A.O. Smith BFM - 120 manual Starting and running, Starting the appliance, Appliances heating cycle

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9 Starting and running

9.1Introduction

Topics covered in this chapter:

•Starting the appliance;

•The appliance's heating cycle.

9.2Starting the appliance

Start the appliance as follows:

1. Fill the appliance (5 "Filling").

2.Open (3.5 "Installation diagram") the manual gas valve.

3.Switch on the power to the appliance using the isolator between the appliance and the power supply.

4.Put the appliance in ON mode by setting the ON/OFF-switch on the control panel to position I.

5.Using the control thermostat (7.5 "Control thermostat"), set the desired water temperature.

If there is a heat demand, the appliance will run through the heating cycle (9.3 "The appliance's heating cycle").

9.3The appliance's heating cycle

The appliance's heating cycle is activated as soon as the measured water temperature (Twater) falls below the threshold value (Tset). This threshold value depends on the currently selected appliance operating mode. For example, if the appliance is in OFF mode (frost protection), then this value is 20°C. If the appliance is in ON mode, for example, then this threshold value can be selected, e.g. position 3 (± 60°C).

The heating cycle runs successively through the following states:

1.HEAT DEMAND;

2.WAIT;

3.PRE-GLOW;

4.IGNITION;

5.RUNNING;

6.WAIT.

The entire cycle is explained in the example below.

Note

The cycle has the same steps when frost protection is activated.

1.The control thermostat sensor measures the temperature. The water temperature falls below the set temperature of (for example) 60°C, causing the control thermostat to close. The burner control now detects a demand and starts the heating cycle.

2.Following demand, the wait period starts. This wait ensures that the ignition is safe. The wait period lasts approximately 15 seconds.

3.Once the wait period has elapsed (there is audible ‘clicking’ of the relay in the burner control), the PRE-GLOW starts.

4.After about 12 seconds (pre)glowing, the gas control opens and ignition takes place.

5.After ignition, the flame is detected and the appliance will be running. This means that actual heating has started.

6.When the water reaches the set temperature, the demand ceases. The gas control closes and the burner tray is extinguished. A new wait period of about 10 seconds starts.

7.At the end of this wait, the appliance enters the idle state, and waits until the water temperature once more falls below the set temperature.

With any subsequent heat demand, the heating cycle will resume from step 1.

Instruction manual BFM

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Contents Page Page Trademarks Read this manual carefullyLiability More informationGis Table of contents Performing maintenance TroubleshootingWarranty certificate Electrical diagramWhat to do if you smell gas Regulations IntroductionAbout the appliance Introduction Maintenance Forms of notation Target groupsSymbol Target group Chapter Target groups Description Overview of thisDocument Gis Principle Appliance Working principle of the applianceGeneral working Working principle of the appliance Appliances heating cycle Protection for the appliance Pressure switch Water temperature protectionFlame probe Protection DescriptionUnvented installation Safety of the instal- lationVented installation 3 T&P valveGis Air humidity and ambient temperature InstallationAir humidity and ambient temperature PackagingMaximum floor load InstallationWater composition Working clearancesTechnical specifica- tions Plan and elevation of the appliance Dimensions of the applianceDimens Description General and electrical specificationsBFM100 BFM120 Ion UnitDescription Unit Gas dataNatural gas G20 20 mbar LP gas data G30 30 mbar butaneInstallation diagram Installation diagramCold water side Water connections, VentedRecirculation pipe Hot water sideCirculation pipe Water connections, Unvented See C in the installation diagram 3.5 Installation diagramGas connection Circulation pipeAir supply and flue Introduction Installing chimney flue components for BFM 30, 50Subject Description Concentric wall flue terminal BFMConcentric roof flue terminal BFM 30, 50 Installing chimney flue components for BFM 100 C33 concentric roof flue terminal specifications BFM 30, 50Concentric wall flue terminal BFM100 M2000 MDV SCC C13 concentric wall flue terminal specifications BFM 100Concentric roof flue terminal BFM 100 Electrical connection 11 C33 concentric roof flue terminal specifications BFM 100Mains power Fan Alarm Off Connecting the mains powerGas control for BFM 30 through Checking the supply pressure and burner pressureGas control for BFM BFM BFM 30, 50, 80Conversion Conversion to a different gas categoryConversion to a different gas category Orifice replacementPage Conversion to a different gas category Filling Filling Draining Draining Draining unvented installationsDraining vented installations Gis Control panel ON/OFF switchExplanation of icons Control thermostatControl panel Burner control reset buttonOperating modes Error conditionsStatus of the appliance Status of the appliance Appliances heating cycle Starting and runningStarting the appliance Starting and running Shutting down Shutting down the appliance for a brief period OFF modeIsolating the appliance from the mains Shutting the appliance down for a long periodShutting down Control thermostat 7.5 Control thermostat TroubleshootingSymptom Cause Solution Remark Gas smell Troubleshooting general errorsWater leakage Explosive ignitionSymptom Cause Solution Remark Insufficient hot water Troubleshooting insufficient hot waterTroubleshooting No hot water Cycle Symptom Cause Solution RemarkPage Introduction Preparation for maintenance Performing maintenancePerforming maintenance Descaling and cleaning the tankWater-side mainte- nance 12.3.1 Checking the anodesIMD-0235 R2 Clean the orifices Clean the burnersGas-side mainte- nance 12.4.1 Checking the flue baffles Finalising mainte- nance13.1 General warranty Warranty certificate13.2 Tank warranty Conditions for Instal- lation and useWarranty certificate Electrical diagram Electrical diagram BFM Electrical DiagramOptional Components Electrical diagram Index Index 0306
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