# Strange Results



## uaplumber (Mar 22, 2009)

One of my guys did a combustion test and found the oxygen levels rose in the heat exchanger to 24.6 ppm. I am going to change the batteries and try again but, is there any reason for it to rise?


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## DuMass (Jul 7, 2009)

uaplumber said:


> One of my guys did a combustion test and found the oxygen levels rose in the heat exchanger to 24.6 ppm. I am going to change the batteries and try again but, is there any reason for it to rise?


I'm just wondering if the tech is sure he wasn't reading CO or CO air free ppm?
O2, CO2 and excess air are usually indicated as a percentage [%], not ppm.

If not, the only thing I can think of as to why it might climb to over 20.9 % would maybe be if the O2 sensor were out of calibration.

Coincidentally, the O2 sensor on my own Bacharach analyzer is now completely dead for the second time in two years. I’ve tried field recalibrating it as per the manual, but it is a lost cause, so it looks like it’s off to the service center… once again. That is… I guess… as long as I can continue to resist the overwhelming urge to smash the frigging thing to pieces with my 4-pound drilling hammer. :001_unsure:


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## beenthere (May 30, 2009)

What did you find out.
Was he looking at the % of excess air by mistake?


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