A.O. Smith BFM - 120 Safety of the instal- lation, Unvented installation, Vented installation

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2.5Safety of the instal- lation

In addition to the appliance's standard built-in safety monitoring, the appliance must also be protected by an expansion vessel, expansion valve, pressure reducing valve, non-return valve and a T&P valve.

The use of an expansion vessel, expansion valve and/or pressure reducing valve depends on the type of installation: unvented or vented.

2.5.1Unvented installation

With an unvented installation, an expansion valve valve and expansion vessel prevent the buildup of excessive pressure in the tank. This prevents damage being caused to the enamelled coating (in the appliance) or to the tank. A non- return valve prevents excessive pressure buildup in the water supply system. This valve also prevents water from flowing backwards from the tank into the cold water supply system. The pressure reducing valve protects the installation against an excessively high water supply pressure (> 8 bar). These components are fitted to the cold water pipe (3.6 "Water connections, Vented").

2.5.2Vented installation

With a vented installation, excess pressure is taken up by the open cold water head tank. The height of the head tank determines the working pressure in the water heater, which may not exceed 8 bar. The installation must also be fitted with a vent pipe from the hot water pipe, that opens into the cold water tank.

Ideally, the vent pipe should discharge into a separate tundish/drain or otherwise to the open cold water head tank. The water heater should also be fitted on the hot water side with a stop valve (3.7.3 "Hot water side").

2.5.3T&P valve

A T&P valve is only mandatory in an unvented installation. However, A.O. Smith also recommends the use of a T&P valve in vented installations.

A T&P (Temperature and Pressure Relief) valve monitors the pressure in the tank and the water temperature at the top of the tank. If the pressure in the tank becomes excessive (> 10 bar) or the water temperature is too high (> 97°C), the valve will open. The hot water can now flow out of the tank. Because the appliance is under water supply pressure, cold water will automatically flow into the tank. The valve remains open until the unsafe situation has been rectified. The appliance is fitted standard with a connecting point for a T&P

valve (3.7.3 "Hot water side").

Instruction manual BFM

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Contents Page Page More information Read this manual carefullyTrademarks LiabilityGis Table of contents Electrical diagram TroubleshootingPerforming maintenance Warranty certificateIntroduction About the applianceWhat to do if you smell gas Regulations Maintenance Forms of notation Target groups Symbol Target groupIntroduction Overview of this DocumentChapter Target groups Description Gis Working principle of the appliance General workingPrinciple Appliance Working principle of the appliance Appliances heating cycle Protection for the appliance Protection Description Water temperature protectionPressure switch Flame probe3 T&P valve Safety of the instal- lationUnvented installation Vented installationGis Packaging InstallationAir humidity and ambient temperature Air humidity and ambient temperatureWorking clearances InstallationMaximum floor load Water compositionTechnical specifica- tions Plan and elevation of the appliance Dimensions of the applianceUnit General and electrical specificationsDimens Description BFM100 BFM120 IonLP gas data G30 30 mbar butane Gas dataDescription Unit Natural gas G20 20 mbarInstallation diagram Installation diagramHot water side Water connections, VentedCold water side Recirculation pipeCirculation 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 thermostat ON/OFF switchControl panel Explanation of iconsControl panel Burner control reset buttonError conditions Status of the applianceOperating modes Status of the appliance Starting and running Starting the applianceAppliances heating cycle Starting and running Shutting the appliance down for a long period Shutting down the appliance for a brief period OFF modeShutting down Isolating the appliance from the mainsShutting down Control thermostat 7.5 Control thermostat TroubleshootingExplosive ignition Troubleshooting general errorsSymptom Cause Solution Remark Gas smell Water leakageSymptom Cause Solution Remark Insufficient hot water Troubleshooting insufficient hot waterTroubleshooting No hot water Cycle Symptom Cause Solution RemarkPage Introduction Preparation for maintenance Performing maintenanceChecking the anodes Descaling and cleaning the tankPerforming maintenance Water-side mainte- nance 12.3.1IMD-0235 R2 Checking the flue baffles Finalising mainte- nance Clean the burnersClean the orifices Gas-side mainte- nance 12.4.1Conditions for Instal- lation and use Warranty certificate13.1 General warranty 13.2 Tank warrantyWarranty certificate Electrical diagram Electrical diagram BFM Electrical DiagramOptional Components Electrical diagram Index Index 0306