COMBUSTION ANALYSIS OVERVIEW
Performing combustion analysis is very important to the overall safety and
efficiency of heating equipment. The following guidelines and descriptions are
generic and meant to provide you with a basic understanding of combustion
testing. TPI always recommends you contact the manufacturer of the device
under test, obtain information specific to the device, and follow the proce-
dures and safety guidelines for performing tests and affecting repairs.
In general, for most applications, flue gas samples should be taken prior to
the draft diverter or any other opening that allows room air to enter the sys-
tem. This prevents room air from mixing with gases in the flue and diluting
the test sample. To ensure accurate and consistent combustion tests, it is
important gas and temperature samples be taken at the same location. This is
easy with the TPI flue probe because the temperature sensor is an integral
part of the probe.
Prior to taking a sample, the device under test should be on and operating.
Putting the flue probe in the sample area prior to starting the device may
cause saturation of the sensors due to the higher initial concentration of car-
bon monoxide that may be encountered upon start up. If this happens, allow
your analyzer to purge in fresh air until the carbon monoxide level returns to
0 ppm and the oxygen level returns to 20.9%. This may take more than an
hour depending on how saturated the sensors are.
The figures on pages 13 through 15 show locations for performing tests on
commonly encountered equipment. Remember to consult with the manufac-
turer of the device under test for specific test information.
Pressing the Func Key enables access to the different functions available on
the 717. The default function is Combustion Analyzer. Other available func-
tions are: Thermometer, Manometer/Tightness Test, and Date / Time display.
Refer to the Appendix G “Technical Notes” for additional information.
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