NFI Exam Review ACTUAL UPDATED
QUESTIONS AND CORRECT ANSWERS
Combustion Requirments - CORRECT ANSWERS✅✅Air, Fuel, Heat
Complete Combustion Produces - CORRECT ANSWERS✅✅Water vapor, carbon dioxide,
heat, and non combustible ashes
incomplete combustion produces - CORRECT ANSWERS✅✅carbon monoxide,
hydrocarbons, and other gases
rate at which fuel burns is controlled by - CORRECT ANSWERS✅✅the amount of
available air
air to fuel ratio is a - CORRECT ANSWERS✅✅critical factor in obtaining optimum fuel
combustion
BTU - CORRECT ANSWERS✅✅British Thermal Unit, The amount of energy needed to
heat one pound of water one degree Fahrenheit
wood ignites at - CORRECT ANSWERS✅✅450-550 F
natural gas ignites at - CORRECT ANSWERS✅✅1,150 F
propane ignites at - CORRECT ANSWERS✅✅920-1120 F
electric spark temp - CORRECT ANSWERS✅✅1,700 F
hot surface igniter temp - CORRECT ANSWERS✅✅2,400 F
butane lighter temp - CORRECT ANSWERS✅✅3,200 F
,stick match temp - CORRECT ANSWERS✅✅3,000 F
cigarette temp - CORRECT ANSWERS✅✅500-800 F
For complete combustion: air is ______ % oxygen + _____ % nitrogen - CORRECT
ANSWERS✅✅20 : 80
for complete combustion, ____ molecules of _____ need to be mixed with _____ molecule of
_________ in the presence of ____ - CORRECT ANSWERS✅✅2 oxygen : 1 fuel : heat
When complete combustion happens ______ are released - CORRECT ANSWERS✅✅heat,
carbon dioxide (C02), water vapor (H20), and nitrogen (N)
Carbon monoxide is dangerous because - CORRECT ANSWERS✅✅it mixes with blood
and reduces oxygen carrying capacity
Aldehydes - CORRECT ANSWERS✅✅chemical compounds that have a strong pungent
odor
Carbon monoxide is ________ when aldehydes are present - CORRECT
ANSWERS✅✅present
Aldehydes result from - CORRECT ANSWERS✅✅flame impingement and through the
presence of contaminated air
Efficiency - CORRECT ANSWERS✅✅Heat output divided by heat input (percentage of
heat transferred to room)
3 Ts of efficiency - CORRECT ANSWERS✅✅Temperature, turbulence, time
Temperature (efficiency) - CORRECT ANSWERS✅✅minimum ignition temp
, Turbulence (efficiency) - CORRECT ANSWERS✅✅fuel most collide with oxygen
molecules (refers to the degree of fuel and air mixing that occurs in combustion zone)
Time (efficiency) - CORRECT ANSWERS✅✅amount of time fuel gases remain in the high
temp zone. also known as "residence time"
Heat Transfer Efficiency - CORRECT ANSWERS✅✅refers to the percentage of heat
generated by combustion actually transferred to room
High heat transfer efficiency is normally associated with: - CORRECT
ANSWERS✅✅Appliance having proportionally large exterior surfaces with good heat
radiating properties
Long residence time of the not gases in the Appliance
Adequate turbulence inside the appliance to property transfer heat from the fire chamber to
appliance walls
Rapid heat transfer through the walls of the appliance
Adequate air movement (convection) outside
2 types of factory built fireplaces - CORRECT ANSWERS✅✅radiating and circulating
Radiant design - CORRECT ANSWERS✅✅transmits heat energy from firebox opening by
direct radiation to the space in front of it. (do not have grills or louvers on the face, heat
moving blowers not avail.)
circulating design - CORRECT ANSWERS✅✅adds function of heat transfer via heated air
convection by circulating air around the fire chamber and releasing into space to be heated
through grills and louvers
QUESTIONS AND CORRECT ANSWERS
Combustion Requirments - CORRECT ANSWERS✅✅Air, Fuel, Heat
Complete Combustion Produces - CORRECT ANSWERS✅✅Water vapor, carbon dioxide,
heat, and non combustible ashes
incomplete combustion produces - CORRECT ANSWERS✅✅carbon monoxide,
hydrocarbons, and other gases
rate at which fuel burns is controlled by - CORRECT ANSWERS✅✅the amount of
available air
air to fuel ratio is a - CORRECT ANSWERS✅✅critical factor in obtaining optimum fuel
combustion
BTU - CORRECT ANSWERS✅✅British Thermal Unit, The amount of energy needed to
heat one pound of water one degree Fahrenheit
wood ignites at - CORRECT ANSWERS✅✅450-550 F
natural gas ignites at - CORRECT ANSWERS✅✅1,150 F
propane ignites at - CORRECT ANSWERS✅✅920-1120 F
electric spark temp - CORRECT ANSWERS✅✅1,700 F
hot surface igniter temp - CORRECT ANSWERS✅✅2,400 F
butane lighter temp - CORRECT ANSWERS✅✅3,200 F
,stick match temp - CORRECT ANSWERS✅✅3,000 F
cigarette temp - CORRECT ANSWERS✅✅500-800 F
For complete combustion: air is ______ % oxygen + _____ % nitrogen - CORRECT
ANSWERS✅✅20 : 80
for complete combustion, ____ molecules of _____ need to be mixed with _____ molecule of
_________ in the presence of ____ - CORRECT ANSWERS✅✅2 oxygen : 1 fuel : heat
When complete combustion happens ______ are released - CORRECT ANSWERS✅✅heat,
carbon dioxide (C02), water vapor (H20), and nitrogen (N)
Carbon monoxide is dangerous because - CORRECT ANSWERS✅✅it mixes with blood
and reduces oxygen carrying capacity
Aldehydes - CORRECT ANSWERS✅✅chemical compounds that have a strong pungent
odor
Carbon monoxide is ________ when aldehydes are present - CORRECT
ANSWERS✅✅present
Aldehydes result from - CORRECT ANSWERS✅✅flame impingement and through the
presence of contaminated air
Efficiency - CORRECT ANSWERS✅✅Heat output divided by heat input (percentage of
heat transferred to room)
3 Ts of efficiency - CORRECT ANSWERS✅✅Temperature, turbulence, time
Temperature (efficiency) - CORRECT ANSWERS✅✅minimum ignition temp
, Turbulence (efficiency) - CORRECT ANSWERS✅✅fuel most collide with oxygen
molecules (refers to the degree of fuel and air mixing that occurs in combustion zone)
Time (efficiency) - CORRECT ANSWERS✅✅amount of time fuel gases remain in the high
temp zone. also known as "residence time"
Heat Transfer Efficiency - CORRECT ANSWERS✅✅refers to the percentage of heat
generated by combustion actually transferred to room
High heat transfer efficiency is normally associated with: - CORRECT
ANSWERS✅✅Appliance having proportionally large exterior surfaces with good heat
radiating properties
Long residence time of the not gases in the Appliance
Adequate turbulence inside the appliance to property transfer heat from the fire chamber to
appliance walls
Rapid heat transfer through the walls of the appliance
Adequate air movement (convection) outside
2 types of factory built fireplaces - CORRECT ANSWERS✅✅radiating and circulating
Radiant design - CORRECT ANSWERS✅✅transmits heat energy from firebox opening by
direct radiation to the space in front of it. (do not have grills or louvers on the face, heat
moving blowers not avail.)
circulating design - CORRECT ANSWERS✅✅adds function of heat transfer via heated air
convection by circulating air around the fire chamber and releasing into space to be heated
through grills and louvers
