Crown Boiler BSI241, BSI276, BSI345, BSI379, BSI103, BSI138 BSI Control System Sequence of Operation

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BSI Control System – Sequence of Operation

(Refer to Figures 16 through 19 for ladder and connection diagrams)

Sequence of Operation, Standing Pilot

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. On boilers equipped with Hydrolevel CG400A probe type low water cut-offs, voltage is also always applied to terminals “1” (blue) and “2” (yellow) on the low water cut-off to power the water level sensing circuit. On boilers equipped with #67 float type low water cut-offs, power is always applied to terminal “2” on the #67 LWCO.

2)Assuming that water is above the cut-off level, power will appear at terminal “3” on the CG400 LWCO or terminal “1” on the #67 LWCO.

3)Assuming that steam pressure is below the pressure limit setting, power will appear on one side of relay contact 1R1 (Gray lead). Relay 1R is the R8225 mounted under the junction box.

4)A call for heat from the thermostat energizes relay coil 1R causing contacts 1R1 to make. Current then flows through contacts 1R1 to pin terminal “2” (orange) at the vent damper and the damper opens.

5)Once the vent damper is fully open, an end switch inside the damper will make, energizing pin “3” (red) at the damper.

6)Current passes from terminal “3” on the vent damper though the flame rollout and blocked vent (“spill”) switches. Under normal conditions, both of these switches are made and voltage will therefore immediately appear across the combi- nation gas control (“gas valve”) terminals “TH” and “TR”.

7)When the boiler is first placed into operation, the pilot must be lit. The pilot heats a thermocouple which generates a small amount of electricity sufficient to hold open the safety shut-off valve in the combination gas control. The circuit connecting the thermocouple and the safety shut-off valve is self contained and completely independent of all other wiring on the boiler. This safety shut-off valve is upstream of the 24 volt valves in the gas control which open in response to a call for heat. If the pilot is not lit, the safety shut-off valve will remain closed and gas will not reach the 24 volt valves.

8)Assuming that the pilot is established and proven by the thermocouple, the application of 24 volts across the combina- tion gas valve terminals energizes the redundant 24 volt solenoid valves in the combination gas control, resulting in gas flow through the control and burner operation.

Sequence of Operation, Intermittent Ignition

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. On boilers equipped with Hydrolevel CG400A probe type low water cut-offs, voltage is also always applied to terminals “1” (blue) and “2” (yellow) on the low water cut-off to power the water level sensing circuit. On boilers equipped with #67 float type low water cut-offs, power is always applied to terminal “2” on the #67 LWCO.

2)Assuming that water is above the cut-off level, power will appear at terminal “3” on the CG400 LWCO or terminal “1” on the #67 LWCO.

3)Assuming that steam pressure is below the pressure limit setting, power will appear on one side of relay contact 1R1 (Gray lead). Relay 1R is the R8225 mounted under the junction box.

4)A call for heat from the thermostat energizes relay coil 1R causing contacts 1R1 to make. Current then flows through contacts 1R1 to pin terminal “2” (orange) at the vent damper and the damper opens.

5)Once the vent damper is fully open, an end switch inside the damper will make, energizing pin “3” (red) at the damper.

6)Current passes from terminal “3” on the vent damper though the flame rollout and blocked vent (“spill”) switches. Under normal conditions, both of these switches are made and voltage will therefore immediately appear across terminals “24V” and “24V (GND)” on the ignition module.

7)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”).

8)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.

9)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.

10)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.

