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 712. The default function is Combustion Analyzer. Other available func-
tions are: Thermometer, Manometer/Tightness Test, Combustible Gas Leak
Detector, and Date / Time display.
Refer to the Appendix G “Technical Notes” for additional information.
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Turning The Analyzer Off
Always: - Before turning off return the instrument to a clean air environment
and allow the Carbon Monoxide level to return to below 15ppm and the
Oxygen level to return to 20.9% (± 0.3%) Press the Power Key to turn the
instrument off:- NOTE Should you attempt to turn the instrument Off and the
CO reading is above 15ppm then the instrument will remain On and a short
Beep will be heard. The Instrument can only be switched off if the CO is
below 15ppm
The instrument has an auto shut off after 10 minutes should no keys have
been pressed for this period and as mentioned above that the CO is below
15ppm. Should the CO be above 15ppm then the 10 minute auto shut off
countdown will not begin till the CO has gone below 15ppm. The auto power
off feature can be disabled. Please see Appendix D. The auto power off fea-
ture is always enabled upon power up.
Activating the Backlight
The display backlight can be activated at any time by pressing and holding
down the Func Key for approximately 2 seconds. The backlight will automati-
cally shut off after approximately 20 seconds to preserve battery life.
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