Benchmark 5000 & 6000 Pilot Flame Ignition; Fuel Types And Combustion Calibration; Combustion Calibration - Watts AERCO Benchmark BMK5000 Operation And Service Manual

Benchmark Platinum-Edge [ii]: Operation-Service Manual
SECTION 4 – INITIAL START-UP
4.3 BENCHMARK 5000 & 6000 PILOT FLAME IGNITION
Benchmark 5000 and 6000 boilers are 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. (5.3 kW). The Pilot Burner flame will stay
ignited until the main Burner flame has stabilized and FLAME PROVEN appears on the
Controller's display.
The Pilot gas supply regulator reduces the supply pressure as follows:
•
On standard pressure models, it reduces line pressure to 4.9" W.C. (1.2 kPa).
•
On Low Gas Pressure models, it reduces line pressure to 2.0" W.C. (0.5 kPa).
The Pilot Burner should be inspected at the beginning of each heating season, or every 6 months
of continuous operation. It is constructed of high quality, heat resistant stainless steel, however
some darkening of the metal is 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 Burner flame is proven by two Pilot Flame Detectors, located above and below the Pilot
Burner. These are optical sensors inserted into tubes with quartz windows; they observe the Pilot
through holes in the refractory insulation. They have a red LED which changes from flashing to
steady-ON when they encounter the flicker of a flame that meets or exceeds the internal sensing
threshold. (Only one of the two detectors need to sense the pilot flame throughout the ignition
period). The holes in the refractory should be checked annually to ensure that the path to the
Injector-Ignitor is clear.
NOTE:
The Pilot Flame Detectors switch the signal to neutral when the flame is proven.

4.4 FUEL TYPES AND COMBUSTION CALIBRATION

All BMK Platinum models are preconfigured at the factory to use either natural gas or propane
gas, and BMK models 1500 to 6000 are available in dual fuel versions (natural gas and
propane).
Both fuel types require different combustion calibration values, and so care must be taken to
ensure to follow the instructions for the fuel being used.
•
Natural Gas combustion calibration: Section 4.4.1
•
Propane combustion calibration: Section 4.4.2
Instructions for switching between fuel types in dual fuel models are presented in Section 4.6.

4.5 COMBUSTION CALIBRATION

The Benchmark boiler is combustion calibrated for Standard NOx emissions (<20 ppm). For
jurisdictions that require Ultra-Low NOx operation (<9 ppm), see Table 4-2 for details. The gas
pressure must be within the ranges shown in Table 4-2 for each model of boiler at full fire.
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.
OMM-0137_J •
12/20/2022
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