G2 Practice Exam Questions with Correct
Answers 2025/2026 Rated A+
The ventor motor on a power vent water heater fails, this component prevents operation?
a)Pressure relief valve
b)ECO switch
c)High limit switch
d)Pressure Switch - CORRECT ANSWER -Pressure Switch
What is the ignition temperature for natural gas?
a)920 degrees Fahrenheit
b)1000 degrees Fahrenheit
c)1300 degrees Fahrenheit
d)3600 degrees Fahrenheit - CORRECT ANSWER -1300 Degree F
A yellow flame is the result where there is no premixing of primary air with gas prior to
ignition. What is this type of flame called?
a)A Bunsen flame
b)A luminous flame
c)A gas starved flame
d)An air starved flame - CORRECT ANSWER -a luminous flame
When diluting muriatic acid with water:
a)Add the acid to the water
b)Add the water to the acid
c)Add water to the acid one drop at a time for 10 drops then add the full amount
,d)Add acid to the water one drop at a time for 10 drops then add the full amount - CORRECT
ANSWER -2)add acid to the water
As the length of an electrical run increases, it may be necessary to:
a)Increase the wire size
B)Use a different type of conductor
c)Decrease the fuse size
d)Increase the fuse size - CORRECT ANSWER -a) increase the wire size
A blue flame is the result of mixing primary air with gas prior to ignition. What is this type of
flame referred to as?
a)A Bunsen flame
b)A luminous flame
c)A gas rich flame
d)An air rich flame - CORRECT ANSWER -a bunsen flame
What type of flux should be used when brazing copper tubing for propane systems?
a)Corrosive type
b)Non-corrosive type
c)Liquid type
d)Paste type - CORRECT ANSWER -non corrosive type
What shall be provided in the gas supply line to boiler room or confined area where the total
input of the appliances is in excess of 2,000,000 Btuh (585 kW)?
a)A back check valve
b)An accessible automatic reset valve
,c)An approved mechanical non-electric fast closing valve
d)An identified accessible emergency manual shut off valve - CORRECT ANSWER -an identified
accessible emergency manual shut off valve
What must be done if cracks are discovered in a heat exchanger of a furnace?
a)repair the cracks with an approved welding process
b)repair the cracks with furnace cement
c)repair the cracks with hi temperature tape
d)replace the heat exchanger - CORRECT ANSWER -replace the heat exchanger
Brazing rods with _______________ should not be used for natural gas/propane as it reacts
with the sulfur in the fuel making the brazed joint brittle.
Copper
Silver
Cadmium
Phosphorous - CORRECT ANSWER -Phosphorous
"Temperature rise", when applied to a hot water heater is the:
Difference between outdoor temperature and the flue gas temperature
Water temperature difference across the heater
Temperature difference between the bottom and top of the heater
Height of the hot water piping system - CORRECT ANSWER -water temperature difference across
the heater
What is the boiling point for propane gas?
-44 F
-920 F
, 0F
32 F - CORRECT ANSWER --44 F
A one cubic foot test dial on a natural gas meter makes one revolution every 60
seconds.Approximately how many Btuh are being generated? (#16-176) (A one cubic foot test
dial on a
natural gas meter makes one revolution every 60 seconds. Approximately how many Btuh
arebeing generated?)
30 MBtuh
41 MBtuh
60 MBtuh
82 MBtuh - CORRECT ANSWER -60 MBtuh
When two 10 microfarad capacitors are connected in parallel, what is the net result?
