NFI Exam Review exam with complete
solutions
Combustion hRequirements h(3) h- hANSAir, hFuel, hHeat
Complete hCombustion hProduces h(4) h- hANSWater hvapor, hcarbon hdioxide,
hheat, hand hnon hcombustible hashes
incomplete hcombustion hproduces h(3) h- hANScarbon hmonoxide,
hhydrocarbons, hand hother hgases
rate hat hwhich hfuel hburns his hcontrolled hby h- hANSthe hamount hof
havailable hair
air hto hfuel hratio his ha h- hANScritical hfactor hin hobtaining hoptimum hfuel
hcombustion
BTU h- hANSBritish hThermal hUnit, hThe hamount hof henergy hneeded hto
hheat hone hpound hof hwater hone hdegree hFahrenheit
wood hignites hat h- hANS450-550 hF
natural hgas hignites hat h- hANS1,150 hF
propane hignites hat h- hANS920-1120 hF
electric hspark htemp h- hANS1,700 hF
hot hsurface higniter htemp h- hANS2,400 hF
butane hlighter htemp h- hANS3,200 hF
stick hmatch htemp h- hANS3,000 hF
cigarette htemp h- hANS500-800 hF
,For hcomplete hcombustion: hair his h______ h% hoxygen h+ h_____ h%
hnitrogen h- hANS20 h: h80
for hcomplete hcombustion, h__(QTY)__ hmolecules hof h__(PART)___ hneed hto
hbe hmixed hwith h___(QTY)__ hmolecule hof h_____(PART)____ hin hthe
hpresence hof h__(PART)__ h- hANS2 hoxygen h: h1 hfuel h: hheat
When hcomplete hcombustion hhappens h__(4 hthings)___ hare hreleased h-
hANSheat, hcarbon hdioxide h(C02), hwater hvapor h(H20), hand hnitrogen h(N)
Carbon hmonoxide his hdangerous hbecause h(other hthan hsenseless) h-
hANSit hmixes hwith hblood hand hreduces hoxygen hcarrying hcapacity
Aldehydes h- hANSchemical hcompounds hthat hhave ha hstrong hpungent hodor
Carbon hmonoxide his h________ hwhen haldehydes hare hpresent h-
hANSpresent
Aldehydes hresult hfrom h- hANSflame himpingement hand hthrough hthe
hpresence hof hcontaminated hair
Efficiency hformula h- hANSHeat houtput hdivided hby hheat hinput h(percentage
hof hheat htransferred hto hroom)
3 hTs hof hefficiency h- hANSTemperature, hturbulence, htime
Temperature h(efficiency) h- hANSminimum hignition htemp
Turbulence h(efficiency) h- hANSfuel hmust hcollide hwith hoxygen hmolecules
h(refers hto hthe hdegree hof hfuel hand hair hmixing hthat hoccurs hin
hcombustion hzone)
Time h(efficiency) h- hANSamount hof htime hfuel hgases hremain hin hthe
hhigh htemp hzone. halso hknown has h"residence htime"
Heat hTransfer hEfficiency h- hANSrefers hto hthe hpercentage hof hheat
hgenerated hby hcombustion hactually htransferred hto hroom
High hheat htransfer hefficiency his hnormally hassociated hwith: h(5 hthings) h-
hANSAppliance hhaving hproportionally hlarge hexterior hsurfaces hwith hgood
hheat hradiating hproperties
Long hresidence htime hof hthe hhot hgases hin hthe hAppliance h
, Adequate hturbulence hinside hthe happliance hto hproperty htransfer hheat
hfrom hthe hfire hchamber hto happliance hwalls
Rapid hheat htransfer hthrough hthe hwalls hof hthe happliance
Adequate hair hmovement h(convection) houtside
2 htypes hof hfactory hbuilt hfireplaces h- hANSradiating hand hcirculating
Radiant hdesign h- hANStransmits hheat henergy hfrom hfirebox hopening hby
hdirect hradiation hto hthe hspace hin hfront hof hit. h(do hnot hhave hgrills hor
hlouvers hon hthe hface, hheat hmoving hblowers hnot havail.)
