Cleaver-Brooks CBH 40 - Page 12

Chapter 1-General Description and Principles of Operation
It also operates, through linkage, the butterfly gas
valve.
A modulating motor can be supplied as optional
equipment on a gas fired unit. (Figure 1-2) See Sec-
tion G for details.
DAMPER POSITIONING SWITCH
(Manual-Automatic) (Figure 1-1)
A three-position switch for manually setting either
high fire or low fire rate or establishing a circuit
through the high-low fire control for automatic
operation.
AUXILIARY SWITCH(S) (Figure 1-1)
Actuated by damper motor shaft rotation. Each
boiler has a switch that serves as a low fire switch
to prove that the damper is in a closed position
before ignition can take place. An oil fired boiler
has additional switches that control oil solenoid
valves for high fire operation. An optionally equip-
ped boiler has an additional switch to prove dam-
per opening during the pre-purge.
GAS/OIL SWITCH (Figure 1-1)
Toggle switch used to manually select circuitry for
either gas or oil firing.
IGNITION TRANSFORMER (Figure 1-1)
Provides high voltage spark for ignition electrode
of gas pilot or light oil burner ignition.
OPERATING PRESSURE,
HIGH PRESSURE. AND
M lNG
DAMPER
MOTOR
(OPTIONAL FOR
GAS FIRING)
1-4
HIGH-LOW FIRE CONTROLS
MODULATING
CONTROL
(OPTIONAL FOR
GAS FIRING)
CHECK
VALVE
FIGURE 1-2 TYPICAL STEAM BOILER AND CONTROLS
GAGE
GLASS