Chinese (Simplified)EnglishFrenchGermanHindiItalianJapaneseKoreanPortugueseRussianSpanish

Preferred Instruments

Preferred Instruments manufactures microprocessor based controllers, instruments, and electric actuators for combustion and process applications. Preferred Instruments also manufactures oil tank gauging and leak detection equipment. A major component of the Instrument group sales is from control systems integration and personal computer based Supervisory Control and Data Acquisition systems. Preferred Utilities' industrial factory is located in Danbury, CT

Chief Dispatcher, Model JC-CDBF & JC-CDDF

The Chief Dispatcher Model JC-CDBF & JC-CDDF Lead/Lag Sequencer are great lower-cost alternative to the modulating version.

Application

Lead/lag controllers reduce fuel costs by monitoring steam header pressure or water temperature and firing the correct number of boilers to maintain setpoint. Automating this function also reduces labor requirements in the boiler room. The JC-CDBF is an inexpensive lead/lag controller designed for on/off (non-modulating) boilers. The Preferred Chief Dispatcher is available for modulating boilers. The JC-CDBF can maintain steam header pressure or water temperature by cycling up to four boilers on and off. Lead boiler rotation can be manual, or automatically rotating each time the boilers are cycled to even boiler wear.

Overview

The Chief Dispatcher Model JC-CDBF Lead/Lag Sequencer is a great lower-cost alternative to the modulating version. The JC-CDBF is suitable for new and existing steam or hot water installations, irrespective of fuel type, firing rate controller, or boiler safety controls.  This sequencer does not interfere with the operation of any boiler safety or firing rate controller.

Features

  • Suitable For 2, 3, or 4 Boiler Applications
  • Steam Or Hot Water Switch Inputs
  • Rugged Controller Housing
  • Manual Lead Boiler Selection

Panel Details

Power Supply: Voltage Input: 120 VAC, 60 Hz, (240 VAC, 60 Hz optional)

Case Size: 8″ H x 8″ W x 4.87″ D

Enclosure Type: Flush Or Surface mounted

Inputs

Hot Water Header: Dry Contact, 8 FLA, ½ HP, 120 VAC (Each Boiler)

Pressure Header: Dry Contact, 8 FLA, ½ HP, 120 VAC (Each Boiler)

Outputs

Boiler Start: Dry Contact, 8 FLA, ½ HP, 120VAC (Each Boiler)

Specification

Supply a fully integrated lead/lag sequencer to coordinate the operation of two (select up to four) steam or hot water boilers.  The decision to add or delete boilers from operation will be based on boiler loading conditions.  The controller shall be housed in its own dust-tight, die-cast aluminum housing, complete with gasketed hinged door for flush or surface mounting.  A rotary lead boiler selector switch shall be externally accessible and on the controller’s front door.  Additionally, a pilot light shall be provided for each boiler.  The pilot light shall be mounted and wired so as to illuminate when the controller is calling for additional system capacity.  All connections to the lead/lag sequencer shall be electrical (i.e. no capillary tubes or pressure connections are to be connected at the control). To avoid the possibility of electrical feedbacks or cross phasing, the program control will completely isolate the individual burner control circuits.

Load demand shall be detected by (pressure or temperature) switches mounted in a common system header.  Each boiler requires its own pressure or temperature sensor provided in other sections of this specification.  All firing rate (high-low or modulating) and flame safeguard controls are assumed to be existing and in proper working order as required by other specification sections.

Boiler operation shall be as follows: The selected lead boiler will fire on demand.  If the lead boiler is unable to satisfy the load, the lag boiler(s) will be automatically brought on and off in numerical sequence as required by load conditions.  Should any burner fail, or be manually turned off, the next boiler will automatically be programmed to turn on if required.  The control system shall be a Preferred Instruments, Danbury, CT, Model JC-CDBF–x (‘x’ = boiler quantity from 2 to 4).