Burner Operation and Control
2-2
750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
Safety interlock controls include combustion and atomizing air proving switches and, depending upon the fuel and
insurance carrier requirements, controls that prove the presence of adequate fuel pressure, plus temperature prov-
ing controls when heated fuel oil is used.
The sequence of burner operation from startup through shutdown is governed by the program relay in conjunction
with the operating, limit, and interlock devices. The devices are wired into the circuitry to provide safe operation
and protect against incorrect operating techniques.
All Promethean 4WI boilers have the burner assembly integral
with the front head. The entire head may be swung open for
inspection and maintenance.
Combustion air is provided by a centrifugal blower located in
the front head. Combustion air delivery to the burner is under
the control of the damper motor. The motor also regulates the
flow of fuel through a linkage system connected to the gas but-
terfly valve and/or oil through a cam-operated metering valve.
Fuel input and air are thus properly proportioned for most effi-
cient combustion.
FIGURE 2-2. Open Front Head
2.2 — Controls Common to all Boilers
Filtered primary air for atomizing fuel oil is furnished independently of combustion air by an air pump. The burner
control circuit operates on 115 volt, single-phase 60 Hz (or 50 Hz when equipped) alternating current. The forced
draft fan motor is generally operated on 3-phase service at the available main power supply voltage.
Indicator lights signaling load demand, fuel valve, low water, and flame failure conditions are standard equipment.
FIGURE 2-3. Control Panel Indicator Lights
In addition to the standard basic controls supplied, other devices may be required to meet specific requirements of
an insurance carrier or local code. Refer to the Wiring Diagram (WD) prepared by Cleaver-Brooks for the installa-
tion to determine the specific controls in the burner and limit control circuits. The function of individual compo-
nents is outlined in this chapter and the electrical sequence is covered in Chapter 4.
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