A.O. Smith 28 30 50 60 service manual Appliance’s heating cycle Protection for the appliance

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2

Functioning of the appliance

gis

2.3The appliance’s heating cycle

2.4Protection for the appliance

In this appliance the cold water enters the bottom of the tank via the cold water inlet n. The tap water, heated by the combustion chamber h and heat exchanger k, leaves the tank through the hot water outlet b. Once the appliance is completely filled with water, it remains constantly under water supply pressure. As hot water is drawn from the appliance, cold water is immediately added.

The air required for combustion is forcibly delivered to the burner q by the fan r. The gas is fed to the burner q via the gas control p. Thanks to the modulated supply of gas and air, the optimum gas/air mixture is always achieved. The special construction of the burner causes the mixture to form a vortex (the cyclone effect), before it becomes ignited. Because of this vorticity, ignition at the glow igniter t is improved, and the combustion efficiency is also optimised. Through the special design of the heat exchanger k, the flue gases are first led downwards via the combustion chamber, then upwards again via the heat exchanger, then once more downwards beside the water in the tank. In this process, the flue gases gradually become cooler. Because the cooled flue gases flow alongside the cold water below in the tank, they start to condense. This condensation causes latent heat energy to be released, which is transferred to the cooler water, and thereby increases the performance of the unit. The water of condensation yielded by this process is discharged via the siphon w.

The PU insulation layer x prevents heat loss. The inside of the tank is enamelled to protect against corrosion. The magnesium anodes i provide extra protection against corrosion.

For use during maintenance, the appliance has a inspection and cleaning opening l.

The entire appliance is controlled (and monitored) by theThermoControl d. The temperature sensor T1 g (in the top of the tank j) and the temperature sensor T2 m (in the bottom of the tank) measure the water temperature. These temperatures are sent to the ThermoControl. Based on these two observations, the ThermoControl calculates a net water temperature: Tnet. The value of Tnet lies between the temperatures measured at the top and bottom of the tank. As soon as Tnet falls below the set water temperature (Tset), the ThermoControl registers a ‘heat demand’. The gas control p is opened, and the gas is mixed with air. This mixture is ignited by the glow igniter t and the water becomes heated. As soon as Tnet rises above Tset, the heat demand ends, and the ThermoControl stops the heating cycle.

Both when registering and ending the heat demand, the ThermoControl assumes a certain margin. We refer to this margin as the hysteresis (see paragraph ’9.2 Setting the hysteresis’).

The ThermoControl monitors the water temperature and ensures safe combustion. This is achieved by:

•the Water temperature protection;

•the Gas control;

•the Fan;

•the Pressure switch;

•the Ionisation rod.

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Instruction Manual BFC

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Contents Release R.1.3 UK Your installer Liability CopyrightTrademarks More informationPage Table of contents GisStatus of the appliance Filling and drainingControl panel Starting up and shutting downMaintenance frequency Service programTroubleshooting MaintenanceAppendices IndexAbout the appliance IntroductionWhat to do if you smell gas Regulations Remark Target groups Maintenance Forms of notationSymbol Target group IntroductionOverview of this document Overview of thisDocument Chapter Target groups DescriptionGis Introduction Functioning of the applianceIntroduction Functional description of the appliance Appliance’s heating cycle Protection for the appliance Water temperature protection Gas controlPressure switch Ionisation rod Gas control Water temperature protectionPressure switch 3 FanVented installation Safety of the instal- lationUnvented installation Ionisation rodInstallation Introduction Packaging Environmental conditionsWater composition Humidity and ambient temperatureMaximum floor loading Working clearancesEnvironmental conditions Working clearancesTechnical specifications Plan and elevation of the applianceDime Description BFC Nsion DimensionsTechnical specifications Unit BFCVAC General Installation diagramGas data G30-30 mbar butaneInstallation UnventedCirculation pipe Water connections, Unvented Cold water sideHot water side Condensation drainageSee paragraph ’3.6.4 Condensation drainage’ Water connections, VentedGas connection See din FigureAir supply and flue gas discharge Dimension BFCAir supply and flue gas discharge Specification Description Concentric wall flue terminalConcentric roof flue terminal specifications Concentric roof flue terminalPreparation Mains voltage Electrical connectionPreparation Mains voltage Electrical connectionContinuous pump Extra on mode switch Tank onIsolating Transformer Program-controlled pumpChecking the supply pressure and burner pressure Connecting extra error signal Alarm OUTChecking the supply Pressure and burner ApplianceMain menu Conversion to a different gas category Conversion to a different gas categoryRemove the burner as complete assembly 13 Conversion of gas control Check the burner and supply pressure see paragraphInstallation Filling and draining Filling the appliance Filling unvented installationsFilling vented installations Filling the applianceInstallation diagrams F d c Filling and drainingDraining the appliance Draining unvented installationsDraining vented installations Draining the applianceGis Control panel Introduction OperatingPC connection Explanation of the icons ON/OFF switch of ThermoControlNavigation buttons Control panelIntroduction Operating modes Operating modes Error conditions Service conditionStatus of the appliance Error conditions Status of the applianceService condition Service conditionGis Introduction Starting up Open the gas valve see ’ .1 Installation diagrams’Starting up and shutting down Shutting downShut the appliance down for a longer period Shut the appliance down for a brief period OFF modeDisconnect the appliance from the mains Starting up and shutting downAppliance’s heating cycle Appliance’s heating cycle12 Ignition Main menu Notational convention for menu-related instructionsSetting water temperature during on mode Switching into on mode Setting the water temperatureSetting the water temperature via Setpoint Menu Changing the appliance’s standard week program Remark Week programme IntroductionStarting up and shutting down the week program Example Setting the switch-on timeSetting switch-off time Adding times to a week program Setting the water temperatureSetting program-controlled pump Week programmeDeleting times from a week program 20 Period added23 week program options Extra period Programming an extra periodSettings SettingsSetting menu language Setting day and time Displaying appliance specifications Remark46 Main menu Gis Displaying the error history Service programSetting the hysteresis Service program Setting the pump on/offSetting the service interval Displaying the appliance historySetting the display scroll speed Setting the display contrastSetting the backlight time Setting the display contrastService program Displayed errors TroubleshootingGeneral errors Troubleshooting table for general errors Symptom Cause Solution Remark Gas smell Gas leakWater leakage Symptom Cause Solution Remark Display is offSee appendix ’A.2 Electrical diagram BFC’ Insufficient or no hot Troubleshooting table for displayed errorsSymptom Cause Solution Remark Explosive ignition WaterS04 blocking error S02 blocking errorS03 blocking error S05 blocking errorS15 blocking error S13 blocking errorS14 blocking error Phase-sensitive. See ’3.10 Electrical connection’ F02 lock out errorAppliance specifications’ How to bleed air from the gas line, and measure the supply F08 lock out error F06 lock out errorF07 lock out error ’3.9 Air supply and flue gas discharge’Error F09 remains active in the event that the water F10 lock out errorRelease R.1.3 UK Release R.1.3 UK E03 blocking error C04 blocking errorE01 blocking error E04 blocking errorMaintenance frequency Determining service intervalMaintenance frequency Maintenance Remark Preparation for maintenanceStarting up Maintenance Cleaning the burner Descaling and cleaning the tankCleaning condensation water discharge Water-side mainte- nance Introduction12.4.3 Cleaning the orificeCleaning heat exchanger Remark Finalising mainte- nanceWarranty Certificate Warranty Certificate Appendices Week program cardElectrical diagram AppendicesWeek program card Release R.1.3 UK IX Index Index0306 IX Index
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