NFI Exam Review QUESTIONS WITH 100% CORRECT
ANSWERS.
Combustion requirements (3) - (ANSWERS)air, fuel, heat !@#$%%%%%
%%%%%%
Complete combustion produces (4) - (ANSWERS)water vapor, carbon dioxide, heat, and non
combustible ashes
Incomplete combustion produces (3) - (ANSWERS)carbon monoxide, hydrocarbons, and other
gases
Rate at which fuel burns is controlled by - (ANSWERS)the amount of available air
Air to fuel ratio is a - (ANSWERS)critical factor in obtaining optimum fuel combustion
Btu - (ANSWERS)british thermal unit, the amount of energy needed to heat one pound of water
one degree fahrenheit
Wood ignites at - (ANSWERS)450-550 f
Natural gas ignites at - (ANSWERS)1,150 f
Propane ignites at - (ANSWERS)920-1120 f
Electric spark temp - (ANSWERS)1,700 f
Hot surface igniter temp - (ANSWERS)2,400 f
Butane lighter temp - (ANSWERS)3,200 f
Stick match temp - (ANSWERS)3,000 f
Cigarette temp - (ANSWERS)500-800 f
For complete combustion: air is ______ % oxygen + _____ % nitrogen - (ANSWERS)20 : 80
For complete combustion, __(qty)__ molecules of __(part)___ need to be mixed with ___(qty)__
molecule of _____(part)____ in the presence of __(part)__ - (ANSWERS)2 oxygen : 1 fuel : heat
When complete combustion happens __(4 things)___ are released - (ANSWERS)heat, carbon
dioxide (c02), water vapor (h20), and nitrogen (n)
Carbon monoxide is dangerous because (other than senseless) - (ANSWERS)it mixes with
blood and reduces oxygen carrying capacity
,NFI Exam Review QUESTIONS WITH 100% CORRECT
ANSWERS.
Aldehydes - (ANSWERS)chemical compounds that have a strong pungent odor!@#$%%%%%
%%%%%%
Carbon monoxide is ________ when aldehydes are present - (ANSWERS)present
Aldehydes result from - (ANSWERS)flame impingement and through the presence of
contaminated air
Efficiency formula - (ANSWERS)heat output divided by heat input (percentage of heat
transferred to room)
3 ts of efficiency - (ANSWERS)temperature, turbulence, time
Temperature (efficiency) - (ANSWERS)minimum ignition temp
Turbulence (efficiency) - (ANSWERS)fuel must collide with oxygen molecules (refers to the
degree of fuel and air mixing that occurs in combustion zone)
Time (efficiency) - (ANSWERS)amount of time fuel gases remain in the high temp zone. Also
known as "residence time"
Heat transfer efficiency - (ANSWERS)refers to the percentage of heat generated by combustion
actually transferred to room
High heat transfer efficiency is normally associated with: (5 things) - (ANSWERS)appliance
having proportionally large exterior surfaces with good heat radiating properties
Long residence time of the hot 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 - (ANSWERS)radiating and circulating
Radiant design - (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.)
, NFI Exam Review QUESTIONS WITH 100% CORRECT
ANSWERS.
Circulating design - (ANSWERS)adds function of heat transfer via heated air convection by
!@#$%%%%%
circulating air around the fire chamber and releasing into space to be heated through
%%%%%% grills and
louvers
Built-in, high efficiency fireplaces - (ANSWERS)contain efficient combustion and convection
champers that are enclosed in an insulated metal cabinet. Can be enclosed in close proximity
to combustibles
Fireplace inserts and hearth stoves are - (ANSWERS)designed to improve the efficiency of an
open fireplace and retain the general appearance of the fireplace while improving its efficiency
Hearth appliance construction - (ANSWERS)modern solid fuel appliance designed to introduce
combustion air through specific and controllable air inlets and are controlled by the user
Most controlled combustion devices are made of (metals) - (ANSWERS)cast iron or steel
Cast iron (fireplace) - (ANSWERS)made from molds, can be decorative
Steel (fireplace) - (ANSWERS)welded joints that need no service, some use steel fireboxes
inside decorative cast iron
Soapstone (fireplace) - (ANSWERS)lower thermal conductivity, delivers heat slowly but retain
and delivers heat longer
Conduction - (ANSWERS)direct transmission of heat from one surface of solid material to
another surface of solid material
Convection - (ANSWERS)transfer of heat through a gas or liquid, including air, the transfer of
heated air between areas of unequal density. Natural occurs between heavier, cooler air and
lighter, warmer air
Forced convection occurs - (ANSWERS)by mechanical means, aka electric blower
Radiation - (ANSWERS)emission of waves of infrared energy, converted to heat on contact with
solid surfaces
Radiant appliances - (ANSWERS)single wall, exterior wall is firebox wall. Generally required for
large open spaces than small numerous rooms
Convection appliances (3 things) - (ANSWERS)double wall construction, allows room air to
circulate, convection currents, blower increases the amount and distance of heated air
circulation
ANSWERS.