0 mf
5 mf
10 mf
20 mf - CORRECT ANSWER -20 mf
Most thermostatically controlled domestic hot water heaters utilize:
bi-metallic sensing
Rod and tube sensing
Liquid filled sensors
Vapour filled sensors - CORRECT ANSWER -Rod and Tube sensing
5 boilers with draft diverters are to be installed in an enclosed furnace room. The volume ofthe
room is 15,000 cubic feet. The input for each boiler is 300,000 Btuh. What size free air opening
Answers 2025/2026 Rated A+
The ventor motor on a power vent water heater fails, this component prevents operation?
a)Pressure relief valve
b)ECO switch
c)High limit switch
d)Pressure Switch - CORRECT ANSWER -Pressure Switch
What is the ignition temperature for natural gas?
a)920 degrees Fahrenheit
b)1000 degrees Fahrenheit
c)1300 degrees Fahrenheit
d)3600 degrees Fahrenheit - CORRECT ANSWER -1300 Degree F
A yellow flame is the result where there is no premixing of primary air with gas prior to
ignition. What is this type of flame called?
a)A Bunsen flame
b)A luminous flame
c)A gas starved flame
d)An air starved flame - CORRECT ANSWER -a luminous flame
When diluting muriatic acid with water:
a)Add the acid to the water
b)Add the water to the acid
c)Add water to the acid one drop at a time for 10 drops then add the full amount
,d)Add acid to the water one drop at a time for 10 drops then add the full amount - CORRECT
ANSWER -2)add acid to the water
As the length of an electrical run increases, it may be necessary to:
a)Increase the wire size
B)Use a different type of conductor
c)Decrease the fuse size
d)Increase the fuse size - CORRECT ANSWER -a) increase the wire size
A blue flame is the result of mixing primary air with gas prior to ignition. What is this type of
flame referred to as?
a)A Bunsen flame
b)A luminous flame
c)A gas rich flame
d)An air rich flame - CORRECT ANSWER -a bunsen flame
What type of flux should be used when brazing copper tubing for propane systems?
a)Corrosive type
b)Non-corrosive type
c)Liquid type
d)Paste type - CORRECT ANSWER -non corrosive type
What shall be provided in the gas supply line to boiler room or confined area where the total
input of the appliances is in excess of 2,000,000 Btuh (585 kW)?
a)A back check valve
b)An accessible automatic reset valve
,c)An approved mechanical non-electric fast closing valve
d)An identified accessible emergency manual shut off valve - CORRECT ANSWER -an identified
accessible emergency manual shut off valve
What must be done if cracks are discovered in a heat exchanger of a furnace?
a)repair the cracks with an approved welding process
b)repair the cracks with furnace cement
c)repair the cracks with hi temperature tape
d)replace the heat exchanger - CORRECT ANSWER -replace the heat exchanger
Brazing rods with _______________ should not be used for natural gas/propane as it reacts
with the sulfur in the fuel making the brazed joint brittle.
Copper
Silver
Cadmium
Phosphorous - CORRECT ANSWER -Phosphorous
"Temperature rise", when applied to a hot water heater is the:
Difference between outdoor temperature and the flue gas temperature
Water temperature difference across the heater
Temperature difference between the bottom and top of the heater
Height of the hot water piping system - CORRECT ANSWER -water temperature difference across
the heater
What is the boiling point for propane gas?
-44 F
-920 F
, 0F
32 F - CORRECT ANSWER --44 F
A one cubic foot test dial on a natural gas meter makes one revolution every 60
seconds.Approximately how many Btuh are being generated? (#16-176) (A one cubic foot test
dial on a
natural gas meter makes one revolution every 60 seconds. Approximately how many Btuh
arebeing generated?)
30 MBtuh
41 MBtuh
60 MBtuh
82 MBtuh - CORRECT ANSWER -60 MBtuh
When two 10 microfarad capacitors are connected in parallel, what is the net result?
0 mf
5 mf
10 mf
20 mf - CORRECT ANSWER -20 mf
Most thermostatically controlled domestic hot water heaters utilize:
bi-metallic sensing
Rod and tube sensing
Liquid filled sensors
Vapour filled sensors - CORRECT ANSWER -Rod and Tube sensing
5 boilers with draft diverters are to be installed in an enclosed furnace room. The volume ofthe
room is 15,000 cubic feet. The input for each boiler is 300,000 Btuh. What size free air opening
