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MASTER MECHANICAL – G29-N CONTRACTOR Exam 2026-
2027 BANK QUESTIONS WITH DETAILED VERIFIED
ANSWERS EXAM QUESTIONS WILL COME FROM HERE
(100% Latest Already Graded A+
QUESTION 1
In a vapor compression refrigeration cycle, the condition of the
refrigerant entering the compressor is best described as:
A) High-pressure superheated vapor
B) Low-pressure superheated vapor
C) High-pressure saturated liquid
D) Low-pressure saturated liquid
Answer: B) Low-pressure superheated vapor
Explanation: The refrigerant enters the compressor as a low-pressure
superheated vapor. This ensures that no liquid droplets enter the
compressor, which would cause slugging and mechanical damage. The
superheat provides a safety margin and improves volumetric efficiency.
QUESTION 2
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A centrifugal pump is operating against a total dynamic head of 120
feet and delivers 800 gallons per minute. Calculate the water
horsepower if the pump efficiency is 85 percent.
A) 18.2 HP
B) 24.2 HP
C) 28.5 HP
D) 32.4 HP
Answer: B) 24.2 HP
Explanation: Water horsepower = (Flow rate in GPM × Total Dynamic
Head in feet) / 3960. WHP = (800 × 120) / 3960 = 24.24 HP. Brake
horsepower = WHP / Efficiency = 24..85 = 28.5 HP. The question
asks for water horsepower, which is 24.2 HP.
QUESTION 3
The primary purpose of an expansion tank in a closed-loop hydronic
heating system is to:
A) Increase system pressure
B) Provide a reservoir for system water
C) Accommodate thermal expansion of water
D) Remove air from the system
Answer: C) Accommodate thermal expansion of water
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Explanation: As water is heated in a closed hydronic system, it expands
significantly. The expansion tank provides a compressible air cushion or
diaphragm chamber to absorb this increased volume, preventing
excessive system pressure that could cause relief valve operation or pipe
damage.
QUESTION 4
According to the Mechanical Code, what is the minimum clearance
required in front of a commercial boiler for service access?
A) 18 inches
B) 24 inches
C) 30 inches
D) 36 inches
Answer: C) 30 inches
Explanation: Most mechanical codes require a minimum working
clearance of 30 inches in front of boilers and major mechanical
equipment for safe access during maintenance and repair operations.
This clearance must be unobstructed and extend the full width of the
equipment.
QUESTION 5
In parallel pipe systems, the total flow rate is equal to:
A) The sum of the flow rates in each branch
B) The average of the flow rates in each branch
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C) The flow rate in the largest branch
D) The difference between the largest and smallest branch flows
Answer: A) The sum of the flow rates in each branch
Explanation: In a parallel piping configuration, the continuity equation
requires that the total flow entering the system equals the sum of the
flows through each parallel branch. The pressure drop across each
branch is identical, but the flow distribution depends on individual
branch characteristics.
QUESTION 6
A thermostatic expansion valve (TXV) responds to which two
parameters to control refrigerant flow?
A) Evaporator pressure and compressor suction temperature
B) Evaporator outlet temperature and pressure
C) Bulb temperature and evaporator pressure
D) Condenser pressure and liquid line temperature
Answer: C) Bulb temperature and evaporator pressure
Explanation: The TXV uses a sensing bulb attached to the suction line to
measure temperature (which corresponds to superheat) and an external
equalizer line to sense evaporator pressure. The valve modulates flow to
maintain a constant superheat at the evaporator outlet by balancing
these two opposing forces.
MASTER MECHANICAL – G29-N CONTRACTOR Exam 2026-
2027 BANK QUESTIONS WITH DETAILED VERIFIED
ANSWERS EXAM QUESTIONS WILL COME FROM HERE
(100% Latest Already Graded A+
QUESTION 1
In a vapor compression refrigeration cycle, the condition of the
refrigerant entering the compressor is best described as:
A) High-pressure superheated vapor
B) Low-pressure superheated vapor
C) High-pressure saturated liquid
D) Low-pressure saturated liquid
Answer: B) Low-pressure superheated vapor
Explanation: The refrigerant enters the compressor as a low-pressure
superheated vapor. This ensures that no liquid droplets enter the
compressor, which would cause slugging and mechanical damage. The
superheat provides a safety margin and improves volumetric efficiency.
QUESTION 2
,2|Page
A centrifugal pump is operating against a total dynamic head of 120
feet and delivers 800 gallons per minute. Calculate the water
horsepower if the pump efficiency is 85 percent.
A) 18.2 HP
B) 24.2 HP
C) 28.5 HP
D) 32.4 HP
Answer: B) 24.2 HP
Explanation: Water horsepower = (Flow rate in GPM × Total Dynamic
Head in feet) / 3960. WHP = (800 × 120) / 3960 = 24.24 HP. Brake
horsepower = WHP / Efficiency = 24..85 = 28.5 HP. The question
asks for water horsepower, which is 24.2 HP.
QUESTION 3
The primary purpose of an expansion tank in a closed-loop hydronic
heating system is to:
A) Increase system pressure
B) Provide a reservoir for system water
C) Accommodate thermal expansion of water
D) Remove air from the system
Answer: C) Accommodate thermal expansion of water
,3|Page
Explanation: As water is heated in a closed hydronic system, it expands
significantly. The expansion tank provides a compressible air cushion or
diaphragm chamber to absorb this increased volume, preventing
excessive system pressure that could cause relief valve operation or pipe
damage.
QUESTION 4
According to the Mechanical Code, what is the minimum clearance
required in front of a commercial boiler for service access?
A) 18 inches
B) 24 inches
C) 30 inches
D) 36 inches
Answer: C) 30 inches
Explanation: Most mechanical codes require a minimum working
clearance of 30 inches in front of boilers and major mechanical
equipment for safe access during maintenance and repair operations.
This clearance must be unobstructed and extend the full width of the
equipment.
QUESTION 5
In parallel pipe systems, the total flow rate is equal to:
A) The sum of the flow rates in each branch
B) The average of the flow rates in each branch
, 4|Page
C) The flow rate in the largest branch
D) The difference between the largest and smallest branch flows
Answer: A) The sum of the flow rates in each branch
Explanation: In a parallel piping configuration, the continuity equation
requires that the total flow entering the system equals the sum of the
flows through each parallel branch. The pressure drop across each
branch is identical, but the flow distribution depends on individual
branch characteristics.
QUESTION 6
A thermostatic expansion valve (TXV) responds to which two
parameters to control refrigerant flow?
A) Evaporator pressure and compressor suction temperature
B) Evaporator outlet temperature and pressure
C) Bulb temperature and evaporator pressure
D) Condenser pressure and liquid line temperature
Answer: C) Bulb temperature and evaporator pressure
Explanation: The TXV uses a sensing bulb attached to the suction line to
measure temperature (which corresponds to superheat) and an external
equalizer line to sense evaporator pressure. The valve modulates flow to
maintain a constant superheat at the evaporator outlet by balancing
these two opposing forces.
