AERCO BMK 6000 - Manual (Page 55)

Benchmark 6000 Boiler Installation, Operation & Maintenance Manual
CHAPTER 3 – OPERATION
OMM-0086_0D AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 55 of 210
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03/20/14
3.11 START/STOP LEVELS
The start and stop levels are the Air/Fuel Valve positions (% open) that start and stop the unit,
based on load. These levels are Factory preset as follows:
Start Level: 22%
Stop Level: 18%
Normally, these settings should not require adjustment.
Note that the energy input of the boiler is not linearly related to the Air/Fuel Valve position. Refer
to Table 3-8 and the chart in Figure 3-8 for the relationship between the energy input and
Air/Fuel Valve position for a BMK 6000 MBH boiler running on natural gas.
The boiler has a downstream low pressure gas switch that will shut down the boiler when the gas
pressure drops below 7” W.C. See Table 3-9.
Table 3-8: Relationship Between Air/Fuel Valve Position and Energy Input
For 6000 MBH Unit Running On Natural Gas
Air Fuel Valve Position
(% Full Open)
Boiler Energy Input Turndown
Ratio
BTU/Hr
(% of Full
Capacity)
0% 0 0 0.0
10% 0 0 0.0
18% (Stop Level) 385,000 6 15.6
20% 400,000 7 15.0
30% 540,000 9 11.1
40% 770,000 13 7.8
50% 1,160,000 19 5.2
60% 1,650,000 28 3.6
70% 2,386,000 40 2.5
80% 3,515,000 59 1.7
90% 4,650,000 78 1.3
100% 6,000,000 100 1.0