Benchmark 1500 - 2000 Boilers
CHAPTER 4 – INITIAL START-UP
Page 58 of 182 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 OMM-0097_0E
10/01/2015 Ph.: 800-526-0288 GF-142
BMK 1500 Natural Gas Combustion Calibration – Continued
25. The oxygen level at the 70% valve position should be as shown below. Also, ensure that
the nitrogen oxide (NOx) and carbon monoxide (CO) readings do not exceed the
following values:
Table 4-3: Combustion Calibration Readings – 70% Valve Position
Valve Position Oxygen (O
2
) % Nitrogen Oxide (NOx) Carbon Monoxide (CO)
70% 5.9% ± 0.5% ≤20 ppm <100 ppm
26. If the oxygen level is not within the specified range, adjust the level using the ▲ and ▼
arrow keys. This will adjust the output voltage to the blower motor as indicated on the
display. Pressing the ▲ arrow key increases the oxygen level and pressing the down ▼
arrow key decreases the oxygen level.
27. Once the oxygen level is within the specified range at 70%, press the ENTER key to
store the selected blower output voltage for the 70% valve position. Record all readings
on the Combustion Calibration Sheets provided.
28. Repeat steps 20 through 27 for valve positions of 50%, 40%, 30% and 16%. The oxygen
(O
2
), nitrogen oxide (NOx) and carbon monoxide (CO) should remain within the same
limits for all valve positions as shown in the following table.
NOTE
If NOx readings exceed the target values shown (<20 ppm),
increase the O
2
level up to 1% higher than the listed calibration
range shown in the table. Record the increased O
2
value on the
Combustion Calibration sheet.
Table 4-4: Combustion Calibration Readings
Valve Position Oxygen (O
2
) % Nitrogen Oxide (NOx) Carbon Monoxide (CO)
50% 6.0% ± 0.5 <20 ppm <100 ppm
40% 6.3% ± 0.5 <20 ppm <100 ppm
30% 6.3% ± 0.5 <20 ppm <100 ppm
16% 6.0% ± 0.5 <20 ppm <100 ppm
29. If the oxygen level at the 16% valve position is too high and the Blower voltage is at the
minimum value, you can adjust the idle screw (TAC valve) which is recessed in the top of
the Air/Fuel Valve (see Figure 4-4). Rotate the screw 1/2 turn clockwise (CW) to add fuel
and reduce the O
2
to the specified level. Recalibration MUST be performed again from
60% down to 16% after making a change to the idle screw (TAC valve).
30. This completes the BMK 1500 Natural Gas combustion calibration procedures.
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