750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
5-9
5.6 — Firing Preparation for No. 6 Oil (Series 400-600)
Final regulation of oil flow to the nozzle can be done, if necessary, by adjusting the metering cam screws as outlined
in Chapter 6.
5.6.3 — Oil Temperature
After determining that the heater shell is filled and that fuel oil circulation exists, turn the oil heater switch to “on.”
Adjust the electric oil heater thermostat to maintain oil temperature at approximately 200º F.
The electric heater on burners equipped for No. 6 fuel oil is sized so that it
is capable of supplying heated oil at a rate no greater than that required for
low-fire operation and is primarily supplied for convenience on cold starts.
Heating coils utilizing either steam or hot water are supplied to provide
sufficient heat so that higher rates of firing can be accomplished once
steam or hot water is available. In normal operation, the thermostat gov-
erning the electric heating element is kept at a lower setting than the ther-
mostat governing admission of steam to the heater, or of hot water, so
that heating is not performed electrically except when steam or hot water
is not available.
FIGURE 5-10. Electric Module (Heavy Oil Heater)
Set the steam thermostat or the hot water thermostat to maintain an oil temperature of 220º - 230º F. The electric
heater will be turned off as soon as steam or hot water provides heat.
Close the manual bypass valve after the temperature rise on the fuel oil controller thermometer is noted. Be certain
that hot oil is moving through the controller. The orifice gate valve must also be closed. If the temperature drops,
open the orifice gate valve until a rise is noted, then close it.
Once the correct setting of the heater thermostats has been established, set the low oil temperature switch at
approximately 30º F lower than the normal burning temperature. If the system is equipped with a high oil tempera-
ture switch, it should be set to open at 20º - 30º F higher than normal burning temperature.
When all the conditions covered above and in Sections 5.1, 5.2, 5.3, and 5.4 are assured, the burner is ready for fir-
ing. Refer to Section 5.8 for further starting and operating information.
Before turning on the electric oil heater switch, be certain that the heater shell is filled with fuel oil and the flow is
established. Failure to follow these instructions could result in equipment damage.
NOTE: The temperatures listed are tentative. The composition of the fuel oil in a given grade can vary, necessitating a
higher or lower preheating temperature. The viscosity of the oil at the nozzle should be between 55 and 100 SSU,
approximately. The actual temperature of the oil at the burner should be determined by flame appearance and good
combustion based on a stack analysis.
!
Caution
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