MODEL 300 COMBUSTION ANALYZER
3-6 Instruction 24-9223
3.2 GAS SAMPLING POINTS
The Model 300 Combustion Analyzer requires a
3
/
8
" (9.5 mm) minimum
diameter sampling hole to accommodate the analyzer’s probe-stop.
Locate the sampling point downstream from the last heat exchanger, and
upstream from any source of dilution.
Important: As the distance between
the heat exchanger and the sampling
point increases, the calculated combus-
tion efficiency will falsely increase due
to heat loss in the flue or stack.
For residential and light commercial
combustion equipment applications, the
following recommendations are applicable:
• Oil Burners – Locate sampling hole at
least 12" downstream from the furnace
breeching, and at least 6" upstream from
the furnace side of the draft regulator.
• Gas Burners – Locate sampling hole at
least 6" upstream from the furnace side
of the draft diverter on gas conversion
units. For gas-designed equipment, the
probe may be inserted down into the flue
through the draft diverter or hood.
3.3 INSTALLING THE PROBE
Screw probe stop into gas-sampling hole (Fig. 3-3); then insert probe
through hole in probe stop.
Push probe into stack to desired depth; then tighten probe-stop-thumb
screw to lock probe in place.
Figure 3-2.
Sample Point
DRAFT
DIVERTER/
REGULATOR
SAM PLE
POINT
FURNACE
BREECHING
FLUE GAS FLOW
(U p s tre a m )
(D ow nstream )
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