Symptom Possible Causes | Vulcan-Hart VHX24G5, MHB24G specification

VHX SERIES STEAMER - TROUBLESHOOTING

SYMPTOM			POSSIBLE CAUSES

Blower operating, no pilot gas flow.	1.	Main gas supply turned OFF.
	2.	Ignition module lockout. Turn power switch OFF for several
		seconds then ON to reset the module.
	3.	Air pressure switch:
		A. Not mounted in true vertical position.
		B.	Incorrect pressure setting.
		C.	Malfunctioning switch.
	4.	Malfunctioning Ignition module.
	5.	Malfunctioning pilot gas valve.
	6.	Blocked or dirty pilot gas orifice.

Pilot flame not proving or lighting main	1.	Gas not ON.
burner.	2.	Incorrect manifold pressure for pilot gas.
	3.	Poor connection between igniter and ignition cable.
	4.	Fouled spark igniter.
	5.	Incorrect gap in spark igniter.
	6.	Faulty igniter or cracked insulation.
	7.	Improper ground.
	8.	Low water level in boiler or boiler not filling.
	9.	Flame sensing current too low.
	10.	Cracked or incorrect burner head attachment.
	11.	Incorrect igniter positioning.
	12.	Incorrect pilot orifice.

Main burner not lighting correctly or	1.	Blocked or dirty air orifice on blower.
excessive ignition noise.	2.	Insufficient gas supply pressure.
	3.	Incorrect gas pilot pressure.
	4.	Incorrect gas manifold pressure.
	5.	Pilot flame not sensing correctly.
	6.	Burner tube insulation broken or deteriorated.
	7.	Blocked or restricted flue.
	8.	Incorrect pilot or main gas burner orifice size.

Excess combustion noise or combustion	1.	Blocked or dirty air orifice on blower.
induced harmonics.	2.	Incorrect gas manifold pressure.
	3.	Insufficient gas supply pressure.
	4.	Steam vapors introduced into blower inlet.
	5.	Loose flue connections.

Boiler not maintaining set pressure	1.	Leaking boiler blowdown valve.
and/or excessive burner on time.	2.	Manual blowdown valve on water level probe housing open.
	3.	Malfunctioning 13 psi overshoot relief valve.
	4.	Low incoming gas supply pressure.
	5.	Excessive load on steam outlet.

F24700 (October 2001)		Page 62 of 68

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Vulcan-Hart VHX24G5, MHB24G manual Symptom Possible Causes

Contents

VHX Boiler Base Series High Efficiency GAS Steamers VHX24G Shown Table of Contents VHX Series Steamers General InstallationMaintenance Cleaning Introduction Boiler Control Styles Water Supply Water Conditioning SpecificationsSystem Electrical Standard ToolsGas Supply Special Cooking Compartment Controls Steamer OperationCabinet Base Boiler VHX Series Steamers Operation Boiler Blowdown Steamer Shut OFF Blowdown/Drain Component FunctionVHX Series Steamers Component Function Ignition Control Module Water Inlet Valve manual Steam Header AssemblyWater Level Pressure Relief Valve Manifold Pressure Gauge Compartment Pressure SwitchSteam Solenoid Valve Steam Supply Manifold Component Locations Removal and Replacement of PartsVHX Series Steamers Removal and Replacement of Parts Cabinet Base Boiler Controls Cabinet 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 Valves Burner Head Assembly Complete Burner Assembly Heat Exchanger VHX Series Steamers Removal and Replacement of Parts Gasket Cooking Compartment DoorsRemoval Latch Assembly Handle Boiler Service Procedures and AdjustmentsClean-Out Inspection Water Level Probe Housing Blowdown Descaler Cathodic Protector Water Level Controls Test Auxiliary Low level Cut-Off Control High Limit Cycling Fill and Cold Water Solenoid Valves Small increments Inline Water Strainer Cleaning Boiler BLOWDOWN/DRAIN Solenoid Valve Pressure Switch Adjustment Main Burner Ignition Checks GAS 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 Terminals Spark Verification Test Cooking Compartment Intake Shut-Off Valve Adjustment Steam FlowDoor Sealing Adjustment Cooking Compartment Doors Door Latch Adjustment VHX Series Steamer Electrical Operation Electrical Operation Low Level Cut-Off & Differential Control Auxiliary Low Level Cut-Off Board Layout and LED Legend LED Legend Initial Conditions State a Boiler Operational Status LED IndicatorReset Engaged State C Aux Water Level Satisfied State B K51 Close Air Pressure Switch Satisfied State DK32 Close Burner ON, Boiler Heating to generate steam State E Initial Fill and Preheat Sequence of OperationNEW Style Controls Boiler HL-LED N9, N10, N11, N12, N13 go out N14, N16, N17 go out Water Refill After Initial Fill Boiler Blowdown/drain VHX Series Steamer Electrical Operation Cooking Compartment Controls This page Intentionally Left Blank Schematics Models Built After 5/25/00 New Style Boiler Controls VHX 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