Uei-test-instruments C127OILKIT Manuel d'utilisateur télécharger pdf (Page 17)

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iNformatioN oN exCeSS air

 •ExcessAir

- Theoretically perfect combustion would have the exact amount of O2 to combine with all of the fuel,

resulting in no excess air.

   •Ifperfectcombustionwerepossible,therewouldbe0%excessair

   •Becauseperfectcombustionisnotpossible,youwillalwayshavesomeexcessair

   •Toohighexcessairwillreducethetimefuelandoxygenaretogetherinthecombustion

   chamber,andlowerthetemperature–twooftheT’sofcombustion

   •Toolittleexcessair,andallofthefuelwillnotbeburnt

- Carbon will form CO instead of CO2

 •TypicalExcessAirLevel

O2% (measured) Excess Air %

  Naturalgas 3% 16.7%

  LightOil 5% 31%

  Coal 8% 62%

 ExcessAirisalsoonemethodthatcanbeusedtodetermineheatexchangerintegrity

 •Beforetheblowerstartsthepressureishigheronthecombustionsideofexchange(seefigure5)

  –SmallamountsofCOmayleakintothelivingspaceside

  –Fluegasmeasurementswillbestabilizingasthecombustionchamberheatsup.

 •Aftertheblowerstartsthepressureontheprimarysidewillbehigher(Seefigure6)

  –Blowerforcingairthroughtheheatsystem

  –Freshairmaynowenterthefluethroughthebreachintheheatexchange

 •Observethefluegaslevelsandcheckthefollowing;

  -ExcessAir,02levelandCOinppmfordrasticchanges.

figure 6

figure 5

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Uei-test-instruments C127OILKIT Manuel d'utilisateur Page 17