circulating hdesign h- hANSadds hfunction hof hheat htransfer hvia hheated hair
hconvection hby hcirculating hair haround hthe hfire hchamber hand hreleasing
hinto hspace hto hbe hheated hthrough hgrills hand hlouvers
Built-in, hhigh hefficiency hfireplaces h- hANScontain hefficient hcombustion hand
hconvection hchampers hthat hare henclosed hin han hinsulated hmetal hcabinet.
hCan hbe henclosed hin hclose hproximity hto hcombustibles
Fireplace hinserts hand hhearth hstoves hare h- hANSdesigned hto himprove
hthe hefficiency hof han hopen hfireplace hand hretain hthe hgeneral
happearance hof hthe hfireplace hwhile himproving hits hefficiency
Hearth happliance hconstruction h- hANSmodern hsolid hfuel happliance
hdesigned hto hintroduce hcombustion hair hthrough hspecific hand hcontrollable
hair hinlets hand hare hcontrolled hby hthe huser
Most hcontrolled hcombustion hdevices hare hmade hof h(metals) h- hANScast
hiron hor hsteel
Cast hIron h(fireplace) h- hANSmade hfrom hmolds, hcan hbe hdecorative
Steel h(fireplace) h- hANSwelded hjoints hthat hneed hno hservice, hsome huse
hsteel hfireboxes hinside hdecorative hcast hiron
Soapstone h(fireplace) h- hANSlower hthermal hconductivity, hdelivers hheat
hslowly hbut hretain hand hdelivers hheat hlonger
Conduction h- hANSdirect htransmission hof hheat hfrom hone hsurface hof
hsolid hmaterial hto hanother hsurface hof hsolid hmaterial
Convection h- hANStransfer hof hheat hthrough ha hgas hor hliquid, hincluding
hair, hthe htransfer hof hheated hair hbetween hareas hof hunequal hdensity.
hNatural hoccurs hbetween hheavier, hcooler hair hand hlighter, hwarmer hair
solutions
Combustion hRequirements h(3) h- hANSAir, hFuel, hHeat
Complete hCombustion hProduces h(4) h- hANSWater hvapor, hcarbon hdioxide,
hheat, hand hnon hcombustible hashes
incomplete hcombustion hproduces h(3) h- hANScarbon hmonoxide,
hhydrocarbons, hand hother hgases
rate hat hwhich hfuel hburns his hcontrolled hby h- hANSthe hamount hof
havailable hair
air hto hfuel hratio his ha h- hANScritical hfactor hin hobtaining hoptimum hfuel
hcombustion
BTU h- hANSBritish hThermal hUnit, hThe hamount hof henergy hneeded hto
hheat hone hpound hof hwater hone hdegree hFahrenheit
wood hignites hat h- hANS450-550 hF
natural hgas hignites hat h- hANS1,150 hF
propane hignites hat h- hANS920-1120 hF
electric hspark htemp h- hANS1,700 hF
hot hsurface higniter htemp h- hANS2,400 hF
butane hlighter htemp h- hANS3,200 hF
stick hmatch htemp h- hANS3,000 hF
cigarette htemp h- hANS500-800 hF
,For hcomplete hcombustion: hair his h______ h% hoxygen h+ h_____ h%
hnitrogen h- hANS20 h: h80
for hcomplete hcombustion, h__(QTY)__ hmolecules hof h__(PART)___ hneed hto
hbe hmixed hwith h___(QTY)__ hmolecule hof h_____(PART)____ hin hthe
hpresence hof h__(PART)__ h- hANS2 hoxygen h: h1 hfuel h: hheat
When hcomplete hcombustion hhappens h__(4 hthings)___ hare hreleased h-
hANSheat, hcarbon hdioxide h(C02), hwater hvapor h(H20), hand hnitrogen h(N)
Carbon hmonoxide his hdangerous hbecause h(other hthan hsenseless) h-
hANSit hmixes hwith hblood hand hreduces hoxygen hcarrying hcapacity
Aldehydes h- hANSchemical hcompounds hthat hhave ha hstrong hpungent hodor
