G2 Gas Technician Module 20 Revised
Exam 2026 Questions and Answers
What prevents the water in a hydronic heating system from boiling into steam
when the system is operating above the atmospheric temperature? - Correct
Answer -Pressurization of the system
List the four subsystems of a hydronic space heating system? - Correct Answer -
Heat Source, Circulation system, Heat Emitters, Control system
What must be done to protect the potable water supply to a hot water boiler? -
Correct Answer -Approved backflow preventer installed in the water supply
Above what input is a low water cut-off a required component of a hot water
boiler? - Correct Answer -400,000 BTU
Why are cast-iron sectional boilers used only in closed loop hydronic system? -
Correct Answer -Purge itself of Air and reduces corrosion
Why does a copper fin-tube boiler require less surface area to transfer heat than a
steel fire tube boiler? - Correct Answer -Copper Tube has a higher thermal
conductivity than steel tube
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, What happens to the water vapour in the combustion products if the flue gases are
cooled below the dew point? - Correct Answer -The water vapour condenses into
liquid state
How is an automatic vent damper interlocked to ensure it is in the open position
before the burner can fire? - Correct Answer -The damper actuator has a proving
switch that is interlocked with the thermostat controlling the burner
Which is the simplest hydronic distribution system? - Correct Answer -Single
Series Circuit
What two purposes are served when a combination system is used? - Correct
Answer -Space Heating and Domestic Water
May chemical additives be introduced into a combustion system? - Correct Answer
-No
What device within a closed hydronic system is required to provide provision for
the volumetric expansion of the system fluid under normal operating condition? -
Correct Answer -Expansion Tank
List four common air elimination devices used on hydronic heating system. -
Correct Answer -Manual Air Vent, Automatic Air vent, Air purgers, and
Microbubblers
©COPYRIGHT 2025 ALL RIGHTS RESERVED 2
Exam 2026 Questions and Answers
What prevents the water in a hydronic heating system from boiling into steam
when the system is operating above the atmospheric temperature? - Correct
Answer -Pressurization of the system
List the four subsystems of a hydronic space heating system? - Correct Answer -
Heat Source, Circulation system, Heat Emitters, Control system
What must be done to protect the potable water supply to a hot water boiler? -
Correct Answer -Approved backflow preventer installed in the water supply
Above what input is a low water cut-off a required component of a hot water
boiler? - Correct Answer -400,000 BTU
Why are cast-iron sectional boilers used only in closed loop hydronic system? -
Correct Answer -Purge itself of Air and reduces corrosion
Why does a copper fin-tube boiler require less surface area to transfer heat than a
steel fire tube boiler? - Correct Answer -Copper Tube has a higher thermal
conductivity than steel tube
©COPYRIGHT 2025 ALL RIGHTS RESERVED 1
, What happens to the water vapour in the combustion products if the flue gases are
cooled below the dew point? - Correct Answer -The water vapour condenses into
liquid state
How is an automatic vent damper interlocked to ensure it is in the open position
before the burner can fire? - Correct Answer -The damper actuator has a proving
switch that is interlocked with the thermostat controlling the burner
Which is the simplest hydronic distribution system? - Correct Answer -Single
Series Circuit
What two purposes are served when a combination system is used? - Correct
Answer -Space Heating and Domestic Water
May chemical additives be introduced into a combustion system? - Correct Answer
-No
What device within a closed hydronic system is required to provide provision for
the volumetric expansion of the system fluid under normal operating condition? -
Correct Answer -Expansion Tank
List four common air elimination devices used on hydronic heating system. -
Correct Answer -Manual Air Vent, Automatic Air vent, Air purgers, and
Microbubblers
©COPYRIGHT 2025 ALL RIGHTS RESERVED 2
