Vulcan-Hart VHX24G5, MHB24G manual N9, N10, N11, N12, N13 go out, N14, N16, N17 go out

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VHX SERIES STEAMER - ELECTRICAL OPERATION

NOTE: Relay K4 remains energized through K4(1) N.O. locking circuit.

1)N8 goes out. K4(1) N.O. contacts close and K4(1) N.C. contacts open.

2)High pressure light (control panel) goes out.

C.N11 lit. K4(2) N.O. contacts close.

1)K5 is energized (24VAC).

a.N12 lit. K5(1) N.O. contacts close.

a)Combustion blower starts.

7.N13 lit. When the combustion blower generates sufficient air pressure, the air pressure switch N.O. contacts close.

A.Ignition module is powered (24VAC).

1)Ignition module starts sparking.

2)N14 lit. Pilot voltage (PV) N.O. contacts close.

a.K7 is energized.

a)K7(1) N.O. contacts close.

3)15 sec. timer circuit (board level, solid state timer) energized and timing of pilot gas valve ON time begins.

a.K6 energized.

a)N15 lit. K6(1) N.O. close.

4)Pilot gas valve energized, pilot valve opens for gas to flow.

B.Pilot flame established. Micro amp flame "sense" current rectified to ignition module through ignition cable.

1)Sparking stops.

2)N16 lit. Main voltage (MV) N.O. contacts close.

a.N17 LED lit. Proves LLCO on water level board closed.

b.Main gas valve opens, burner lights and boiler begins to heat up.

C.15 seconds after ignition module energized, relay board timer circuit times out.

1)N15 goes out. K6 de-energized.

pilot, quickly cycle the reset switch to prevent the boiler from draining. If the pilot is not established within 90 seconds from the ignitor module being energized, the ignition module locks out power to the gas valves. The module remains locked out until the power switch is turned to OFF then ON and the manual reset switch is pressed to r e-start the ignition trial cycle.

D.As boiler heats up and builds pressure, some by-pass water/steam is produced which runs into the steam drain box. This causes the cold water condenser (CWC) solenoid to cycle, cooling the drain water and condensing any steam vapors before exiting the drain. The CWC solenoid is powered through the CWC cycling thermostat.

NOTE: On initial cold startup only, the boiler pressure may overshoot and cause the mechanical pressure relief valve to open momentarily.

E.As long as the ignition control module senses a burner flame, the internal main voltage (MV) contacts (N.O.) on the ignition module remain closed, and main gas valve stays ON.

NOTE: PV N.O. contacts are also closed, but K6 contacts are open to keep pilot valve closed.

8.Boiler steam pressure reaches upper limit set point of 10 PSI (Approx. 15 minutes).

A.Cycling pressure switch open.

1)N9, N10, N11, N12, N13 go out.

a.K5 de-energized.

a)K5(1) N.O. contacts open.

b.Combustion blower is de- energized.

a)Air pressure switch opens.

B.Ignition module is de-energized

1)PV and MV contacts open.

a.N14, N16, N17 go out.

b.Main gas valve closes, burner goes out.

c.K7 de-energized.

a)K7(1) open

a.Pilot valve closes, gas flow stops to pilot.

NOTE: If pilot ignition is not established within the allotted 15 seconds, the ignition module continues to spark. To attempt to relight the

9.Boiler steam pressure drops below lower limit set point of 8 PSI and the cycling pressure switch close.

A.Boiler steam pressure is maintained by the cycling of the pressure switch between the

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F24700 (October 2001)

 

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Contents VHX24G Shown VHX Boiler Base Series High Efficiency GAS SteamersTable of Contents VHX Series Steamers General InstallationMaintenance Cleaning Introduction 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 Cooking Compartment Controls Water Level Controls Main or Auxiliary LlcoRelay Board Boiler Assembly Water Level Gauge AssemblyPressure Switches 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 Gasket Cooking Compartment DoorsRemoval 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 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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