Chapter 5 STARTING AND OPERATING INSTRUCTIONS
5-16 750-177
NOTE: Select the appropriate burner nozzle size curve based on the burner
size and capacity stamped on the burner nameplate (see Figure 5-8).
Input (MMBtu/hr.)
10. When the prepurge sequence ends, the pilot valve will
open. The pilot flame should be visible from the viewing
window.
11. When the pilot is established, the flame safeguard will
energize the main gas valve (this is accompanied by fuel
valve activity and illumination of the FUEL VALVE
light). The main gas valve should be visually checked by
observing the stem move from the CLOSED to the
OPEN position.
NOTE: The downstream manual gas shutoff
valve should be in the closed position, for
initial boiler startup, to ensure proper
operation of the automatic gas valves. This
valve can then be slowly opened when the
pilot is established and proven.
12. After the main flame has been established, the gas
pressure entering the burner should be read (using the
pressure tap between the butterfly valve and the blast
tube) to determine an initial estimate of the gas input rate.
By doing so, and referring to Figure 5-10, an
approximation of the burner input can be assessed.
Obtain a stable operating point by adjusting the butterfly
valve to the pressure indicated in Figure 5-10 and select
the temporary firing rate. This rate for startup is not
critical, but merely an acceptable starting point to begin
the high fire adjustment procedures.
13. After a few seconds, the O
2
analyzer should have an
accurate reading of the O
2
present in the flue gas. Table
5-1 provides a representation of the acceptable O
2
range
for the gas burner. Normally, the O
2
levels are set
between 3 and 5 percent at low fire, depending on the
application and burner size (see the burner specification
plate for the minimum firing rate).
14. Operate the boiler at low fire until it is thoroughly
warmed. Then increase the fuel input to the boiler by
turning the manual flame potentiometer towards open in
Figure 5-13: Burner Input vs. Oil Pressure and Nozzle Size (Size #2 Burners)
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