Vulcan-Hart VHX24G5, MHB24G manual Auxiliary Low level Cut-Off Control

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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

C.Verify LED’s on the water level control board, HL LED should be off, and LLCO LED should be illuminated.

3.Open the ball valve in the probe housing assembly (boiler left side) about half way, to gradually remove boiler water and activate a fill cycle. Do not press the reset switch to start the ignition cycle. The next step requires a visual sight glass measurement that cannot be obtained, if there is boiling action in the vessel.

A.Verify water level in the boiler sight glass drops 1/4" to 3/8" before a fill cycle is initiated. Repeat at least twice to verify correct fill.

1)If proper fill wasn’t obtained:

a.Verify probes 50, 51, and 52 have the correct colored wire to them and to the water level control board.

b.Remove the 3 probe assembly, clean lime scale build-up from the probes and compare probe lengths to drawing.

c.Remove 3/8” flex line from the probe housing assembly to the boiler and remove any obstructions. The 1/4" compression fitting elbow and 1/4" tee into the boiler shell for the balance tube are sloped 1/8" so condensation drains into boiler. When replacing, the assembly must have this slope to prevent a blockage from condensate build-up.

4.Test the water level control board LLCO circuit.

A.With the boiler full with water, turn off the water supply and open the ball valve in the probe housing assembly.

B.Shortly after the water drops below the lowest visible level in the sight glass, the LLCO LED on the water level control board should turn off, LLCO relay should de-energize and the normally open contacts should return there shelf state.

C.Repeat at least twice to verify correct LLCO operation.

Auxiliary Low level Cut-Off Control

5.Continued testing with focus on the auxiliary LLCO circuit. With water below the lowest visible level in the sight glass (below Aux LLCO probe), and boiler in state of initial fill:

A.Verify Aux LLCO LED is off on the Aux water level control board.

B.Verify Low Water light is illuminated (front control panel).

C.Verify 24 volt AC is on Aux LLCO COM, and 0 volt is on Aux LLCO N.O. contacts.

1)With the water level above the Aux LLCO probe and in the initial fill state:

a.Verify Aux LLCO LED is illuminated on the auxiliary low water board.

b.Verify N2 on the relay board is illuminated (new style boiler controls only).

c.Verify the "green" ready light in the reset switch is illuminated.

d.Verify 24 volt AC is on the Aux LLCO common and normally open contacts of the auxiliary water level control board.

2)With the main gas valve turned off, water supply valve turned off, and probe housing assembly ball valve opened, press the reset switch.

a.Verify low water light (front control panel).

b.Blower comes on.

c.Gas pilot cycles at approximately 15 seconds on and 5 seconds off.

3)Shortly after water level drops below the lowest visible level in the sight glass, the Aux LLCO circuit should be activated.

a.Low water light turns on.

b.Aux LLCO led turns off.

c.Combustion blower is de- energized.

d.Gas pilot stops cycling.

4)Press reset switch to verify lockout.

5)Disconnect lead wire from Aux LLCO probe. If there is any measurable resistance between the probe and the

F24700 (October 2001)

 

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Contents VHX Boiler Base Series High Efficiency GAS Steamers VHX24G ShownTable of Contents VHX Series Steamers General InstallationMaintenance Cleaning Introduction 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 Cooking Compartment Controls Water Level Controls Main or Auxiliary LlcoRelay Board Boiler Assembly Water Level Gauge AssemblyPressure Switches 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 Gasket Cooking Compartment DoorsRemoval 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 Boiler Base Controls TroubleshootingVHX Series Steamer Troubleshooting Symptom Possible Causes Adjustments Boiler blowdown solenoid valve clogged and not fully closing Boiler Base Procedures and Adjustments VHX Series Steamer NEW Style Controls only VHX24G, VHX24G5, MHB24G Condensed Spare Parts ListVHX Series Steamer Condensed Spare Parts List
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