Docsity
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Docsity AI
Docsity AI
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search for your university

Find the specific documents for your university's exams

Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

NEVADA C-21 HVAC CONTRACTOR EXAMINATION NEWEST 2025-2026 UPDATE REAL PRACTICE EXAM QUEST, Exams of Mechanical Engineering

Stanford UniversityMechanical Engineering

NEVADA C-21 HVAC CONTRACTOR EXAMINATION NEWEST 2025-2026 UPDATE REAL PRACTICE EXAM QUESTIONS & CORRECT ANSWERS | ALREADY GRADED A+

Typology: Exams

2025/2026

Available from 03/02/2026

eliteminds
eliteminds 🇺🇸

5

(1)

3.3K documents

1 / 27

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
NEVADA C-21 HVAC CONTRACTOR EXAMINATION
NEWEST 2025-2026 UPDATE REAL PRACTICE EXAM
QUESTIONS & CORRECT ANSWERS | ALREADY
GRADED A+
Content covered (most tested areas): refrigeration cycle, load
calculations, duct systems, electrical fundamentals, controls,
combustion, ventilation, codes, safety, installation standards,
troubleshooting, Nevada contracting practices
1. A refrigerant that boils at a low temperature under low pressure is
best described as having
A. high latent heat
B. low vapor pressure
C. low boiling point
D. high density
Answer: C. low boiling point
Refrigerants used in HVAC systems must vaporize at low
temperatures to absorb indoor heat effectively.
2. Superheat is defined as the temperature of vapor above its
A. freezing point
B. saturation temperature
C. condensing temperature
D. ambient temperature
Answer: B. saturation temperature
Superheat ensures no liquid refrigerant enters the compressor.
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14
pf15
pf16
pf17
pf18
pf19
pf1a
pf1b

Partial preview of the text

Download NEVADA C-21 HVAC CONTRACTOR EXAMINATION NEWEST 2025-2026 UPDATE REAL PRACTICE EXAM QUEST and more Exams Mechanical Engineering in PDF only on Docsity!

NEVADA C-21 HVAC CONTRACTOR EXAMINATION

NEWEST 2025-2026 UPDATE REAL PRACTICE EXAM

QUESTIONS & CORRECT ANSWERS | ALREADY

GRADED A+

Content covered (most tested areas): refrigeration cycle, load

calculations, duct systems, electrical fundamentals, controls,

combustion, ventilation, codes, safety, installation standards,

troubleshooting, Nevada contracting practices

  1. A refrigerant that boils at a low temperature under low pressure is best described as having A. high latent heat B. low vapor pressure C. low boiling point D. high density Answer: C. low boiling point Refrigerants used in HVAC systems must vaporize at low temperatures to absorb indoor heat effectively.
  2. Superheat is defined as the temperature of vapor above its A. freezing point B. saturation temperature C. condensing temperature D. ambient temperature Answer: B. saturation temperature Superheat ensures no liquid refrigerant enters the compressor.
  1. Subcooling occurs when liquid refrigerant is cooled below its A. boiling point B. ambient temperature C. saturation temperature D. discharge temperature Answer: C. saturation temperature Subcooling guarantees a solid column of liquid reaches the metering device.
  2. A thermostatic expansion valve responds primarily to A. head pressure B. evaporator pressure C. suction line temperature D. discharge temperature Answer: C. suction line temperature TXVs regulate refrigerant flow based on superheat sensed at the evaporator outlet.
  3. The component that removes heat from refrigerant vapor is the A. evaporator B. condenser C. accumulator D. receiver Answer: B. condenser The condenser rejects heat to the outdoor environment.
  4. Airflow across an evaporator coil that is too low will cause A. high suction pressure B. coil icing C. low superheat

B. phase shift control C. power supply circuit D. positive speed control Answer: A. permanent split capacitor PSC motors are common in fans and blowers.

