CA C-20 HVAC Contractor Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf.
1. Which description most accurately defines the California C-20 Warm-
Air Heating, Ventilating and Air-Conditioning Contractor classification?
A. Installation of only refrigeration equipment used in industrial facilities
B. Installation of only electrical distribution equipment for HVAC systems
C. Fabrication, installation, maintenance, service, and repair of warm-air
heating, ventilating, and air-conditioning systems and associated ducts,
controls, registers, flues, and filters
D. Installation of structural plumbing systems exclusively
Rationale: The C-20 classification covers warm-air heating, ventilating, and
air-conditioning systems and associated components, including ducts,
registers, flues, humidity controls, thermostatic controls, and air filters.
2. Which component is specifically included within the C-20 scope when
associated with covered HVAC systems?
,A. Structural foundation reinforcement
B. Ducts, registers, flues, humidity controls, thermostatic controls, and air
filters
C. Domestic water distribution piping unrelated to HVAC
D. Structural steel framing
Rationale: The C-20 classification expressly encompasses the listed air-
distribution and control components when they are connected with
covered HVAC systems.
3. A contractor is installing a complete forced-air heating system in a
commercial building, including the furnace, ductwork, registers,
thermostatic controls, and filters. Which California classification most
directly applies?
A. C-12 Earthwork and Paving
B. C-36 Plumbing
C. C-20 Warm-Air Heating, Ventilating and Air-Conditioning
D. C-43 Sheet Metal
Rationale: A complete warm-air heating system and its associated ducts,
registers, thermostatic controls, and filters fall directly within the C-20
classification.
4. Which heat-pump work is specifically recognized within the C-20
classification?
,A. Only swimming-pool heat pumps
B. Only industrial refrigeration compressors
C. Water-heating heat pumps and HVAC system heat pumps within the C-
20 scope
D. Only automotive heat pumps
Rationale: California licensing guidance identifies C-20 as a classification
for HVAC system heat pumps and also recognizes water-heating heat
pumps within its scope.
5. What is the primary function of a thermostat in a conventional HVAC
system?
A. To increase refrigerant pressure
B. To sense or respond to space temperature and initiate or control
heating or cooling operation according to the system design
C. To filter combustion gases
D. To increase duct diameter
Rationale: A thermostat provides temperature-related control information
that allows the HVAC system to maintain the desired indoor conditions.
6. A thermostat is located in direct sunlight and consistently reads higher
than the actual room temperature. What is the most likely effect?
, A. The cooling system will always run continuously.
B. The thermostat may call for less heating or more cooling than is actually
required because its sensed temperature is inaccurate.
C. Refrigerant pressure will automatically increase.
D. Duct static pressure will become zero.
Rationale: Thermostat location affects temperature sensing, and direct
solar gain can produce an artificially high reading that causes incorrect
system control.
7. What is the primary purpose of a furnace heat exchanger?
A. To circulate refrigerant through the evaporator
B. To transfer heat from the combustion process or heat source to the air
stream while keeping combustion products separated from the
conditioned air
C. To increase duct friction
D. To filter return air
Rationale: The heat exchanger transfers useful heat into the air stream
while maintaining separation between combustion gases and indoor air.
8. Why is a cracked furnace heat exchanger a serious safety concern?
A. It increases filter efficiency.
B. It can allow combustion products, including potentially dangerous gases,
Questions And Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf.
1. Which description most accurately defines the California C-20 Warm-
Air Heating, Ventilating and Air-Conditioning Contractor classification?
A. Installation of only refrigeration equipment used in industrial facilities
B. Installation of only electrical distribution equipment for HVAC systems
C. Fabrication, installation, maintenance, service, and repair of warm-air
heating, ventilating, and air-conditioning systems and associated ducts,
controls, registers, flues, and filters
D. Installation of structural plumbing systems exclusively
Rationale: The C-20 classification covers warm-air heating, ventilating, and
air-conditioning systems and associated components, including ducts,
registers, flues, humidity controls, thermostatic controls, and air filters.
2. Which component is specifically included within the C-20 scope when
associated with covered HVAC systems?
,A. Structural foundation reinforcement
B. Ducts, registers, flues, humidity controls, thermostatic controls, and air
filters
C. Domestic water distribution piping unrelated to HVAC
D. Structural steel framing
Rationale: The C-20 classification expressly encompasses the listed air-
distribution and control components when they are connected with
covered HVAC systems.
3. A contractor is installing a complete forced-air heating system in a
commercial building, including the furnace, ductwork, registers,
thermostatic controls, and filters. Which California classification most
directly applies?
A. C-12 Earthwork and Paving
B. C-36 Plumbing
C. C-20 Warm-Air Heating, Ventilating and Air-Conditioning
D. C-43 Sheet Metal
Rationale: A complete warm-air heating system and its associated ducts,
registers, thermostatic controls, and filters fall directly within the C-20
classification.
4. Which heat-pump work is specifically recognized within the C-20
classification?
,A. Only swimming-pool heat pumps
B. Only industrial refrigeration compressors
C. Water-heating heat pumps and HVAC system heat pumps within the C-
20 scope
D. Only automotive heat pumps
Rationale: California licensing guidance identifies C-20 as a classification
for HVAC system heat pumps and also recognizes water-heating heat
pumps within its scope.
5. What is the primary function of a thermostat in a conventional HVAC
system?
A. To increase refrigerant pressure
B. To sense or respond to space temperature and initiate or control
heating or cooling operation according to the system design
C. To filter combustion gases
D. To increase duct diameter
Rationale: A thermostat provides temperature-related control information
that allows the HVAC system to maintain the desired indoor conditions.
6. A thermostat is located in direct sunlight and consistently reads higher
than the actual room temperature. What is the most likely effect?
, A. The cooling system will always run continuously.
B. The thermostat may call for less heating or more cooling than is actually
required because its sensed temperature is inaccurate.
C. Refrigerant pressure will automatically increase.
D. Duct static pressure will become zero.
Rationale: Thermostat location affects temperature sensing, and direct
solar gain can produce an artificially high reading that causes incorrect
system control.
7. What is the primary purpose of a furnace heat exchanger?
A. To circulate refrigerant through the evaporator
B. To transfer heat from the combustion process or heat source to the air
stream while keeping combustion products separated from the
conditioned air
C. To increase duct friction
D. To filter return air
Rationale: The heat exchanger transfers useful heat into the air stream
while maintaining separation between combustion gases and indoor air.
8. Why is a cracked furnace heat exchanger a serious safety concern?
A. It increases filter efficiency.
B. It can allow combustion products, including potentially dangerous gases,
