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Carbon Monoxide Analysis Overview

Performing carbon monoxide analysis is very important to the overall safety
of heating equipment and appliances. The following guidelines and descrip-
tions are generic and meant to provide you with a basic understanding of
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.

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. This may take more than an hour depending on how saturated the
sensor is.

The figures on pages 15 through 18 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.

NOTE: Your 707 carbon monoxide analyzer is equipped with a high
quality sensor that incorporates an on-board NO/NOx filter. This fil-
ter prevents higher than normal CO readings caused by sensor
cross sensitivity to NO/NOx, which is a byproduct of combustion.

When a gas appliance or hot water heater is operating properly, lit-
tle or no CO will be produced. Older CO analyzers, and those
equipped with sensors that do not have an on-board filter, will
incorrectly read higher levels of CO because of the “NOx bump” or
cross sensitivity to the NO/NOx present in the sample.

The NO/NOx cross sensitivity can increase the displayed reading
by as much as 30ppm or more on analyzers with sensors that do
not have the NO/NOx filter.

Testing for Carbon Monoxide in Ambient Air

Note: It is recommended you perform routine general maintenance on your
analyzer to ensure proper function. Please refer to Appendix A for general
maintenance schedule and function tests.

1. Turn the 707 on in fresh air as outlined on page 8. After the initial purge cycle
the 707 will display the screen below.

2. After the purge cycle is complete the carbon monoxide level will be seen.
Please see below.

•

Carbon Monoxide Display (Real Time)

• Displays Carbon Monoxide (CO) reading in parts per mil-
lion (ppm)

3. Connect the Mini Pump Protection filter to the analyzer. See picture below.

4. Begin testing for carbon monoxide. Move from space to space to detect any
CO that may be present. The CO reading will be seen in the top part of the dis-
play.

5. If necessary, the flue probe can be attached to test in ducts and plenums.

6. Refer to the chart on the next page for a list of exposure times and levels of
carbon monoxide in ambient test applications.

7. If necessary, the Scroll/Enter key can be pressed to display the peak CO mea-
sured since the 707 was turned on. Pressing and holding down the Down Arrow
key will zero the peak reading. Pressing the Scroll/Emter key again will return
the 707 to normal operation.

8. When testing is complete, turn the analyzer off as outlined on page 9.