Crown Boiler CWI103, CWI172 Sequence of Operation, Intermittent Ignition, Less Tankless Heater

Page 25

Sequence of Operation, Intermittent Ignition, Less Tankless Heater

1)When the boiler is energized, 24 volts is immediately applied to terminals “1” (blue) and “4” (yellow) on the vent damper. Assuming that there is no call for heat, and that the damper switch is in the “automatic” position, the damper will close.

2)A call for heat from the thermostat energizes relay coil 1R (the relay on the L8148E), causing contacts 1R1 and 1R2 to make. Contact 1R1 starts the circulator. Contact 1R2 sends power to the high limit.

3)Assuming that the high limit is made, current will flow to pin terminal #2 (orange) at the vent damper and the damper will open.

4)Once the vent damper is fully open, an end switch inside the damper will make, energizing pin #3 (red) at the damper. This pin is connected through the damper harness to terminal “B1” on the L8148E. At this point in the operating sequence, 24 volts is present across “B1” and “B2”.

5)Under normal conditions, the flame roll-out switch and blocked vent switch are made. Voltage will therefore immediately appear across the “24V” and “24V (GND)” terminals on the ignition module.

6)Upon application of voltage across the “24V” and “24V (GND)” terminals, the ignition module will start an ignition spark at the pilot and apply 24 volts across the pilot valve (terminals “PV” and “MV/PV”).

7)Once the pilot is established, the pilot flame will act as a diode, converting the AC current at the electrode to a half wave DC current at the pilot’s ground strap. This DC current flows through the boiler to the “GND (BURNER)” connection on the ignition module. For the ignition module to recognize that a pilot flame is present, the DC current flowing into this terminal must be in excess of approximately 1.0 uA.

8)Once the ignition module detects the presence of a pilot flame, voltage is applied across the main valve (terminals “MV” and “MV/PV”), opening the valve and establishing main flame.

9)The way in which the ignition module handles failure to establish pilot or the loss of an already established pilot depends upon the exact ignition module supplied with the boiler. For more information on module operation, consult the ignition module instructions supplied with the boiler or the local Crown representative.

Sequence of Operation, Intermittent Ignition, With Tankless Heater

1)When the boiler is energized, 24 volts is immediately applied to terminals “1” (blue) and “4” (yellow) on the vent damper. Assuming that there is no call for heat, and that the damper switch is in the “automatic” position, the damper will close.

2)If the boiler water temperature is less than the low limit setting minus the differential setting, terminals “R” and “B” in the L8124E are made through the low limit switch. The low limit switching action is SPDT with “R” being common. “R” and “W” are therefore open whenever “R” and “B” are made. This means that while “R” and “B” are made relay coil R1 is deenergized, regardless of whether or not there is a call for heat. The circulator will therefore not operate if the boiler water temperature is too low to generate domestic hot water.

3)Assuming that the high limit is made, current will flow to terminal “B1” on the L8124E and then to terminal “2” (orange) at the vent damper and the damper will open.

4)Once the vent damper is fully open, an end switch inside the damper will make, energizing pin #3 (red) at the damper. The red wire from this pin runs to the flame rollout switch.

5)Under normal conditions, the flame roll-out switch and blocked vent switch are made. Voltage will therefore immediately appear across the “24V” and “24V (GND)” terminals on the ignition module.

6)Upon application of voltage across the “24V” and “24V (GND)” terminals, the ignition module will start an ignition spark at the pilot and apply 24 volts across the pilot valve (terminals “PV” and “MV/PV”).

7)Once the pilot is established, the pilot flame will act as a diode, converting the AC current at the electrode to a half wave DC current at the pilot’s ground strap. This DC current flows through the boiler to the “GND (BURNER)” connection on the ignition module. For the ignition module to recognize that a pilot flame is present, the DC current flowing into this terminal must be in excess of approximately 1.0 uA.

8)Once the ignition module detects the presence of a pilot flame, voltage is applied across the main valve (terminals “MV” and “MV/PV”), opening the valve and establishing main flame.

9)The way in which the ignition module handles failure to establish pilot or the loss of an already established pilot depends upon the exact ignition module supplied with the boiler. For more information on module operation, consult the ignition module instructions supplied with the boiler or the local Crown representative.

10)The boiler will fire until the boiler water temperature is approximately equal to the low limit setting. Once the water temperature reaches this point, “R” and “B” open and “R” and “W” make. At this point, a call for heat from the thermostat will energize 1R, making contacts 1R1 and 1R2. Contacts 1R1 energize the circulator. Contacts 1R2 switch current from the “hot” side of the transformer secondary to the high limit switch. If the high limit is made, current flows to terminal “B1” and the ignition sequence is then the same as it is for a call for burner operation from the low limit (see (3) above).

