heat pump with COP of 3 delivers 3 BTUs of heat per BTU of electricity used. In cooling mode, heat moves from inside (indoor coil absorbs it) to outside (outdoor coil rejects it). The outdoor coil acts as the condenser in cooling mode — it rejects heat to the outdoor air. Review how mini-split (ductless) heat pumps differ from ducted systems for this test.

25

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45 min

Time

70%

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HVAC Heat Pump Practice Test 5 — Question List

Question 1: What is the highest possible COP number of heat pump?

1
2
3
4

Question 2: 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 3: In which of the following heat pump cycle, the auxiliary heating element will be operated?

Cooling cycle
Heating cycle
Defrost cycle

Question 4: 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 5: In heat pump, what is the function of outdoor coil in cooling cycle?

Condensation
Evaporation
Compression
Expansion

Question 6: 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 7: 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 8: 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 9: In a heat pump, which of the following mode is best to charge with refrigerant?

Heating mode
Cooling mode
Deforest mode
Repair mode

Question 10: 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 11: What is a zoning system in a ducted heat pump installation and what problem must be managed when zones close off?

Zoning systems reduce airflow to all areas equally when demand drops, causing no pressure issues
Zoning uses motorized dampers to control different areas; when zones close, static pressure rises — managed by bypass dampers or variable speed blowers to prevent coil freeze and compressor damage
Zoning is only used in commercial systems — residential heat pumps cannot support multiple zones
Closing zone dampers increases system efficiency because the heat pump only heats or cools the occupied areas

Question 12: What is a mini-split (ductless) heat pump and what are its advantages compared to a ducted central heat pump system?

Mini-split systems use very small ductwork (3-inch diameter) that fits inside walls instead of standard ductwork
Mini-split systems connect outdoor compressors to wall-mounted indoor units via small refrigerant lines with no ductwork, eliminating duct losses and enabling independent zone control at higher efficiency
Mini-split systems can only cool — they require separate heating equipment for winter operation
Mini-split systems are less efficient than ducted systems because the indoor coils are exposed to room air rather than enclosed in ducts

Question 13: How does a heat pump water heater (HPWH) work and what is its efficiency advantage over a conventional electric resistance water heater?

A heat pump water heater uses solar panels to convert sunlight directly into water heat
A heat pump water heater extracts heat from surrounding air using a refrigeration cycle, achieving COP of 2-3.5 compared to COP=1.0 for conventional resistance elements — saving 60-70% on water heating costs
Heat pump water heaters heat water faster than conventional units but use more electricity
A heat pump water heater is a standard electric water heater with an external heat pump added for cooling only

Question 14: In a ground source heat pump with a vertical closed loop, what is the typical depth of each borehole and what fluid circulates in the ground loop?

Vertical boreholes are 20-30 feet deep and use straight copper tubes filled with compressed air
Vertical boreholes are typically 150-400 feet deep; U-tube HDPE loops circulate a water-propylene glycol solution that exchanges heat with the stable ground temperature
Ground loop fluid is the same refrigerant used in the heat pump — R-410A circulates directly through the ground
Vertical boreholes must be drilled into bedrock — systems cannot work in soil

Question 15: When sizing a circuit breaker for a heat pump outdoor unit, what nameplate ratings must the electrician follow?

Use the compressor RLA × 1.5 to size both the wire and breaker — no other nameplate values are needed
NEC Article 440 requires conductors sized at or above the nameplate MCA and breakers that do not exceed the nameplate MOP
Any standard circuit breaker can be used — HACR ratings are a manufacturer recommendation, not a code requirement
The circuit breaker for a heat pump outdoor unit must always be sized exactly equal to the MCA value

Question 16: Why do heat pumps in hot-humid climates like Florida sometimes fail to adequately dehumidify even when cooling to setpoint temperature?

A heat pump that overshoots the setpoint temperature is removing too much humidity — reduce the refrigerant charge
Oversized heat pumps or short-cycling units fail to dehumidify because they satisfy the temperature setpoint before the coil is cold long enough to condense adequate moisture
Heat pumps in humid climates should have a higher thermostat setpoint to allow longer run cycles
Dehumidification is not affected by heat pump sizing — it depends only on outdoor humidity levels

Question 17: Why did R-22 refrigerant get phased out and what replaced it in residential heat pumps?

R-22 was phased out because it was less efficient than newer refrigerants, not for environmental reasons
R-22 was phased out under the Montreal Protocol due to its ozone depletion potential (ODP=0.05); R-410A (ODP=0) replaced it, and R-410A is now transitioning to lower-GWP alternatives like R-454B
R-22 phase-out only affects commercial equipment — residential heat pumps can still use new R-22
R-22 was replaced by R-134a, which has zero ODP and is compatible with R-22 oil

Question 18: What does the "A2L" refrigerant safety classification mean, and what special handling requirements does it impose?

