Vulcan-Hart MHB24G, VHX24G5 manual AIR Pressure Switch Adjustment

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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

AIR PRESSURE SWITCH

ADJUSTMENT

The air pressure switch senses the pressure level produced by the blower for combustion. When the pressure is sufficient, the switch closes and supplies power to the ignition control module. The gas ignition sequence starts to light the gas pilot and then main burner. If the gas pilot is not lighting (valve not energized), the ignition control module may not be receiving power, assuming the minimum water level is satisfied. Check the air pressure switch operation then adjust if necessary as outlined in the procedure below.

1.Turn the power switch OFF.

2.Remove the left side panel from the cabinet base.

A.Inspect the air intake to the blower for debris build up and clogging.

1)If debris is found, clean it away from the air intake.

B.Turn the power switch ON and verify main burner ignition.

1)If burner ignites then no adjustment to the pressure switch setting is necessary.

2)If burner does not ignite, proceed to step 3.

3.Open the cabinet base door and turn the ON/OFF knob for the main gas valve to OFF.

4.Adjust the air pressure switch setting as follows:

A.Turn the adjustment screw fully clockwise to the highest setting.

B.Slowly turn the adjustment screw counterclockwise until the pilot gas valve energizes then add ½ turn to the adjustment.

NOTE: The screw head should not extend out past the screw housing.

1)If Pilot gas valve energizes, proceed to step 5.

2)If Pilot gas valve does not energize, check the following:

a.Remove the lead wires from the switch and verify with a meter that the switch contacts are closing with the blower ON. If necessary, continue to turn the adjustment screw several turns counterclockwise to CLOSE the switch contacts.

b.If the switch contacts are not closing, turn the power switch OFF, remove the pressure switch from the TEE and check the air orifice for debris build up and clogging. If debris is found, clean it away from the orifice.

Page 33 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 Installation Maintenance Cleaning IntroductionGeneral 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 Water Level Controls Main or Auxiliary Llco Relay BoardCooking Compartment Controls Water Level Gauge Assembly Pressure SwitchesBoiler 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 Cooking Compartment Doors RemovalGasket 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 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