Vulcan-Hart MHB24G, VHX24G5 manual Auxiliary Low Level Cut-Off

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VHX SERIES STEAMER - ELECTRICAL OPERATION

Auxiliary Low Level Cut-Off

This control serves as a safety backup to the main water level control (WLC) board to meet CSD-1 code requirements. The operation of the auxiliary control is identical to the low level cut-off (LLCO) function of the main WLC board but performs a single function: 1) Provide auxiliary low level cut-off protection to shut off the heat source in case the water level drops below the low level cut-off (LLCO) probe. A single LLCO probe, identical to the LLCO probe on the main WLC board, is connected to the auxiliary control.

The auxiliary water level control (WLC) has input voltage (120VAC) across terminals 11 and 12 which powers the primary side of the transformer. On one side of the transformer secondary, power is provided to the control by a series path through chassis ground (terminal 10). The other side of the transformer secondary (12VAC) is attached to the control that directs power to the other side of the internal relay (LLCO). As water enters the boiler, it becomes part of the auxiliary water level control’s circuit. When the water level in the boiler reaches the LLCO probe, the circuit is completed.

When the main power switch is turned ON, power is supplied to the auxiliary WLC board but no switching occurs. Also, the low water level indicator light (amber) on the boiler base control panel comes on.

When the water level reaches the low level cut-off (LLCO) probe, the LLCO relay is energized (LLCO-2 close) and the LLCO LED lights up. The LLCO relay will remain energized and its LED will stay lit until the water level in the boiler drops below the LLCO probe.

When the boiler stops filling, press the manual reset switch on the boiler base control panel. This turns off the low water light, energizes the combustion blower and allows the ignition cycle to begin.

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Contents VHX Boiler Base Series High Efficiency GAS Steamers VHX24G ShownTable of Contents VHX Series Steamers Installation Maintenance Cleaning IntroductionGeneral Boiler Control Styles Water Supply Water Conditioning SpecificationsSystem ElectricalStandard ToolsGas Supply SpecialCooking Compartment Controls Steamer OperationCabinet Base Boiler VHX Series Steamers OperationBoiler Blowdown Steamer Shut OFF Blowdown/Drain Component FunctionVHX Series Steamers Component Function Ignition Control ModuleWater Inlet Valve manual Steam Header AssemblyWater Level Pressure Relief ValveManifold Pressure Gauge Compartment Pressure SwitchSteam Solenoid Valve Steam Supply ManifoldComponent Locations Removal and Replacement of PartsVHX Series Steamers Removal and Replacement of Parts Cabinet Base Boiler ControlsCabinet Base Boiler Controls Water Level Controls Main or Auxiliary Llco Relay BoardCooking Compartment Controls Water Level Gauge Assembly Pressure SwitchesBoiler Assembly Pilot GAS Valve Main GAS Valve Boiler Fill and Cold Water Condenser Solenoid ValvesBurner Head Assembly Complete Burner AssemblyHeat Exchanger VHX Series Steamers Removal and Replacement of Parts Cooking Compartment Doors RemovalGasket Latch Assembly HandleBoiler Service Procedures and AdjustmentsClean-Out InspectionWater Level Probe Housing Blowdown Descaler Cathodic ProtectorWater Level Controls TestAuxiliary Low level Cut-Off Control High Limit CyclingFill and Cold Water Solenoid Valves Small incrementsInline Water Strainer Cleaning Boiler BLOWDOWN/DRAIN Solenoid ValvePressure Switch Adjustment Main Burner Ignition ChecksGAS Manifold Pressure Adjustment VHX Series Steamer Service Procedures and Adjustments AIR Pressure Switch Adjustment GAS Pilot Pressure Adjustment Pressure Readings Inches W.C GAS Manifold Pressure Adjustment Ignition Control Module Checks TerminalsSpark Verification Test Cooking Compartment Intake Shut-Off Valve Adjustment Steam FlowDoor Sealing Adjustment Cooking Compartment DoorsDoor Latch Adjustment VHX Series Steamer Electrical OperationElectrical Operation Low Level Cut-Off & Differential ControlAuxiliary Low Level Cut-Off Board Layout and LED Legend LED LegendInitial Conditions State a Boiler Operational Status LED IndicatorReset Engaged State C Aux Water Level Satisfied State BK51 Close Air Pressure Switch Satisfied State DK32 Close Burner ON, Boiler Heating to generate steam State EInitial Fill and Preheat Sequence of OperationNEW Style Controls Boiler HL-LEDN9, N10, N11, N12, N13 go out N14, N16, N17 go outWater Refill After Initial Fill Boiler Blowdown/drainVHX Series Steamer Electrical Operation Cooking Compartment Controls This page Intentionally Left Blank Schematics Models Built After 5/25/00 New Style Boiler ControlsVHX Series Steamer Electrical Operation Models Built Before 5/25/00 Old Style Boiler Controls Cooking Compartment Controls Wiring Diagrams VHX Series Steamer Electrical Operation Models Built Before 5/25/00 Old Style Boiler Controls VHX Series Steamer Electrical Operation Cooking Compartment Controls Troubleshooting VHX Series Steamer TroubleshootingBoiler Base Controls Symptom Possible Causes Adjustments Boiler blowdown solenoid valve clogged and not fully closing Boiler Base Procedures and Adjustments VHX Series Steamer Condensed Spare Parts List VHX Series Steamer Condensed Spare Parts ListNEW Style Controls only VHX24G, VHX24G5, MHB24G