A2L refrigerants are non-flammable and can be handled exactly like R-410A with standard tools
A2L refrigerants are mildly flammable (ASHRAE classification); service requires A2L-listed equipment, no open flames during service, A2L-rated leak detectors, and technician training on handling procedures
A2L is the same as A2 — both require explosion-proof tools and cannot be used in residential equipment
All next-generation refrigerants replacing R-410A are classified A3 (highly flammable) and require special refrigerant rooms

Question 19: A newly installed heat pump system has the thermostat set to HEAT but the system cools the house. What is the most likely cause?

If the heat pump cools when set to heat, add refrigerant to reverse the refrigerant flow direction
Most likely cause is incorrect O/B thermostat setting (O vs. B configuration) — the reversing valve is being energized in the wrong mode, reversing heating and cooling operation
If cooling occurs when set to heat, the reversing valve solenoid must be replaced immediately
The system heats and cools correctly — the thermostat labeling is backward from the factory

Question 20: What are the typical installation requirements for a mini-split indoor wall unit (head unit) regarding mounting height and clearances?

Mini-split indoor units should be mounted at eye level (5-6 feet) for easy access to the filter
Indoor units are typically mounted 7-8 feet high with 7-8 inches from the ceiling; the lineset hole through the wall should slope downward slightly toward the outside for condensate drainage
Mini-split indoor units can be mounted in any location because they use directional louvers to distribute air
The mounting height of mini-split indoor units does not affect performance — only the outdoor unit location matters

Question 21: Why does a heat pump's actual annual energy performance often differ significantly from its rated SEER and HSPF values?

SEER and HSPF ratings are always achieved in real-world operation — they are guaranteed by the manufacturer
Real-world performance differs from rated SEER/HSPF due to climate zone, duct losses, maintenance quality, equipment sizing, and thermostat management
SEER ratings apply only to commercial heat pumps — residential ratings use a different standard
Actual performance always exceeds the rated SEER because real-world conditions are better than laboratory test conditions

Question 22: Before opening an HFC heat pump system for repair, what EPA recovery level must be achieved and what happens if a technician intentionally vents refrigerant instead?

Technicians may vent small amounts of HFC refrigerant if the total quantity is less than 1 pound
HFC refrigerant must be recovered (not vented) before opening any system; intentional venting violates EPA Section 608 with civil penalties up to $44,539 per day per violation
Recovery is only required for HCFC refrigerants — HFCs like R-410A can be vented because they have zero ODP
Recovery is required only when more than 50 pounds of refrigerant is involved

Question 23: What technologies enable cold-climate heat pumps to maintain heating capacity at outdoor temperatures well below 0°F?

Cold climate heat pumps use propane as a supplemental fuel that is injected into the refrigerant circuit at low temperatures
Cold climate heat pumps use variable-speed inverter compressors, enhanced vapor injection (EVI), and larger coils to maintain useful heating capacity at -13°F or lower
Cold climate heat pumps are the same as standard heat pumps but with a thicker cabinet insulation to protect the compressor
Cold climate performance is achieved by pre-heating outdoor air with the auxiliary heat strips before it contacts the outdoor coil

Question 24: What is the recommended preventive maintenance schedule for a residential heat pump system to maintain warranty, efficiency, and reliability?

Heat pumps are self-maintaining — no scheduled service is needed for the first 10 years
Semi-annual maintenance (spring and fall) including filter replacement, coil cleaning, capacitor testing, refrigerant charge verification, electrical checks, and drain cleaning maintains efficiency and prevents failures
Only the air filter needs maintenance — all other heat pump components are sealed and maintenance-free
Maintenance should only be performed when a problem is noticed — preventive service has no proven benefit

Question 25: Why must R-410A refrigerant be charged as a liquid, and how is liquid charging accomplished while protecting the compressor?

R-410A can be charged as either liquid or vapor — both are equally acceptable
R-410A must be liquid-charged because it is a blend that fractionates if vapor-charged; liquid is slowly metered into the running low side so it vaporizes before reaching the compressor
R-410A is charged as vapor into the high side to avoid liquid entering the compressor
The charging method (liquid or vapor) depends only on outdoor temperature — use liquid above 90°F and vapor below 50°F

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

Timer starts immediately. Progress is auto-saved.

Source: NEC 2026 Art. 440 & electrical theory