Benchmark 6000 Boiler Installation, Operation & Maintenance Manual
APPENDIX N – ULTRA-LOW NOX CALIBRATION
Page
208
of
210
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
OMM-0086_0D
03/20/14
Ph.: 800-526-0288
GF-133
Ultra-Low NOx Natural Gas Combustion Calibration -
Continued
NOTE
If NOx readings exceed the target values shown (<9 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.
Ultra-Low NOx
Combustion Calibration Readings
Valve Position
Oxygen (O
2
) %
Nitrogen Oxide (NOx)
Carbon Monoxide (CO)
60%
5% - 7%
<9 ppm
<100 ppm
45%
5% - 7%
<9 ppm
<100 ppm
30%
5% - 7%
<9 ppm
<100 ppm
18%
5% - 7%
<9 ppm
<100 ppm
29. If the oxygen level at the 18% 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 Appendix F). 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 18% after making a change to the idle screw (TAC valve).
30. This completes the ultra-low NOx Natural Gas combustion calibration procedures.
N-2. REASSEMBLY
Once the combustion calibration adjustments are properly set, the unit can be reassembled for
service operation.
Reassembly
1. Set the
ON/OFF
switch to 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.