Carbon hmonoxide his h________ hwhen haldehydes hare hpresent h-
hANSpresent
Aldehydes hresult hfrom h- hANSflame himpingement hand hthrough hthe
hpresence hof hcontaminated hair
Efficiency hformula h- hANSHeat houtput hdivided hby hheat hinput h(percentage
hof hheat htransferred hto hroom)
3 hTs hof hefficiency h- hANSTemperature, hturbulence, htime
Temperature h(efficiency) h- hANSminimum hignition htemp
Turbulence h(efficiency) h- hANSfuel hmust hcollide hwith hoxygen hmolecules
h(refers hto hthe hdegree hof hfuel hand hair hmixing hthat hoccurs hin
hcombustion hzone)
Time h(efficiency) h- hANSamount hof htime hfuel hgases hremain hin hthe
hhigh htemp hzone. halso hknown has h"residence htime"
Heat hTransfer hEfficiency h- hANSrefers hto hthe hpercentage hof hheat
hgenerated hby hcombustion hactually htransferred hto hroom
High hheat htransfer hefficiency his hnormally hassociated hwith: h(5 hthings) h-
hANSAppliance hhaving hproportionally hlarge hexterior hsurfaces hwith hgood
hheat hradiating hproperties
Long hresidence htime hof hthe hhot hgases hin hthe hAppliance h
, Adequate hturbulence hinside hthe happliance hto hproperty htransfer hheat
hfrom hthe hfire hchamber hto happliance hwalls
Rapid hheat htransfer hthrough hthe hwalls hof hthe happliance
Adequate hair hmovement h(convection) houtside
2 htypes hof hfactory hbuilt hfireplaces h- hANSradiating hand hcirculating
Radiant hdesign h- hANStransmits hheat henergy hfrom hfirebox hopening hby
hdirect hradiation hto hthe hspace hin hfront hof hit. h(do hnot hhave hgrills hor
hlouvers hon hthe hface, hheat hmoving hblowers hnot havail.)
circulating hdesign h- hANSadds hfunction hof hheat htransfer hvia hheated hair
hconvection hby hcirculating hair haround hthe hfire hchamber hand hreleasing
hinto hspace hto hbe hheated hthrough hgrills hand hlouvers
Built-in, hhigh hefficiency hfireplaces h- hANScontain hefficient hcombustion hand
hconvection hchampers hthat hare henclosed hin han hinsulated hmetal hcabinet.
hCan hbe henclosed hin hclose hproximity hto hcombustibles
Fireplace hinserts hand hhearth hstoves hare h- hANSdesigned hto himprove
hthe hefficiency hof han hopen hfireplace hand hretain hthe hgeneral
happearance hof hthe hfireplace hwhile himproving hits hefficiency
Hearth happliance hconstruction h- hANSmodern hsolid hfuel happliance
hdesigned hto hintroduce hcombustion hair hthrough hspecific hand hcontrollable
hair hinlets hand hare hcontrolled hby hthe huser
Most hcontrolled hcombustion hdevices hare hmade hof h(metals) h- hANScast
hiron hor hsteel
Cast hIron h(fireplace) h- hANSmade hfrom hmolds, hcan hbe hdecorative
Steel h(fireplace) h- hANSwelded hjoints hthat hneed hno hservice, hsome huse
hsteel hfireboxes hinside hdecorative hcast hiron
Soapstone h(fireplace) h- hANSlower hthermal hconductivity, hdelivers hheat
hslowly hbut hretain hand hdelivers hheat hlonger
Conduction h- hANSdirect htransmission hof hheat hfrom hone hsurface hof
hsolid hmaterial hto hanother hsurface hof hsolid hmaterial
Convection h- hANStransfer hof hheat hthrough ha hgas hor hliquid, hincluding
hair, hthe htransfer hof hheated hair hbetween hareas hof hunequal hdensity.
hNatural hoccurs hbetween hheavier, hcooler hair hand hlighter, hwarmer hair
