Vulcan-Hart MHB24G, VHX24G5 manual VHX Series Steamer Electrical Operation

Page 49

VHX SERIES STEAMER - ELECTRICAL OPERATION

3.Water level reaches LLCO (low water level cut- off) probe for the water level control and to the auxiliary LLCO probe for the auxiliary low level cut-off control.

A.LLCO relay energizes, LLCO contacts (N.O.) CLOSE and LED lights.

NOTE: No power is transferred until ignition sequence starts.

B.Aux. LLCO relay energizes, LLCO contacts (N.O.) CLOSE and LED lights.

NOTE: The LLCO and aux. LLCO relays will remain energized and LLCO LED’S will remain lit until the water level drops below the LLCO probes or the power switch is turned OFF.

4.Water reaches LL (low level) probe.

5.Water reaches HL (high level) probe.

A.Fill solenoid is de-energized.

6.Press the manual reset switch.

A.Relay coil (R1) energized.

1)High pressure light turns OFF.

B.Relay coil (R3) energized.

1)Low water light turns OFF.

2)Transformer (T1) energized.

7.24VAC is connected through the cycling pressure switch contacts to the following components:

A.Normally open (N.O.) side of the air pressure switch.

NOTE: No power is transferred until air pressure switch CLOSES.

B.Relay coil (R2) is energized and R2 contacts (N.O.) CLOSE.

1)120VAC is supplied to the combustion air blower and blower starts.

C.Once the combustion blower develops sufficient pressure, the air pressure switch

CLOSES.

1)24VAC is then applied to the Ignition control module and the ignition cycle starts.

a.Pilot voltage (PV) N.O. contacts

CLOSE.

b.Pilot gas valve energized, pilot valve opens for gas to flow and Ignitor begins sparking to light pilot.

2)Pilot ignition is established (pilot lit) and a micro amp flame "sense" current is sent back to the ignition module through the ignition cable.

3)Main voltage (MV) N.O. contacts

CLOSE.

a.Main gas valve OPENS, burner lights and boiler begins to heat up.

NOTE: 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 by the CWC thermostat.

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

b.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.

c.If sparking is allowed to continue for a total of 90 seconds, then the ignition module locks out power to the gas valve (pilot valve and main valve remain closed). The module remains locked out until the power switch is turned to OFF then ON and the manual reset switch is pressed to re-start the ignition trial cycle.

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

A.Cycling pressure switch opens and power is removed from the following components:

1)Combustion air pressure switch normally open (N.O.) terminal.

2)Relay coil (R2) returning R2 contacts to there N.O. shelf state.

a.Combustion air blower de- energized.

B.Ignition control module is de-energized, PV and MV contacts OPEN.

1)Main gas solenoid valve de- energizes, gas flow shuts OFF and burner goes out.

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

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

Page 49 of 68

 

F24700 (October 2001)

 

Page 48 Page 50
Image 49
Page 48 Page 50
Contents VHX24G Shown VHX Boiler Base Series High Efficiency GAS SteamersTable of Contents VHX Series Steamers Maintenance Cleaning Introduction InstallationGeneral Boiler Control Styles System Water Conditioning SpecificationsWater Supply ElectricalGas Supply ToolsStandard SpecialCabinet Base Boiler Steamer OperationCooking Compartment Controls VHX Series Steamers OperationBoiler Blowdown Steamer Shut OFF VHX Series Steamers Component Function Component FunctionBlowdown/Drain Ignition Control ModuleWater Level Steam Header AssemblyWater Inlet Valve manual Pressure Relief ValveSteam Solenoid Valve Compartment Pressure SwitchManifold Pressure Gauge Steam Supply ManifoldVHX Series Steamers Removal and Replacement of Parts Removal and Replacement of PartsComponent Locations Cabinet Base Boiler ControlsCabinet 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 AssemblyClean-Out Service Procedures and AdjustmentsBoiler InspectionDescaler 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 Door Sealing Adjustment Intake Shut-Off Valve Adjustment Steam FlowCooking Compartment Cooking Compartment DoorsVHX Series Steamer Electrical Operation Door Latch AdjustmentLow Level Cut-Off & Differential Control Electrical OperationAuxiliary Low Level Cut-Off LED Legend Board Layout and LED LegendReset Engaged State C Boiler Operational Status LED IndicatorInitial Conditions State a Aux Water Level Satisfied State BK32 Close Air Pressure Switch Satisfied State DK51 Close Burner ON, Boiler Heating to generate steam State ENEW Style Controls Boiler Sequence of OperationInitial Fill and Preheat HL-LEDN14, 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
Top Page Image Contents