42
Figure 10.2: Gas Valve Detail
11)Performacombustiontest.Onhorizontallyventedunits,thesampleprobemaybeinsertedintotheterminal.
Ifthisisnotpossible,andifnosampletapispresentintheventsystem,removetheuetemperaturesensor
andinserttheanalyzerprobeinthesensoropening.OntheCHG150andCHG225theuetemperatureprobe
islocatedbehindthelowervestibuledoor.Fortheboilertooperate,thissensorwillneedtobetemporarily
connectedoutsideoftheboiler.Ifitisremoved,besuretoreturntheuegastemperaturesensortoitsoriginal
positionaftercombustiontestingiscomplete.
 CheckCO2(orO2)andCOatbothhighandlowre.Theboilermaybetemporarilylockedintohighorlow
refor15minutesasfollows:
a) Tolocktheboilerinhighre,simultaneouslypressandholdthe“Mode”buttonand“+“buttonuntil
thedisplayashes“H”,indicatingthattheboilerhasbeendriventohighre.Afterthishappens,allowthe
boilertooperateforapproximately5minutesbeforetakingcombustionreadings.
b) Tolocktheboilerinlowre,simultaneouslypressandholdthe“Mode”buttonand“-“buttonuntil
thedisplayashes“L”,indicatingthattheboilerhasbeendriventolowre.Afterthishappens,allow
theboilertooperateforapproximately5minutesbeforetakingcombustionreadings.
 Atbothhighandlowre,COreadingsshouldbelessthan75PPM.TypicalCO2readingsareshowninTable
10.3.
 Normalmodulationoftheboilershouldreturn15minutesaftertheboilerislockedinhighorlowre.
Table 10.3: Typical CO2/O2 Combustion readings range
Model Fuel %CO2 %O2
CHG150 Natural Gas 8.2 6.3
CHG225 Natural Gas 8.7 5.4
CHG150 Propane NA NA
CHG225 Propane 10.2 5.4
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