G2 Gas Technician Module 20 Revised exam 2023 with 100% correct 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 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 t