25

24

Image 25
Contents CWI Series Gas-Fired Natural Draft Water Boilers INSTALLATION INSTRUCTIONSModels These instructions must be affixed on or adjacent to the boilerI Product Description Table of ContentsFIGURE 1 CWI BOILERS - GENERALCONFIGURATION II SpecificationsTABLE 1 CWI SPECIFICATIONS IV Locating the Boiler III Before InstallingV Air for Combustion and Ventilation ForBuildingsofUnusuallyTightConstruction For Buildings of Other than Unusually Tight ConstructionExample FIGURE 4 ALL AIR FROM OUTDOORS, VENTILATED CRAWL SPACE AND ATTIC FIGURE3BOILERINSTALLEDINCONFINEDSPACE, ALL AIR FROM INSIDEFIGURE 5 ALL AIR FROM OUTDOORS VIA VENTILATED ATTIC FIGURE 6 ALL AIR FROM OUTDOORS, USING OPENINGS INTO BOILER ROOM VI Venting Removing an Existing Boiler from a Common Chimney FIGURE 9 VENT DAMPER INSTALLATION DETAILS FIGURE8 CWI BOILERTYPICALVENTSYSTEM INSTALLATION AND COMPONENTSVII Gas Piping StandardPiping VIII System PipingDANGER Piping for Special Situations 1413BOILERSIDEPIPING FIGURE 11 STANDARD BOILER PIPING FIGURE 12 INDIRECT WATER HEATERFIGURE13 BOILERBYPASSPIPING FIGURE15 BOILERPIPINGWITHCHILLER FIGURE14 ISOLATIONOFBOILERFROMSYSTEMWITHAHEATEXCHANGERIX TANKLESS HEATER PIPING Feel water before showering or bathing A mixing valve does not eliminate the risk of scaldingFIGURE 17TANKLESSHEATERPIPING SingleZoneWiring IX WiringFIGURE 20 WIRING DIAGRAM, STANDING PILOT WITH TANKLESS HEATER Wiring Variations FACTORY BOILER WIRING NOT SHOWN - SEE FIGURES 18 FIGURE 22 CIRCULATOR ZONEWIRING USING HONEYWELLR845AsFIGURE23ZONEWIRINGUSINGHONEYWELLV8043FZONEVALVES FACTORYWIRING NOT SHOWN - SEE FIGURES 18Sequence of Operation, Standing Pilot, Less Tankless Heater CWI Control System - Sequence of OperationSequence of Operation, Standing Pilot, With Tankless Heater Sequence of Operation, Intermittent Ignition, With Tankless Heater Sequence of Operation, Intermittent Ignition, Less Tankless HeaterSafety Control Operation - Standing Pilot and Intermittent Ignition XI Start-up and CheckoutFIGURE 24 STANDING PILOT BURNER FLAME 2726Page Page LIGHTING INSTRUCTIONS FOR YOUR SAFETY READ BEFORE OPERATINGTO TURN OFF GAS TO APPLIANCE LIGHTING INSTRUCTIONS FOR BOILERS EQUIPPED WITH HONEYWELLLIGHTING INSTRUCTIONS FOR BOILERS EQUIPPED WITH ROBERTSHAW FOR YOUR SAFETY READ BEFORE LIGHTING7000ERHC SERIES GAS VALVES STANDING PILOT OPERATING INSTRUCTIONS FOR YOUR SAFETY READ BEFORE LIGHTINGTO TURN OFF GAS TO APPLIANCE VR8204 AND VR8304 SERIES GAS VALVES INTERMITTENT PILOT7000DERHC SERIES GAS VALVES INTERMITTENT PILOT FIGURE 28b GASVALVEDETAIL-ROBERTSHAW 7000DERHC INTERMITTENT IGNITION FIGURE 27a GASVALVEDETAIL-HONEYWELLVR8200ORVR8300STANDINGPILOTXI Service and Maintenance Heat Exchanger Cleaning Procedure XIII Troubleshooting C1&C2? STARTNational Fuel Gas Code 5&6 onL2 ? STARTT&TV? C1&C2?C2 and Caution Read page 36 before attempting to use this chart Standing Pilot Ignition System Troubleshooting ChartIntermittent Ignition System Troubleshooting Chart XIV PARTS Page 1/4 Pilot Tubing Used with Robertshaw Valves These Valves Piped in Series to Provide Redundent Shut-off40mm BURNERS ONLY Page KEY # Page A. Before Installing Appendix A Knockdown Boiler Assembly InstructionsB. BaseAssembly Preparation C. Heat Exchanger and Flue Collector InstallationFIGUREA1 BASE, HEAT EXCHANGER, FLUE COLLECTORASSEMBLY E. Control and Trim Installation D. Gas Valve InstallationFIGURE A2 JACKET INSTALLATION G. Complete Installation F. Electrical Wiring ConnectionsFIGURE A3 TAPPING LOCATIONS SEE TEXT FOR TAPPING USES 3633 I. Street P.O. BoxPhiladelphia