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Contents BSI Series Table of Contents Product DescriptionII Specifications BSI SpecificationsIII Before Installing IV Locating the BoilerAir for Combustion and Ventilation For Buildings of Other than Unusually Tight Construction ForBuildingsofUnusuallyTightConstructionBOILERINSTALLEDINCONFINEDSPACE, ALL AIR from Inside ALL AIR from OUTDOORS, Using Openings Into Boiler Room VI Venting Removing an Existing Boiler from a Common Chimney BSI Boilertypicalventsystem Installation and Components VII Gas Piping GasconnectiontoboilerViii System Piping General Piping NotesPipingInstallation Common NEAR-BOILER Piping Mistakes IX Indirect Water Heater Piping Indirectwater Heater BOILER-SIDE PipingWiring Indirect Water Heater Wiring Wiring Indirectwater Heater to Boiler BSI Control System Sequence of Operation Sequence of Operation, Standing PilotVent Damper Note Less Vent GAS Valve BSI379 Honeywell VR8204/VR8304 Series GAS Valves BSI069 Robertshaw XI Start-up and Checkout 2423Standing Pilot Burner Flame For Your Safety Read Before Operating For Your Safety Read Before Lighting For Your Safety Read Before Lighting Position Indicator High Altitude Burners GASVALVEDETAIL-HONEYWELLVR8200ORVR8300STANDINGPILOT XII Service and Maintenance On a continuous basisOn at least a weekly basis On an annual basisPage Heat Exchanger Cleaning Procedure Xiii Troubleshooting Start END Start END Standing Pilot Ignition System Troubleshooting Chart Intermittent Ignition System Troubleshooting Chart XIV Parts Page KEY # Page Boilers only Page Appendix a Knockdown Boiler Assembly Instructions Before InstallingFIGUREA1 BASE, Heat EXCHANGER, Flue Collector Assembly Gas Valve Installation Figure A2 Jacket Installation Electrical Wiring Connections Complete InstallationFigure A3 Tapping Locations see Text for Tapping Uses Crown

BSI069, BSI345, BSI207, BSI172, BSI241 specifications

Crown Boiler Company is renowned for its high-quality heating solutions, with a diverse range of models designed to meet various residential and commercial needs. Among their popular offerings are the BSI series, which includes the BSI379, BSI138, BSI310, BSI276, and BSI103 models. Each of these boilers comes with distinct features, technologies, and characteristics that cater to different applications and preferences.

The Crown Boiler BSI379 is a powerful and efficient boiler designed for residential use. It features a stainless steel heat exchanger that enhances durability and improves heat transfer efficiency. The BSI379 operates on natural gas, providing a high thermal efficiency rating which helps to reduce energy costs. With a compact design, it can fit conveniently in various installations, making it a versatile choice for homeowners.

The BSI138 model is another excellent option for smaller residential spaces. It is equipped with advanced technology that allows for quiet operation and minimal environmental impact. This boiler also offers a straightforward control interface, making it easy for homeowners to adjust settings according to their heating needs. The BSI138's lightweight construction and small footprint allow for flexible installation options.

Moving on to the BSI310, this model is designed for medium to larger-sized homes. It features an electronic ignition system that ensures reliable start-up while minimizing gas consumption. The BSI310 also incorporates multiple safety features, including pressure relief valves and limit controls, enhancing user safety during operation. Its robust design ensures efficient heating even in the coldest months.

The BSI276 model is characterized by its sealed combustion design, which improves indoor air quality by preventing drafts and ensuring that all combustion air is drawn from outside. This model is ideal for energy-conscious homeowners seeking environmentally friendly options. Its high-efficiency rating translates to significant energy savings over time, making it a financially wise investment.

Finally, the BSI103 is an entry-level model that retains the quality and reliability associated with Crown Boilers. It is particularly suited for smaller homes or apartments and offers ease of use and maintenance. The BSI103 combines affordability with efficiency, providing a cost-effective heating solution without compromising on performance.

In summary, the Crown Boiler BSI series, comprising the BSI379, BSI138, BSI310, BSI276, and BSI103, showcases a blend of innovative technologies and features. With options suitable for various household sizes and energy needs, Crown Boiler continues to deliver reliable heating solutions that cater to modern homeowners’ demands for efficiency, safety, and convenience. Each model's unique characteristics ensure that users can find the perfect boiler to meet their heating requirements.