Vulcan-Hart MHB24G, VHX24G5 manual Board Layout and LED Legend

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VHX SERIES STEAMER - ELECTRICAL OPERATION

RELAY BOARD

Board Layout and LED Legend

The relay board Provides a centralized location for wire harness connections and power transfer through board relays (K1-K7) to the other steamer controls. Also, provides a condition or component troubleshooting indicator by utilizing seventeen LED’S on the board to represent the status of the condition or component in the operating sequence. When the condition for the component being monitored is satisfied or activated, an LED will light to indicate its proper operation. If the corresponding LED does not light then the condition or component has not been satisfied or is not activated.

LED LEGEND

LED ON = Condition satisfied or component activated. 1 LED OFF = Condition not satisfied or component de-activated.

LED	DESCRIPTION	LED	DESCRIPTION

N1	Board powered (24vac).	N10	Auxiliary water level satisfied (LLCO) and reset switch
			activated.

N2	Auxiliary water level satisfied (LLCO).	N11	Boiler operating pressure condition satisfied and reset
			switch activated.

N3	High limit pressure switch closed.	N12	Combustion blower ON.

N4	Steamer is ready (ready light "green" is ON).	N13	Combustion blower air pressure switch satisfied.

N5	Auxiliary water level satisfied (LLCO) and reset switch activated.	N14	Ignition module pilot voltage (PV) to board level timing
			circuit.

N6 1	Low water condition exists (N2 LED ON) or previously existed. If	N15 2	Pilot voltage (PV) to pilot gas valve.
	water level condition is satisfied and the reset switch is activated
	then N6 LED will turn off.

N7	Boiler pressure condition satisfied and reset switch activated.	N16	Ignition module main voltage (MV) to low water level
			contacts (LLCO) on water board.

N8 1	Boiler High pressure condition exists (N3 LED ON) or previously	N17	Low water level satisfied (LLCO) and main voltage (MV)
	existed. If boiler pressure condition is satisfied and the reset switch		from ignition module is supplied to main gas valve.
	is activated then N8 led will turn off.

N9	Cycling pressure switch CLOSED “call for heat”.

NOTES: 1. At initial power on, N6 & N8 led’s will be ON until conditions are satisfied and reset switch is activated.

2. Board level timing circuit energized and powers pilot gas valve for approximately 15 seconds then de-energizes.

Page 43 of 68		F24700 (October 2001)

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Contents VHX24G Shown VHX Boiler Base Series High Efficiency GAS SteamersTable of Contents VHX Series Steamers Maintenance Cleaning Introduction InstallationGeneral Boiler Control Styles Electrical Water Conditioning SpecificationsSystem Water SupplySpecial ToolsGas Supply StandardVHX Series Steamers Operation Steamer OperationCabinet Base Boiler Cooking Compartment ControlsBoiler Blowdown Steamer Shut OFF Ignition Control Module Component FunctionVHX Series Steamers Component Function Blowdown/DrainPressure Relief Valve Steam Header AssemblyWater Level Water Inlet Valve manualSteam Supply Manifold Compartment Pressure SwitchSteam Solenoid Valve Manifold Pressure GaugeCabinet Base Boiler Controls Removal and Replacement of PartsVHX Series Steamers Removal and Replacement of Parts Component LocationsCabinet Base Boiler Controls Relay Board Water Level Controls Main or Auxiliary LlcoCooking Compartment Controls Pressure Switches Water Level Gauge AssemblyBoiler Assembly Boiler Fill and Cold Water Condenser Solenoid Valves Pilot GAS Valve Main GAS ValveComplete Burner Assembly Burner Head AssemblyHeat Exchanger VHX Series Steamers Removal and Replacement of Parts Removal Cooking Compartment DoorsGasket Handle Latch AssemblyInspection Service Procedures and AdjustmentsClean-Out BoilerDescaler Cathodic Protector Water Level Probe Housing BlowdownTest Water Level ControlsAuxiliary Low level Cut-Off Control Cycling High LimitSmall increments Fill and Cold Water Solenoid ValvesBoiler BLOWDOWN/DRAIN Solenoid Valve Inline Water Strainer CleaningMain Burner Ignition Checks Pressure Switch AdjustmentGAS 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 Terminals Ignition Control Module ChecksSpark Verification Test Cooking Compartment Doors Intake Shut-Off Valve Adjustment Steam FlowDoor Sealing Adjustment Cooking CompartmentVHX Series Steamer Electrical Operation Door Latch AdjustmentLow Level Cut-Off & Differential Control Electrical OperationAuxiliary Low Level Cut-Off LED Legend Board Layout and LED LegendAux Water Level Satisfied State B Boiler Operational Status LED IndicatorReset Engaged State C Initial Conditions State aBurner ON, Boiler Heating to generate steam State E Air Pressure Switch Satisfied State DK32 Close K51 CloseHL-LED Sequence of OperationNEW Style Controls Boiler Initial Fill and PreheatN14, N16, N17 go out N9, N10, N11, N12, N13 go outBoiler Blowdown/drain Water Refill After Initial FillVHX Series Steamer Electrical Operation Cooking Compartment Controls This page Intentionally Left Blank Models Built After 5/25/00 New Style Boiler Controls SchematicsVHX 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 VHX Series Steamer Troubleshooting TroubleshootingBoiler Base Controls Symptom Possible Causes Adjustments Boiler blowdown solenoid valve clogged and not fully closing Boiler Base Procedures and Adjustments VHX Series Steamer VHX Series Steamer Condensed Spare Parts List Condensed Spare Parts ListNEW Style Controls only VHX24G, VHX24G5, MHB24G