Ohio HVAC Contractor Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. What is the standard atmospheric pressure at sea level?
a) 10.7 psi
b) 12.7 psi
c) 14.7 psi
d) 16.7 psi
Rationale: Standard atmospheric pressure is 14.7 pounds per square
inch at sea level.
2. Which refrigerant is classified as having zero ozone depletion
potential?
a) R-22
b) R-12
c) R-410A
, d) R-500
Rationale: R-410A is an HFC with zero ozone depletion potential,
unlike R-22 or R-12 which contain chlorine.
3. The primary purpose of a TXV (thermostatic expansion valve) is to:
a) Regulate compressor speed
b) Control superheat
c) Regulate subcooling
d) Maintain system pressure
Rationale: The TXV maintains proper superheat at the evaporator
outlet to prevent liquid refrigerant from entering the compressor.
4. What type of current is supplied to most residential HVAC systems in
the United States?
a) 120V DC
b) 120/240V AC
c) 240V DC
d) 24V AC
Rationale: Residential systems are supplied by 120/240V alternating
current power.
5. Which device protects a compressor from damage caused by low
refrigerant charge?
a) High pressure switch
b) Contactor
c) Low pressure switch
, d) Crankcase heater
Rationale: A low pressure switch shuts off the compressor when
suction pressure drops too low, often indicating low refrigerant.
6. What does SEER stand for?
a) Seasonal Energy Equipment Rating
b) Seasonal Energy Efficiency Ratio
c) Standard Efficiency Energy Rating
d) Seasonal Electrical Energy Ratio
Rationale: SEER measures cooling efficiency of air conditioners and
heat pumps over a typical cooling season.
7. In duct design, what does friction rate represent?
a) Velocity of air in duct
b) Volume of airflow
c) Resistance to airflow per 100 feet of duct
d) Total static pressure
Rationale: Friction rate measures the pressure loss per 100 feet of
duct, key for sizing ducts properly.
8. Which safety control is used to prevent a furnace from overheating?
a) Gas pressure regulator
b) High limit switch
c) Pilot safety switch
d) Rollout switch
, Rationale: The high limit switch shuts down the furnace if it
overheats to prevent damage or fire.
9. What is the primary function of a heat anticipator in a thermostat?
a) Increase compressor run time
b) Prevent overshoot of temperature
c) Regulate fan delay
d) Maintain humidity
Rationale: The heat anticipator slightly warms the thermostat to
shut off heating early, preventing overshoot of set temperature.
10. Which of the following is a common type of refrigerant leak
detector?
a) Ultrasonic
b) Halide torch
c) Electronic sensor
d) All of the above
Rationale: Multiple leak detection methods exist including ultrasonic,
halide, and electronic sensors.
11. What is the most common duct material used in residential
HVAC?
a) Copper
b) Galvanized steel
c) Aluminum
Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. What is the standard atmospheric pressure at sea level?
a) 10.7 psi
b) 12.7 psi
c) 14.7 psi
d) 16.7 psi
Rationale: Standard atmospheric pressure is 14.7 pounds per square
inch at sea level.
2. Which refrigerant is classified as having zero ozone depletion
potential?
a) R-22
b) R-12
c) R-410A
, d) R-500
Rationale: R-410A is an HFC with zero ozone depletion potential,
unlike R-22 or R-12 which contain chlorine.
3. The primary purpose of a TXV (thermostatic expansion valve) is to:
a) Regulate compressor speed
b) Control superheat
c) Regulate subcooling
d) Maintain system pressure
Rationale: The TXV maintains proper superheat at the evaporator
outlet to prevent liquid refrigerant from entering the compressor.
4. What type of current is supplied to most residential HVAC systems in
the United States?
a) 120V DC
b) 120/240V AC
c) 240V DC
d) 24V AC
Rationale: Residential systems are supplied by 120/240V alternating
current power.
5. Which device protects a compressor from damage caused by low
refrigerant charge?
a) High pressure switch
b) Contactor
c) Low pressure switch
, d) Crankcase heater
Rationale: A low pressure switch shuts off the compressor when
suction pressure drops too low, often indicating low refrigerant.
6. What does SEER stand for?
a) Seasonal Energy Equipment Rating
b) Seasonal Energy Efficiency Ratio
c) Standard Efficiency Energy Rating
d) Seasonal Electrical Energy Ratio
Rationale: SEER measures cooling efficiency of air conditioners and
heat pumps over a typical cooling season.
7. In duct design, what does friction rate represent?
a) Velocity of air in duct
b) Volume of airflow
c) Resistance to airflow per 100 feet of duct
d) Total static pressure
Rationale: Friction rate measures the pressure loss per 100 feet of
duct, key for sizing ducts properly.
8. Which safety control is used to prevent a furnace from overheating?
a) Gas pressure regulator
b) High limit switch
c) Pilot safety switch
d) Rollout switch
, Rationale: The high limit switch shuts down the furnace if it
overheats to prevent damage or fire.
9. What is the primary function of a heat anticipator in a thermostat?
a) Increase compressor run time
b) Prevent overshoot of temperature
c) Regulate fan delay
d) Maintain humidity
Rationale: The heat anticipator slightly warms the thermostat to
shut off heating early, preventing overshoot of set temperature.
10. Which of the following is a common type of refrigerant leak
detector?
a) Ultrasonic
b) Halide torch
c) Electronic sensor
d) All of the above
Rationale: Multiple leak detection methods exist including ultrasonic,
halide, and electronic sensors.
11. What is the most common duct material used in residential
HVAC?
a) Copper
b) Galvanized steel
c) Aluminum
