Manual

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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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