G2 Gas Technician Module 20 Revised
Test Questions With Solved Solutions.
What prevents the water in a hydronic heating system from boiling into steam when the system is
operating above the atmospheric temperature? - Answer Pressurization of the system
List the four subsystems of a hydronic space heating system? - Answer Heat Source, Circulation system,
Heat Emitters, Control system
What must be done to protect the potable water supply to a hot water boiler? - 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? - Answer 400,000
BTU
Why are cast-iron sectional boilers used only in closed loop hydronic system? - 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?
- Answer Copper Tube has a higher thermal conductivity than steel tube
What happens to the water vapour in the combustion products if the flue gases are cooled below the
dew point? - 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? - Answer The damper actuator has a proving switch that is interlocked with the thermostat
controlling the burner
Which is the simplest hydronic distribution system? - Answer Single Series Circuit
What two purposes are served when a combination system is used? - Answer Space Heating and
Domestic Water
, May chemical additives be introduced into a combustion system? - 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? - Answer Expansion Tank
List four common air elimination devices used on hydronic heating system. - Answer Manual Air Vent,
Automatic Air vent, Air purgers, and Microbubblers
Which device within a hydronic heating system is required to release water during an unsafe condition
caused by excessive pressures? - Answer ASME Pressure Relief Valve
Which type of valve is best suited for throttling flow? - Answer Globe Valve or Gate Valve
What two types of drive heads can be used on a thermostatic radiator valve? - Answer Mechanical and
electrical
On three and four-way mixing valves, where does the mixing take place? - Answer Within the valve
body
Where should an outdoor temperature sensor be placed? - Answer Away from direct sunlight, away
from other heat sources and away from a shielding structure
What are the three general methods used to control temperature zones in a building? - Answer
Circulating pumps, zone valves, and thermostatic radiator valves
What is the purpose of a balancing valve? - Answer Modulate and balance the flow through each
branch
Where is the circulating pump in a hydronic system located? - Answer Typically on the supply side
Test Questions With Solved Solutions.
What prevents the water in a hydronic heating system from boiling into steam when the system is
operating above the atmospheric temperature? - Answer Pressurization of the system
List the four subsystems of a hydronic space heating system? - Answer Heat Source, Circulation system,
Heat Emitters, Control system
What must be done to protect the potable water supply to a hot water boiler? - 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? - Answer 400,000
BTU
Why are cast-iron sectional boilers used only in closed loop hydronic system? - 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?
- Answer Copper Tube has a higher thermal conductivity than steel tube
What happens to the water vapour in the combustion products if the flue gases are cooled below the
dew point? - 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? - Answer The damper actuator has a proving switch that is interlocked with the thermostat
controlling the burner
Which is the simplest hydronic distribution system? - Answer Single Series Circuit
What two purposes are served when a combination system is used? - Answer Space Heating and
Domestic Water
, May chemical additives be introduced into a combustion system? - 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? - Answer Expansion Tank
List four common air elimination devices used on hydronic heating system. - Answer Manual Air Vent,
Automatic Air vent, Air purgers, and Microbubblers
Which device within a hydronic heating system is required to release water during an unsafe condition
caused by excessive pressures? - Answer ASME Pressure Relief Valve
Which type of valve is best suited for throttling flow? - Answer Globe Valve or Gate Valve
What two types of drive heads can be used on a thermostatic radiator valve? - Answer Mechanical and
electrical
On three and four-way mixing valves, where does the mixing take place? - Answer Within the valve
body
Where should an outdoor temperature sensor be placed? - Answer Away from direct sunlight, away
from other heat sources and away from a shielding structure
What are the three general methods used to control temperature zones in a building? - Answer
Circulating pumps, zone valves, and thermostatic radiator valves
What is the purpose of a balancing valve? - Answer Modulate and balance the flow through each
branch
Where is the circulating pump in a hydronic system located? - Answer Typically on the supply side