Combustion requirements (3) - (ANSWERS)air, fuel, heat !@#$%%%%%
%%%%%%
Complete combustion produces (4) - (ANSWERS)water vapor, carbon dioxide, heat, and non
combustible ashes
Incomplete combustion produces (3) - (ANSWERS)carbon monoxide, hydrocarbons, and other
gases
Rate at which fuel burns is controlled by - (ANSWERS)the amount of available air
Air to fuel ratio is a - (ANSWERS)critical factor in obtaining optimum fuel combustion
Btu - (ANSWERS)british thermal unit, the amount of energy needed to heat one pound of water
one degree fahrenheit
Wood ignites at - (ANSWERS)450-550 f
Natural gas ignites at - (ANSWERS)1,150 f
Propane ignites at - (ANSWERS)920-1120 f
Electric spark temp - (ANSWERS)1,700 f
Hot surface igniter temp - (ANSWERS)2,400 f
Butane lighter temp - (ANSWERS)3,200 f
Stick match temp - (ANSWERS)3,000 f
Cigarette temp - (ANSWERS)500-800 f
For complete combustion: air is ______ % oxygen + _____ % nitrogen - (ANSWERS)20 : 80
For complete combustion, __(qty)__ molecules of __(part)___ need to be mixed with ___(qty)__
molecule of _____(part)____ in the presence of __(part)__ - (ANSWERS)2 oxygen : 1 fuel : heat
When complete combustion happens __(4 things)___ are released - (ANSWERS)heat, carbon
dioxide (c02), water vapor (h20), and nitrogen (n)
Carbon monoxide is dangerous because (other than senseless) - (ANSWERS)it mixes with
blood and reduces oxygen carrying capacity
,NFI Exam Review QUESTIONS WITH 100% CORRECT
ANSWERS.
Aldehydes - (ANSWERS)chemical compounds that have a strong pungent odor!@#$%%%%%
%%%%%%
Carbon monoxide is ________ when aldehydes are present - (ANSWERS)present
Aldehydes result from - (ANSWERS)flame impingement and through the presence of
contaminated air
Efficiency formula - (ANSWERS)heat output divided by heat input (percentage of heat
transferred to room)
3 ts of efficiency - (ANSWERS)temperature, turbulence, time
Temperature (efficiency) - (ANSWERS)minimum ignition temp
Turbulence (efficiency) - (ANSWERS)fuel must collide with oxygen molecules (refers to the
degree of fuel and air mixing that occurs in combustion zone)
Time (efficiency) - (ANSWERS)amount of time fuel gases remain in the high temp zone. Also
known as "residence time"
Heat transfer efficiency - (ANSWERS)refers to the percentage of heat generated by combustion
actually transferred to room
High heat transfer efficiency is normally associated with: (5 things) - (ANSWERS)appliance
having proportionally large exterior surfaces with good heat radiating properties
Long residence time of the hot gases in the appliance
Adequate turbulence inside the appliance to property transfer heat from the fire chamber to
appliance walls
Rapid heat transfer through the walls of the appliance
Adequate air movement (convection) outside
2 types of factory built fireplaces - (ANSWERS)radiating and circulating
Radiant design - (ANSWERS)transmits heat energy from firebox opening by direct radiation to
the space in front of it. (do not have grills or louvers on the face, heat moving blowers not avail.)
, NFI Exam Review QUESTIONS WITH 100% CORRECT
ANSWERS.
Circulating design - (ANSWERS)adds function of heat transfer via heated air convection by
!@#$%%%%%
circulating air around the fire chamber and releasing into space to be heated through
%%%%%% grills and
louvers
Built-in, high efficiency fireplaces - (ANSWERS)contain efficient combustion and convection
champers that are enclosed in an insulated metal cabinet. Can be enclosed in close proximity
to combustibles
Fireplace inserts and hearth stoves are - (ANSWERS)designed to improve the efficiency of an
open fireplace and retain the general appearance of the fireplace while improving its efficiency
Hearth appliance construction - (ANSWERS)modern solid fuel appliance designed to introduce
combustion air through specific and controllable air inlets and are controlled by the user
Most controlled combustion devices are made of (metals) - (ANSWERS)cast iron or steel
Cast iron (fireplace) - (ANSWERS)made from molds, can be decorative
Steel (fireplace) - (ANSWERS)welded joints that need no service, some use steel fireboxes
inside decorative cast iron
Soapstone (fireplace) - (ANSWERS)lower thermal conductivity, delivers heat slowly but retain
and delivers heat longer
Conduction - (ANSWERS)direct transmission of heat from one surface of solid material to
another surface of solid material
Convection - (ANSWERS)transfer of heat through a gas or liquid, including air, the transfer of
heated air between areas of unequal density. Natural occurs between heavier, cooler air and
lighter, warmer air
Forced convection occurs - (ANSWERS)by mechanical means, aka electric blower
Radiation - (ANSWERS)emission of waves of infrared energy, converted to heat on contact with
solid surfaces
Radiant appliances - (ANSWERS)single wall, exterior wall is firebox wall. Generally required for
large open spaces than small numerous rooms
Convection appliances (3 things) - (ANSWERS)double wall construction, allows room air to
circulate, convection currents, blower increases the amount and distance of heated air
circulation
