Watts Benchmark Aerco OMM-0122 - Page 64

Benchmark 750-3000 Boiler Installation & Startup Manual
SECTION 4 – INITIAL START-UP
OMM-0121_D • GF-205 • 5/9/2019 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 64 of 122
NATURAL GAS Combustion Calibration Instructions
15. On Benchmark 3000 units only, once the manifold gas pressure is within the range in
table 4-1, record this value; it will be used later, in Section 5.2.2: Low Pressure Gas Test,
and Section 5.3.2: High Pressure Gas Test.
16. Press the Down▼ arrow key until SET Valve Position appears on the display, then press
CHANGE.
17. Press the Up ▲ arrow key until the SET Valve Position reads 100%, then press ENTER.
18. With the valve position at 100%, insert the combustion analyzer probe into the exhaust
manifold probe opening (see Figure 4-2a or 4-2b in Section 4.2.3) and allow enough time
for the combustion analyzer reading to stabilize.
19. Compare the combustion analyzer’s oxygen readings to the O
2
Sensor value displayed in
the Operating menu on the C-More Controller. The offset value in the Calibration menu can
be adjusted by ±3% to make the on-board O
2
sensor match the value from the combustion
analyzer. If the values differ by more than ±3% and your combustion analyzer is correctly
calibrated, the on-board O
2
sensor may be defective and need to be replaced.
20. Compare the measured oxygen level to the oxygen range shown in Table 4-2. Also, ensure
that the nitrogen oxide (NO
x
) and carbon monoxide (CO) readings do not exceed the
values shown in Table 4-2. If your target NO
x
value is 9 ppm or less, use the values in the
Ultra-Low NO
x
columns. If you are not in a “NO
x
-limited” area and/or do not have a NO
x
measurement in your analyzer, set the oxygen (O
2
) at 5.5% ± 0.5%.
TABLE 4-2: NATURAL GAS Calibration Readings 100% Valve Position
Model
Standard NO
x
Ultra-Low NO
x
Carbon
Monoxide (CO)
Oxygen (O
2
)
%
Nitrogen
Oxide (NO
x
)
Oxygen (O
2
)
%
Nitrogen
Oxide (NO
x
)
750 5.5% ± 0.2% ≤20 ppm 6.0% ± 1.0% ≤9 ppm <100 ppm
1000
5.5% ± 0.2%
≤20 ppm
6.0% ± 1.0%
≤9 ppm
<100 ppm
1500 5.2% ± 0.2% ≤20 ppm 5.7% ± 1.0% ≤9 ppm <100 ppm
2000 6.0% ± 0.2% ≤20 ppm 6.0% ± 1.0% ≤9 ppm <100 ppm
2500 5.6% ± 0.2% ≤20 ppm - - <100 ppm
3000 5.1% ± 0.2% ≤20 ppm - - <100 ppm
3000 DF 5.3% ± 0.2% ≤20 ppm - - <100 ppm
21. Next, press the Down ▼ arrow key until CAL Voltage 100% is displayed.
22. Press the CHANGE key and observe that CAL Voltage 100% is flashing.
23. The oxygen level at the 100% valve position should match the value in Table 4-2. Also,
ensure that the NO
x
and CO readings do not exceed the values in Table 4-2.
24. 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 Up ▲ arrow key increases the oxygen level and pressing the down
▼ arrow key decreases the oxygen level.
25. Once the oxygen level is within the specified range at 100%, press the ENTER key to store
the selected blower output voltage for the 100% valve position. Record all readings on the
Combustion Calibration Sheets provided.