Florida Mechanical Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the minimum combustion air requirement for a gas-fired
appliance in a confined space?
A. 100 cubic feet per 1,000 BTU
B. 50 cubic feet per 1,000 BTU
C. 1 cubic foot per 1,000 BTU
D. 10 cubic feet per 1,000 BTU
Answer: C
Rationale: The Florida Mechanical Code requires 1 cubic foot of air
per 1,000 BTU of input for combustion appliances in confined spaces
to ensure safe operation.
2. What type of piping is most commonly used for hydronic heating
systems?
A. PVC
B. CPVC
C. PEX
D. ABS
Answer: C
Rationale: PEX piping is flexible, corrosion-resistant, and suitable for
hot water systems, making it standard for hydronic heating.
3. Which of the following is a primary purpose of a backflow preventer?
A. Increase water pressure
B. Filter sediment
C. Prevent contamination of potable water
D. Reduce flow velocity
, Answer: C
Rationale: Backflow preventers protect potable water from
contamination due to reverse flow from non-potable sources.
4. What is the maximum allowable spacing for supports of copper tubing
for water supply lines?
A. 4 feet
B. 6 feet
C. 8 feet
D. 10 feet
Answer: C
Rationale: The Florida Plumbing Code specifies copper tubing
supports at intervals no greater than 8 feet for horizontal runs.
5. What is the purpose of a relief valve on a water heater?
A. Increase heating efficiency
B. Reduce sediment buildup
C. Prevent excessive pressure buildup
D. Maintain temperature
Answer: C
Rationale: A relief valve protects the water heater from overpressure
conditions that could cause rupture or explosion.
6. Which type of mechanical system uses refrigerant to transfer heat?
A. Hydronic
B. Steam
C. HVAC (Vapor-compression system)
D. Geothermal ground loop
Answer: C
Rationale: HVAC systems using a vapor-compression cycle transfer
heat via refrigerants.
7. In a forced-air heating system, what component moves air through the
ducts?
A. Fan coil
B. Blower
C. Thermostat
D. Expansion tank
Answer: B
Rationale: The blower provides mechanical force to circulate heated
or cooled air through ductwork.
, 8. When installing a gas line, what is the maximum allowable leak rate for
a test?
A. 1 psi
B. 5 psi
C. 10 psi
D. 20 psi
Answer: C
Rationale: Gas lines are typically pressure-tested to 10 psi to ensure
no leaks before use.
9. What is the main function of an expansion tank in a closed-loop
hydronic system?
A. Heat water
B. Filter impurities
C. Absorb pressure changes
D. Provide backup water supply
Answer: C
Rationale: Expansion tanks prevent pressure surges in a closed-loop
system due to thermal expansion.
10. Which of the following is required on all gas-fired appliances
installed indoors?
A. Manual shutoff valve
B. Flexible connector
C. Vent for combustion gases
D. Pressure regulator
Answer: C
Rationale: Proper venting prevents dangerous accumulation of
combustion gases indoors.
11. What is the recommended slope for a horizontal drain pipe to
ensure proper drainage?
A. 1/16 inch per foot
B. 1/32 inch per foot
C. 1/4 inch per foot
D. 1/8 inch per foot
Answer: D
Rationale: Drain pipes must slope at 1/8 inch per foot to maintain
gravity flow and prevent standing water.
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the minimum combustion air requirement for a gas-fired
appliance in a confined space?
A. 100 cubic feet per 1,000 BTU
B. 50 cubic feet per 1,000 BTU
C. 1 cubic foot per 1,000 BTU
D. 10 cubic feet per 1,000 BTU
Answer: C
Rationale: The Florida Mechanical Code requires 1 cubic foot of air
per 1,000 BTU of input for combustion appliances in confined spaces
to ensure safe operation.
2. What type of piping is most commonly used for hydronic heating
systems?
A. PVC
B. CPVC
C. PEX
D. ABS
Answer: C
Rationale: PEX piping is flexible, corrosion-resistant, and suitable for
hot water systems, making it standard for hydronic heating.
3. Which of the following is a primary purpose of a backflow preventer?
A. Increase water pressure
B. Filter sediment
C. Prevent contamination of potable water
D. Reduce flow velocity
, Answer: C
Rationale: Backflow preventers protect potable water from
contamination due to reverse flow from non-potable sources.
4. What is the maximum allowable spacing for supports of copper tubing
for water supply lines?
A. 4 feet
B. 6 feet
C. 8 feet
D. 10 feet
Answer: C
Rationale: The Florida Plumbing Code specifies copper tubing
supports at intervals no greater than 8 feet for horizontal runs.
5. What is the purpose of a relief valve on a water heater?
A. Increase heating efficiency
B. Reduce sediment buildup
C. Prevent excessive pressure buildup
D. Maintain temperature
Answer: C
Rationale: A relief valve protects the water heater from overpressure
conditions that could cause rupture or explosion.
6. Which type of mechanical system uses refrigerant to transfer heat?
A. Hydronic
B. Steam
C. HVAC (Vapor-compression system)
D. Geothermal ground loop
Answer: C
Rationale: HVAC systems using a vapor-compression cycle transfer
heat via refrigerants.
7. In a forced-air heating system, what component moves air through the
ducts?
A. Fan coil
B. Blower
C. Thermostat
D. Expansion tank
Answer: B
Rationale: The blower provides mechanical force to circulate heated
or cooled air through ductwork.
, 8. When installing a gas line, what is the maximum allowable leak rate for
a test?
A. 1 psi
B. 5 psi
C. 10 psi
D. 20 psi
Answer: C
Rationale: Gas lines are typically pressure-tested to 10 psi to ensure
no leaks before use.
9. What is the main function of an expansion tank in a closed-loop
hydronic system?
A. Heat water
B. Filter impurities
C. Absorb pressure changes
D. Provide backup water supply
Answer: C
Rationale: Expansion tanks prevent pressure surges in a closed-loop
system due to thermal expansion.
10. Which of the following is required on all gas-fired appliances
installed indoors?
A. Manual shutoff valve
B. Flexible connector
C. Vent for combustion gases
D. Pressure regulator
Answer: C
Rationale: Proper venting prevents dangerous accumulation of
combustion gases indoors.
11. What is the recommended slope for a horizontal drain pipe to
ensure proper drainage?
A. 1/16 inch per foot
B. 1/32 inch per foot
C. 1/4 inch per foot
D. 1/8 inch per foot
Answer: D
Rationale: Drain pipes must slope at 1/8 inch per foot to maintain
gravity flow and prevent standing water.
