TYPICAL TEST LOCATIONS
Hot Water Heater
The flue probe must be inserted into the fire tube under the draft diverter. This
prevents the sample from being diluted. It may be necessary to drill a hole in the
diverter. The optional A797 flexible draft probe can be used to perform this test
without drilling a hole. Please refer to the figures below.
If necessary, drill a hole through the draft
diverter to enable the flue probe to be
inserted down into the fire tube. Cover the
hole when the test is complete. The
optional TPI flexible draft probe part num-
ber A797 can be used without drilling a
hole.
3. For testing in a flue, drill a 1/4 inch hole into the flue of the device under
test. 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 system.
This prevents room air from mixing with gases in the flue and diluting the
test sample.
Note:
If performing a test on a hot water heater insert the probe directly
down into the top of the water heater exhaust tube (fire tube). Measuring in
the gap between the hood and the exhaust pipe will not provide an accurate
reading due to dillution of the sample. Please see the figure on page
It is important to use manufacturers recommended test locations whenever
possible.
Refer to the figure below for calculating the sample hole location.
The figures on the following pages show typical test locations on commonly
encountered equipment.
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