Benchmark 2500 - 3000 Boilers
CHAPTER 4 – INITIAL START-UP
Page
62
of
207
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
OMM-0094_0F
09/30/2015
Ph.: 800-526-0288
GF-137
BMK 3000 Natural Gas Combustion Calibration
–
Continued
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 4-7:
Combustion Calibration Readings
Valve Position
Oxygen (O
2
) %
Nitrogen Oxide (NOx)
Carbon Monoxide (CO)
50%
5.5%
-
6.5
<20 ppm
<100 ppm
40%
4.5%
-
5.5
<20 ppm
<100 ppm
30%
6.0%
-
6.5
<20 ppm
<100 ppm
14%
6.0%
-
7.0
<20 ppm
<100 ppm
29. If the oxygen level at the 14% 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 4-5). 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
50% down to 14% after making a change to the idle screw (TAC valve).
30.
This completes the BMK 3000 Natural Gas combustion calibration procedure.
4.4 REASSEMBLY
Once the combustion calibration adjustments are properly set, the unit can be reassembled for
service operation.
Reassembly
1. Set the ON/OFF switch in the
OFF
position.
2. Disconnect AC power from the unit.
3. Shut off the gas supply to the unit.
4. Remove the manometer and barbed fittings and reinstall the NPT plug using a suitable
pipe thread compound.
5. Remove the combustion analyzer probe from the 1/4” vent hole in the exhaust manifold.
Replace the 1/4” NPT plug in the manifold.
6. Replace all previously removed sheet metal enclosures on the unit.
7.
This concludes reassembly of the unit after combustion calibration.
