Chapter 4 — Sequence of Operation
4-2 Part No. 750-184
A. GENERAL
Chapter 4 outlines the electrical sequencing of various controls through the
pre-purge, ignition, run, and shutdown cycles of the burner.
The program relay establishes the sequence of operation and directs the
operation of all other controls and components to provide an overall
operating sequence.
Note: The make or model of the program relay provided will
vary depending upon job specifications. The following
sequence applies regardless of the make or model. Please
refer to the Wiring Diagram (WD) prepared by Cleaver-
Brooks for your specific installation.
Abbreviations for the various electrical components are listed in Figure 4-1.
The sequences outlined in Chapter 4 employ specific nomenclature to aid in
applying the text to the wiring diagram.
The burner and control system are in starting condition when the following
conditions exist:
• Boiler water is up to the correct level, closing the low-water cutoff switch.
• 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 are below their cutoff setting.
• All applicable limits are correct for burner operation.
• The load demand light glows.
All entrance switches are closed and power is present at the line terminals
of:
• Blower motor starter
• Air compressor motor starter (if provided)
• Oil heater relay (if provided)
• Oil pump motor starter (if provided).
The sequences do not attempt to correlate the action of the fuel supply
system or feedwater system except for the interlock controls that directly
relate to the action of the program relay. Chapters 6 and 7 contain operating
instructions and specific information on setting and adjusting the controls.
B. CIRCUIT AND INTERLOCK CONTROLS
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 workable
system. The program relay provides connection points for the
interconnection of the various circuits.
The controls used vary depending upon the fuel oil or gas and the specific
requirement of applicable regulatory bodies. Refer to the boiler wiring
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