How much separation is commonly needed between the vent and intake pipes of a condensing furnace that
pass through a roof?
a. 24 inches
b. 12 inches
c. 6 inches
d. 3 inches
[Ques. 2] What happens first when there is a call-for-heat signal to a furnace equipped with a motor-driven vent
damper?
a. The burners light to warm a bi-metal element.
b. A switch in the damper closes to start the burner.
c. A motor opens the vent damper.
d. The burners light to start the motor.
[Ques. 3] The National Fuel Gas Code category of vent system used with a natural draft furnace is _____.
a. Category I
b. Category II
c. Category III
d. Category IV
[Ques. 4] When selecting a gas furnace, how is its heating capacity determined?
a. Its input rating must exactly match the calculated heat loss of the structure.
b. Its output rating must exactly match the calculated heat loss of the structure.
c. Its output rating can be up to 150 percent of the calculated heat loss of the structure.
d. Its output rating should be no less than 95 percent of the calculated heat loss of the structure.
[Ques. 5] If excess carbon monoxide is present in a building heated by a gas furnace, it is likely a sign of _____.
a. incomplete combustion
b. complete combustion
c. a contaminated fuel supply
d. too much oxygen
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