AERCO BMK 6000 - Manual (Page 62)

Benchmark 6000 Boiler Installation, Operation & Maintenance Manual
CHAPTER 4 – INITIAL START-UP
Page 62 of 210 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 OMM-0086_0D
03/20/14
Ph.: 800-526-0288
GF-133
4.3 PILOT IGNITION
The Boiler is equipped with an interrupted pilot ignition system. The pilot is ignited by a spark
discharge within the Pilot Burner inside the combustion chamber. The input of the Pilot flame is
approximately 18,000 BTU/hr. The Pilot Burner flame will stay ignited until the main Burner flame
has stabilized and “Flame Proven” appears in the C-More Controller display.
A Pilot gas supply regulator reduces the supply pressure from line pressure to 4.9” W.C. An
orifice (0.073” dia.) further restricts the gas flow to the Pilot in accordance with UL safety test
requirements.
The Pilot Burner should be inspected at the beginning of each heating season, or every 6
months for continuous operation units. It is constructed of high quality, heat resistant stainless
steel materials, however some darkening of the metal is to be expected. No adjustment of the
Pilot should be required, however the gas pressure downstream of the regulator should be
checked if an ignition issue is encountered. Refer to Figure 4-1 for test port location.
The Pilot flame is proven by the AERCO BST Sensors located above and below the Pilot. The
boiler has two Pilot Flame Detectors. The AERCO BST is an optical sensor inserted in a
viewport. The sensor has a red LED which changes from flashing to steady- ON when the sensor
encounters the flicker of a flame that meets or exceeds the internal sensing threshold. The
sensor is inserted into a tube with a quartz window and observes the Pilot through a hole in the
refractory. The hole in the refractory should be checked annually to ensure that the optical path
to the Pilot Burner is clear.
NOTE
The AERCO BST sensor switches the signal to neutral when the
flame is proven.
4.4 NATURAL GAS COMBUSTION CALIBRATION
NOTE
When installed and operated in accordance with the requirements
specified in this section, the Benchmark 6000 boiler delivers low
NOx emissions of <20 ppm at all firing rates. Alternatively, these
boilers can be combustion calibrated to provide Ultra-low NOx
emissions of <9 ppm.
To combustion calibrate the boiler to produce low NOx emissions
of <20 ppm, complete the instructions in this section. To
combustion calibrate the boiler to produce ultra-low NOx
emissions of <9 ppm, first complete the instructions in this section
and then, in addition, complete the instructions in Appendix N.
The Benchmark 6000 boiler is combustion calibrated at the factory prior to shipping. The gas
pressure, measured at 100% fire rate (Air/Fuel Valve % open position) on the downstream side
of the SSOV, must be within the range of 7.9” W.C. ±0.4” W.C. Recalibration as part of initial
start-up is necessary due to changes in the local altitude, gas BTU content, gas supply piping
and supply regulators. Combustion Calibration Test Data sheets are shipped with each unit.
These sheets must be filled out and returned to AERCO for proper Warranty Validation.