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combustion test

George J.
George J. Member Posts: 25
I recently got a call for a pilot that wouldn't stay lit.  When I got there.  The boiler was completely pluggd up with soot.  I brushed down the flue passages.  Replaced the burner tubes because they had big holes rusted in them.  Also the gas valve needed to be replaced.  When I finished everything I did a combustion test.  Co was 30 o2 was between 6 and 7 percent but the stack temp kept going up eventually  getting to 650.  I have never gotten a stack temp this high.  Seems like it would be overfired but if I lower it the o2 reading goes why down.  Could it be my meter is not working right?  It is brand new and I have only used it maybe 4 times.  The boiler is an old Utica HW maybe 15-20 years old. 


  • Tim McElwain
    Tim McElwain Member Posts: 4,629
    I am assuming that

    stack temp was already minus room temp.

    Do you know how to clock a burner using the test dial on the gas meter?

    Do you know what the outlet gas pressure was on your new gas valve you installed?

    What is the input to the boiler taken from the rating plate?

    Normal readings on a design gas equipment is between 5% to 7% O2

    CO2 - 9.5 to 10.5%, CO Air Free should be under 100 PPM, stack temp 350°F to 550° F.

    What was your draft reading?
  • George J.
    George J. Member Posts: 25

    I know how to clock the meter.  I don't remember the input.  I think it was around 80000.  I didn't check the outlet gas pressure.  The draft was .01
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