750-392
CBEX-DE
4-1
CHAPTER 4 Startup and Operation
4.1 — Sequence of Operation
On a combination fuel unit, the gas/oil switch must be set for the proper fuel.
The burner and control system are in starting position when the following conditions are met:
• Boiler water is up to the correct level, closing the low-water cutoff switch, and the auxiliary low water cutoff,
if applied.
• The low-water light (panel) is off.
• The operating limit pressure control (steam boiler) or the operating limit temperature control (hot water boiler)
and high limit pressure or temperature control switches are closed.
• All other limit circuit switches are closed.
• All entrance panel switches are closed and power is present at the line terminals corresponding to:
a. Blower motor starter.
b. Air compressor motor starter (if provided).
c. Oil pump motor starter (if provided).
• The load demand light is on.
Circuits and Interlocks:
The burner control circuit is a two-wire system designed for 115 VAC, 60 Hz, single-phase power.
The electrical portion of the boiler is made up of individual circuits with controls that are wired in a manner
designed to provide a safe system.
NOTE: The intent of this section is to provide a general overview of a typical boiler operating sequence. Specific con-
trol circuit components/interlocks, and control system hardware and programming may vary depending on installa-
tion. Please refer to the wiring diagram prepared by Cleaver-Brooks for your specific installation.
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