  1. Static pressure in a duct system refers to A. air velocity pressure only B. pressure at the compressor C. resistance to airflow D. outdoor wind pressure Answer: C. resistance to airflow High static pressure indicates restrictions in ducts or filters.
  2. Return ducts should be sized to A. minimize airflow B. equal supply airflow C. increase noise D. eliminate filtration Answer: B. equal supply airflow Balanced airflow prevents pressure imbalances.
  3. The purpose of a plenum is to A. cool refrigerant B. distribute air C. increase voltage D. drain condensate Answer: B. distribute air Plenums serve as central air distribution chambers.
  1. A dirty air filter will most likely cause A. high airflow B. low static pressure C. reduced airflow D. higher voltage Answer: C. reduced airflow Blocked filters increase resistance and lower airflow.
  2. The refrigeration cycle begins at the A. condenser outlet B. evaporator outlet C. compressor inlet D. expansion device Answer: C. compressor inlet Cycle descriptions typically start with low-pressure vapor entering the compressor.
  3. Compressors are designed to compress A. liquid refrigerant B. oil only C. refrigerant vapor D. air Answer: C. refrigerant vapor Liquids can damage compressor valves.
  4. A capacitor’s function is to A. store electrical energy B. reduce airflow C. regulate refrigerant D. increase resistance

D. store energy Answer: B. switch high-voltage loads Thermostats control contactors to start compressors and fans.

  1. Low refrigerant charge typically results in A. high suction pressure B. low superheat C. low suction pressure D. high airflow Answer: C. low suction pressure Insufficient refrigerant reduces evaporator pressure.
  2. High head pressure can be caused by A. dirty condenser coil B. low airflow indoors C. low outdoor temperature D. oversized ducts Answer: A. dirty condenser coil Restricted heat rejection raises condensing pressure.
  3. The function of a reversing valve is to A. stop airflow B. reverse refrigerant flow C. regulate voltage D. drain condensate Answer: B. reverse refrigerant flow Allows heat pumps to switch between heating and cooling.
  4. A furnace heat exchanger transfers heat to A. refrigerant B. outdoor air

C. indoor air D. combustion gases Answer: C. indoor air Air passes over the exchanger to pick up heat.

  1. Proper combustion requires A. fuel only B. oxygen only C. fuel, oxygen, ignition D. electricity only Answer: C. fuel, oxygen, ignition These three elements form the combustion triangle.
  2. Carbon monoxide is dangerous because it is A. visible and heavy B. odorless and toxic C. lighter than air only D. nonreactive Answer: B. odorless and toxic CO binds to hemoglobin and prevents oxygen transport.
  3. Ventilation air is required to A. reduce humidity only B. supply oxygen and dilute contaminants C. cool refrigerant D. increase pressure Answer: B. supply oxygen and dilute contaminants Fresh air maintains indoor air quality.
  4. A condensate trap is needed to A. increase airflow
  1. A humidifier adds A. heat B. airflow C. moisture D. pressure Answer: C. moisture Used in dry climates to increase relative humidity.
  2. A dehumidifier removes A. oxygen B. heat only C. moisture D. refrigerant Answer: C. moisture Reduces indoor humidity levels.
  3. Refrigerant recovery is required to A. increase efficiency B. comply with environmental regulations C. reduce airflow D. improve combustion Answer: B. comply with environmental regulations Prevents release of ozone-depleting or greenhouse gases.
  4. A vacuum pump is used to A. add refrigerant B. remove moisture and air C. increase pressure D. test airflow

Answer: B. remove moisture and air Evacuation prevents contamination.

  1. Brazing differs from soldering because it uses A. lower temperatures B. higher temperatures C. no filler metal D. only aluminum Answer: B. higher temperatures Brazing creates stronger joints suitable for refrigeration piping.
  2. Nitrogen is used during brazing to A. cool the joint B. prevent oxidation inside tubing C. increase pressure D. test voltage Answer: B. prevent oxidation inside tubing Prevents scale formation that can clog components.
  3. A service disconnect must be located A. anywhere indoors B. within sight of equipment C. underground D. on the roof only Answer: B. within sight of equipment Allows safe servicing.
  4. Lockout/tagout procedures are intended to A. improve airflow B. prevent accidental energizing C. measure pressure

