General Description
1-2
750-96 (revised 2010)
Model CB Packaged Boiler Manual
The horsepower rating of the boiler is indicated by the numbers following the fuel series. Thus, CB700-60 indi-
cates a gas-fired 60 HP boiler.
1.3 — Burner and Control System
The oil burner is of the low pressure, air atomizing (nozzle) type. The gas burner is of the non-premix orifice type.
The burners are ignited by a spark-ignited gas pilot. The pilot is of the interrupted type and is extinguished after
the main flame is established.
The burners equipped to burn oil and gas include equipment for each distinct fuel. Since the burner uses only
one type of fuel at a time, a gas/oil selector switch is incorporated in a combination burner.
It is important that the burner model and serial number, shown on the nameplate, be included in any correspon-
dence or parts ordered.
Regardless of which fuel is used, the burner operates with full modulation (within its rated operating range)
through potentiometer-type positioning controls, and the burner returns to minimum firing position for ignition.
High pressure boilers (above 15 psi) can be wired for both low pressure and high pressure modulation as
optional equipment. This enables the boiler to operate at lower pressure during off-load hours, but at a some-
what reduced steam output dependent upon lower steam pressure and steam nozzle sizing.
The flame safeguard and program relay includes an infrared sensitive flame detector to supervise both oil and
gas flames and to shut the burner down in the event of loss of flame signal. The programming portion of the con-
trol provides a pre-purging period, proving of the pilot and main flame, and a period of continued blower opera-
tion to purge boiler of all unburned fuel vapor. Other safety controls shut down the burner under low water
conditions, excess steam pressure, or water temperature.
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
proving controls when heated fuel oil is used.
Fuel Oil or Gas or Combination
Ignition Automatic
Firing Full Modulation Through Operating Ranges
Burner (Oil) (Low Pressure)
Air Atomizing
Burner (Gas) Non-Premix
Orificed Type
Air Damper Rotary Type
(Electrically Modulated)
Steam Trim ASME Code
Water Trim ASME Code
NOTE: A Series 100 boiler is usually equipped with a light oil pilot although a gas pilot is frequently used.
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