Vulcan-Hart MHB24G, VHX24G5 manual Main Burner Ignition Checks, Pressure Switch Adjustment

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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

MAIN BURNER IGNITION

CHECKS

The complete gas burner assembly is located inside the heat exchanger casting in the boiler. The perforated burner head functions as both pilot and main gas burner. The inner portion of the perforated burner head serves as the pilot to light the main burner during the trial for ignition. Once the main burner lights, the flame encompasses the entire perforated burner head and the pilot flame extinguishes.

If burner ignition problems are encountered, perform the following checks to ensure components are adjusted properly.

1.Turn power switch ON and allow the boiler to fill.

2.Verify "low water" and "high pressure" safety circuits are satisfied.

A.Water Level in boiler.

1)Approximately one visible inch of water in the sight glass.

2)Auxiliary LLCO is satisfied.

a.N2 on relay board ON (low water safety circuit satisfied).

b.LED on auxiliary water level board ON.

B.High Limit Pressure Switch

1)Zero reading on boiler pressure gauge.

NOTE: Burner cycles ON at less than or equal to 8 PSI and OFF at 10 PSI.

NOTE: High Limit Pressure Switch automatically resets at approximately 12 PSI.

C.Press the reset switch to reset the safety circuits.

NOTE: Hi Pressure and low water lights on front control panel should be OFF.

1)N3 on relay board ON (high pressure safety circuit satisfied).

3.Verify blower is running and its operation is quiet.

NOTE: A "noisy" blower rotation may indicate bearing wear and reduce air pressure output.

A.N12 on relay board ON (120VAC supplied to the blower).

4.Verify air pressure switch is CLOSED.

A.N13 on relay board ON (air pressure switch CLOSED and condition satisfied).

B.Pilot gas valve energized and ignition sequence starts.

NOTE: If N13 is not ON or Pilot gas valve is not energized, then check the air pressure switch setting as outlined under "AIR

PRESSURE SWITCH ADJUSTMENT".

5.Verify 24VAC to ignition module and pilot valve.

A.N1 on relay board ON (24VAC is being supplied for the system).

B.N13 on relay board ON (24VAC is being supplied to the ignition module).

C.N14 & N15 on relay board ON (24VAC is being supplied to the pilot ignition timing circuit and the pilot valve.

6.Verify spark and pilot ignition.

A.If pilot lights, proceed to step 7.

B.If sparking occurs but pilot does not light, then check the pilot pressure setting as outlined under "GAS PILOT PRESSURE ADJUSTMENT".

C.If spark is not occurring:

1)Restart power ON sequence by "rapidly" turning the power switch OFF then back ON. A rapid switching is needed to keep the boiler from starting automatic blowdown.

2)Remove ignition cable boot from the ignitor rod terminal and check ignitor position in the burner head assembly.

3)Measure distance the ignitor terminal extends past the ignitor nut. Distance should measure approximately 3/4" to 7/8". See diagram 5898 "COMPLETE BURNER ASSEMBLY" at the end of this procedure.

NOTE: Touch ignitor terminal only and not the ceramic insulator.

a.If distance is ok, proceed to step 5) below and perform step "a" and "b" then continue with step "6)".

b.If distance is other than stated, loosen ignitor nut, set the ignitor position and then re-tighten the ignitor nut.

c.Re-connect ignition cable.

4)Press reset switch to start the ignition process.

F24700 (October 2001)

 

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Contents VHX Boiler Base Series High Efficiency GAS Steamers VHX24G ShownTable of Contents VHX Series Steamers Installation Maintenance Cleaning IntroductionGeneral 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 Water Level Controls Main or Auxiliary Llco Relay BoardCooking Compartment Controls Water Level Gauge Assembly Pressure SwitchesBoiler Assembly 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 Cooking Compartment Doors RemovalGasket 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 Troubleshooting VHX Series Steamer TroubleshootingBoiler Base Controls Symptom Possible Causes Adjustments Boiler blowdown solenoid valve clogged and not fully closing Boiler Base Procedures and Adjustments VHX Series Steamer Condensed Spare Parts List VHX Series Steamer Condensed Spare Parts ListNEW Style Controls only VHX24G, VHX24G5, MHB24G
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