G2 Gas Technician Module 18 UPDATED
Exam Questions and CORRECT Answers
What is a temperature control made of in a water heater? Which one is the sensing element? -
CORRECT ANSWER- Rod and tube. Rod is steel and tube is copper. Copper is the sensing
element.
Temperature settings on a water heater? - CORRECT ANSWER- Hot - 160 F
Normal - 130 F
Warm - 120 F
What does a unitrol have in it? - CORRECT ANSWER- Temperature and pressure relief
valve, E.C.O., Main Gas valves, Pilot Gas Valve and a gas regulator
What temp does a temperature and pressure relief valve fusible link melt at? Pressure relieve
at? - CORRECT ANSWER- Melts at 210 F and relieves itself at 150 psi
How does a dip tube function? - CORRECT ANSWER- Allows cold water to enter near the
bottom of the tank as hot water exits the top
What do anodes do in a water heater? When do you need to change them? - CORRECT
ANSWER- Prevents the interior of the tank from corroding and should be changed when its
diameter is 3/8"
What are the components of an instantaneous water heater? - CORRECT ANSWER- Pump,
pump control, flow switch, temperature and pressure relief valve, and a limit control
What must be done with a Twinned Water heater system to ensure it runs properly? -
CORRECT ANSWER- Inlet and outlet piping must have equal resistance on each tank.
What clearance must a direct vent water heater have on the burner side? - CORRECT
ANSWER- 3 feet
, What metals are not acceptable in potable water applications? - CORRECT ANSWER-
Ferrous metals
What is the maximum allowable length of supply and return piping in a combination water
heating system? - CORRECT ANSWER- Max supply and return piping is 50 feet
Can you use chemicals in a combination system? - CORRECT ANSWER- No
How do you size the pumps in a combination system? - CORRECT ANSWER- To match the
flow requirements of the heating system
What is the minimum size and type of water heater that is recommended for a combination
system? - CORRECT ANSWER- 40 gallon high-recovery or high efficiency gas-fired water
heater
What temperature difference do you want from inlet to outlet on a combination system? -
CORRECT ANSWER- 20 F
How do you size a circulating pump? - CORRECT ANSWER- 1 gpm for each 10000 btuh
and friction loss is 1 foot for each 40 feet of pipe
What controls the water temp and gas pressure on a direct fired storage heater? - CORRECT
ANSWER- Unitrol
What are the components of a direct fired storage heater(under fired storage heater) -
CORRECT ANSWER- Dip tube, anode, temperature and pressure relief valve, and mixing
valve
What are the components of a hi-efficiency water heater? - CORRECT ANSWER- E.C.O.,
temperature and pressure relief valve, anode and dip tube
What are the normal operating temps of a unitrol - CORRECT ANSWER- 130 F
What does an E.C.O. do? - CORRECT ANSWER- Shuts off gas valve in a high temperature
situation
Exam Questions and CORRECT Answers
What is a temperature control made of in a water heater? Which one is the sensing element? -
CORRECT ANSWER- Rod and tube. Rod is steel and tube is copper. Copper is the sensing
element.
Temperature settings on a water heater? - CORRECT ANSWER- Hot - 160 F
Normal - 130 F
Warm - 120 F
What does a unitrol have in it? - CORRECT ANSWER- Temperature and pressure relief
valve, E.C.O., Main Gas valves, Pilot Gas Valve and a gas regulator
What temp does a temperature and pressure relief valve fusible link melt at? Pressure relieve
at? - CORRECT ANSWER- Melts at 210 F and relieves itself at 150 psi
How does a dip tube function? - CORRECT ANSWER- Allows cold water to enter near the
bottom of the tank as hot water exits the top
What do anodes do in a water heater? When do you need to change them? - CORRECT
ANSWER- Prevents the interior of the tank from corroding and should be changed when its
diameter is 3/8"
What are the components of an instantaneous water heater? - CORRECT ANSWER- Pump,
pump control, flow switch, temperature and pressure relief valve, and a limit control
What must be done with a Twinned Water heater system to ensure it runs properly? -
CORRECT ANSWER- Inlet and outlet piping must have equal resistance on each tank.
What clearance must a direct vent water heater have on the burner side? - CORRECT
ANSWER- 3 feet
, What metals are not acceptable in potable water applications? - CORRECT ANSWER-
Ferrous metals
What is the maximum allowable length of supply and return piping in a combination water
heating system? - CORRECT ANSWER- Max supply and return piping is 50 feet
Can you use chemicals in a combination system? - CORRECT ANSWER- No
How do you size the pumps in a combination system? - CORRECT ANSWER- To match the
flow requirements of the heating system
What is the minimum size and type of water heater that is recommended for a combination
system? - CORRECT ANSWER- 40 gallon high-recovery or high efficiency gas-fired water
heater
What temperature difference do you want from inlet to outlet on a combination system? -
CORRECT ANSWER- 20 F
How do you size a circulating pump? - CORRECT ANSWER- 1 gpm for each 10000 btuh
and friction loss is 1 foot for each 40 feet of pipe
What controls the water temp and gas pressure on a direct fired storage heater? - CORRECT
ANSWER- Unitrol
What are the components of a direct fired storage heater(under fired storage heater) -
CORRECT ANSWER- Dip tube, anode, temperature and pressure relief valve, and mixing
valve
What are the components of a hi-efficiency water heater? - CORRECT ANSWER- E.C.O.,
temperature and pressure relief valve, anode and dip tube
What are the normal operating temps of a unitrol - CORRECT ANSWER- 130 F
What does an E.C.O. do? - CORRECT ANSWER- Shuts off gas valve in a high temperature
situation
