MECHANICAL PRACTICE EXAM QUESTIONS AND ANSWERS | MECHANICAL EXAM
PREP & STUDY GUIDE 2026/2027
What turns off the gas if there is a problem at a water heater and/or gas furnace? -
✔✔Thermocouple
Where is the only place cross connection is allowed/acceptable? - ✔✔On the Brine Line of a
water ionization system
Appliance fuel connectors shall have a maximum overall length of - ✔✔6 feet
A water temperature limiting device shall be provided to limit the hot water supplied bathtub or
whirl pool bathtub to a maximum of - ✔✔120 F
The total fall in a fixture drain due to pipe slope is limited to a maximum of - ✔✔One pipe
diameter
Where a fixture is separately trapped what is the maximum vertical distance permitted fixture
outlet to the trap weir? - ✔✔24 inches
What chimney part prevents moisture from entering between the brick and the flue? -
✔✔Chimney cap/crown
Soot on a gas water heater door indicates: - ✔✔Improper combustion (spillage)
Type B vent and hood must be a minimum of how many feet from the end of the vent? - ✔✔2
feet from the highest penetration
, P-Trap cannot be greater than_____from the bottom of a lavatory basin or sink - ✔✔24''
Atmospheric vacuum breakers: - ✔✔Prevent back flow
What minimum clearance from side &bottom of an openable window to forced fan vent gas
appliance? - ✔✔4'-4'
What is a typical problem with a gas hot water heater supply valve? - ✔✔Carbon Build up
What is the appropriate temperature difference between return and supply A/c? - ✔✔15-20
Delta-T
Gas lines enter a room with a water heater and furnace. Where should the shut off valve be
located? - ✔✔At each appliance
Gas dryer supply line is not being used. Check: - ✔✔Gas line is capped
Incomplete combustion of natural gas produces: - ✔✔Carbon Monoxide; Life expectancy is 6
years
Using a mirror and flashlight to view the heat exchanger on a gas furnace allows you to see -
✔✔Les than 20% of the heat exchanger
The vent connector should slope: - ✔✔Upward going away from the furnace at minimum
quarter inch per foot
How much should a belt deflect when it is under proper tension? - ✔✔About an inch
PREP & STUDY GUIDE 2026/2027
What turns off the gas if there is a problem at a water heater and/or gas furnace? -
✔✔Thermocouple
Where is the only place cross connection is allowed/acceptable? - ✔✔On the Brine Line of a
water ionization system
Appliance fuel connectors shall have a maximum overall length of - ✔✔6 feet
A water temperature limiting device shall be provided to limit the hot water supplied bathtub or
whirl pool bathtub to a maximum of - ✔✔120 F
The total fall in a fixture drain due to pipe slope is limited to a maximum of - ✔✔One pipe
diameter
Where a fixture is separately trapped what is the maximum vertical distance permitted fixture
outlet to the trap weir? - ✔✔24 inches
What chimney part prevents moisture from entering between the brick and the flue? -
✔✔Chimney cap/crown
Soot on a gas water heater door indicates: - ✔✔Improper combustion (spillage)
Type B vent and hood must be a minimum of how many feet from the end of the vent? - ✔✔2
feet from the highest penetration
, P-Trap cannot be greater than_____from the bottom of a lavatory basin or sink - ✔✔24''
Atmospheric vacuum breakers: - ✔✔Prevent back flow
What minimum clearance from side &bottom of an openable window to forced fan vent gas
appliance? - ✔✔4'-4'
What is a typical problem with a gas hot water heater supply valve? - ✔✔Carbon Build up
What is the appropriate temperature difference between return and supply A/c? - ✔✔15-20
Delta-T
Gas lines enter a room with a water heater and furnace. Where should the shut off valve be
located? - ✔✔At each appliance
Gas dryer supply line is not being used. Check: - ✔✔Gas line is capped
Incomplete combustion of natural gas produces: - ✔✔Carbon Monoxide; Life expectancy is 6
years
Using a mirror and flashlight to view the heat exchanger on a gas furnace allows you to see -
✔✔Les than 20% of the heat exchanger
The vent connector should slope: - ✔✔Upward going away from the furnace at minimum
quarter inch per foot
How much should a belt deflect when it is under proper tension? - ✔✔About an inch
