Adjustment Procedures
6-24
750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
6.21.1 — Standard Burner Low-Fire Adjustment 100-200 HP
The fuel input should be adjusted with the low-fire cam screw to approximately 25% of that at high-fire. At low fire
the O
2
flue gas reading should be between 5% and 7%.
6.21.2 — Burner Low-Fire Adjustment 250-800 HP
Fuel input at low-fire should be approximately 12.5% of that at high-fire. The low-fire screw should be adjusted to
obtain the necessary input for the fuel turndown required. At low-fire the O
2
flue gas reading should be between
5% and 7%. The second cam adjusting screw may need to be adjusted in order to maintain a smooth cam profile.
6.22 — Burner Drawer Adjustment
There are relatively few adjustments that can be made to the burner, however,
a check should be made to assure that all components are properly located,
and that all holding screws are properly tightened.
The diffuser location on gas fired boilers is important. There should be 1/4”
distance between the edges of the diffuser fins and gas outlet tubes (spuds)
coming from the burner housing. The setting of an oil fired burner is less
exacting and the diffuser should be located with the diffuser skirt approxi-
mately 1-1/8” in front of the oil nozzle.
When the proper diffuser location is ascertained, the setting of the nozzle in
relation to the diffuser should be checked. This generally is set at time of man-
ufacture and seldom needs altering. It is most important that oil spray does
not impinge upon the diffuser. The distance that the nozzle is behind the dif-
fuser has some latitude, and individual installation may require a slight devia-
tion.
FIGURE 6-18. Burner Drawer in Burner Housing
Check the setting of the ignition electrode(s) for proper gap and position. See Figure 6-19 for the gas pilot elec-
trode and Figure 6-20 for the light oil pilot. Be sure that the porcelain insulator is not cracked and that ignition
cable connections are tight.
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