C. electrical current D. pressure only Answer: B. refrigerant condition Bubbles may indicate low charge.

  1. The primary heat transfer method in forced air systems is A. conduction B. radiation C. convection D. evaporation Answer: C. convection Moving air carries heat.
  2. Insulation on refrigerant lines prevents A. oil flow B. heat gain or loss C. pressure drop D. voltage loss Answer: B. heat gain or loss Maintains system efficiency and prevents condensation.
  3. A cracked heat exchanger can cause A. refrigerant leaks B. carbon monoxide infiltration C. high airflow D. low voltage Answer: B. carbon monoxide infiltration Combustion gases can mix with indoor air.
  4. Zoning systems use dampers to A. block refrigerant

B. control airflow to areas C. regulate voltage D. reduce pressure only Answer: B. control airflow to areas Allows independent temperature control.

  1. A programmable thermostat saves energy by A. increasing run time B. adjusting temperature schedules C. boosting voltage D. adding humidity Answer: B. adjusting temperature schedules Reduces conditioning when spaces are unoccupied.
  2. Preventive maintenance primarily aims to A. increase breakdowns B. extend equipment life C. reduce airflow D. raise energy use Answer: B. extend equipment life Regular service improves reliability and efficiency.
  3. An overcharged refrigeration system will most likely show A. low head pressure B. high head pressure C. low subcooling D. high superheat Answer: B. high head pressure

D. gas pressure Answer: B. insulation resistance Used to detect motor winding deterioration.

  1. Three-phase motors draw excessive current when A. voltage is balanced B. phase loss occurs C. temperature is low D. airflow is high Answer: B. phase loss occurs Single-phasing causes overheating and failure.
  2. Power factor measures A. airflow efficiency B. ratio of real power to apparent power C. refrigerant flow D. duct resistance Answer: B. ratio of real power to apparent power Low power factor indicates inefficient electrical usage.
  3. A relay coil is energized by A. mechanical force B. magnetic field from current C. refrigerant pressure D. airflow Answer: B. magnetic field from current Current flow creates a magnetic field that closes contacts.
  4. A transformer changes A. frequency B. voltage level

C. airflow D. pressure Answer: B. voltage level HVAC controls commonly use step-down transformers.

  1. The common control voltage in residential systems is A. 12 V B. 24 V C. 48 V D. 120 V Answer: B. 24 V Thermostats and relays typically operate at 24 volts.
  2. A float switch in a condensate pan is used to A. increase humidity B. shut system off if drain backs up C. regulate airflow D. measure temperature Answer: B. shut system off if drain backs up Prevents water damage from overflow.
  3. Air changes per hour measure A. refrigerant flow B. ventilation rate C. electrical load D. humidity only Answer: B. ventilation rate Indicates how often room air is replaced.
  4. Economizers are used to A. increase heating capacity
  1. High altitude installations require A. more fuel input B. derating of gas appliances C. larger ducts only D. lower airflow Answer: B. derating of gas appliances Reduced oxygen requires less fuel to maintain proper combustion.
  2. A thermocouple produces voltage when heated due to A. magnetic induction B. chemical reaction C. Seebeck effect D. capacitance Answer: C. Seebeck effect Heat generates a small electrical potential.
  3. A flame sensor verifies A. airflow B. refrigerant charge C. presence of flame D. gas pressure only Answer: C. presence of flame Ensures gas flow stops if ignition fails.
  4. Backdrafting occurs when A. flue gases spill into building B. airflow is excessive C. refrigerant leaks D. voltage drops

Answer: A. flue gases spill into building Often caused by negative indoor pressure.

  1. A hydronic system uses A. air as heat transfer medium B. water or fluid C. refrigerant only D. electricity only Answer: B. water or fluid Hydronics distribute heat via circulating liquid.
  2. Expansion tanks in hydronic systems accommodate A. refrigerant changes B. water expansion with temperature C. airflow increase D. pressure loss Answer: B. water expansion with temperature Prevents pressure buildup.
  3. A circulator pump moves A. air B. refrigerant C. water in hydronic loop D. combustion gases Answer: C. water in hydronic loop Ensures heat distribution through piping.
  4. Balancing valves are used to A. control voltage B. equalize flow in branches C. reduce humidity