CleaverBrooks CBLE, Operation And Maintenance Manual

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Sequence of Operation
4-2 750-91 (revised 2009)
Model CB-LE Packaged Boiler Manual
4.2 — 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 diagram to determine the actual controls provided. The circuits and controls nor-
mally used in the circuits are identified in the following table and are referred to in Section 4.3.
Circuit Components
Limit Circuit
•
Burner switch (BS)
•
Operating limit control (OLC) - pressure or temperature
•
High limit control (HLC) - pressure or temperature
•
Low-water cutoff (LWCO)
•
Gas-oil selector switch (GOS) - combination burner only
•
Oil drawer switch (ODS) - oil burner
•
Low oil temperature switch (LOTS) - nos. 5 and 6 oil only
•
Low gas pressure switch (LGPS)
•
High gas pressure switch (HGPS)
•
LE proximity switch interlock
•
Fuel valve interlock circuit
•
Main gas valve auxiliary switch (MGVAS)
•
Oil valve auxiliary switch (OVAS)
Blower Motor Starter Circuit
•
Blower motor starter (BMS)
•
Air compressor motor starter (ACMS) - if provided
•
Air purge valve (APV) - nos. 5 and 6 oil only
Running Interlock Circuit
•
Blower motor starter interlock (BMSI)
•
Combustion air proving switch (CAPS)
•
Atomizing air proving switch (AAPS) - if provided
Low Fire Proving Circuit
•
Low fire switch (LFS)
Pilot Ignition Circuit
•
Gas pilot valve (GPV)
•
Ignition transformer (IT)
•
Gas pilot vent valve (GPVV) - if provided
Flame Detector Circuit
•
Flame detector (FD)
•
Main fuel valve circuit
•
Main gas valve (MGV)
•
Main gas vent valve (MGVV) - if provided
•
Oil valve (OV)
•
Main fuel valve light (FVL)