Vaillant ecoTEC plus 937 Instructions And Maintenance Instructions

Also see for ecoTEC plus 937: Operating manual Instructions for installation and servicing Operating manual

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Installation and maintenance instructions ecoTEC plus 0020031552_03468 Troubleshooting8.1 Logical fault finding procedureCarry out the following checks before the actual trou-bleshooting:• Carry out the tests to check electrical safety (see Sec-tion "Preparatory Checks on the Electrical System").• Check that the external power supply for the combiboiler is switched on and that there is a supply voltageof 230 V AC between the connections "L" and "N".• Check that the gas supply to the combi boiler isswitched on.• Check that the combi boiler has been properly purgedand that there is a supply pressure of 20 mbar theinlet to the boiler. (See Section "Gas Supply".)• Check that the heating system is filled with water andthat there is a pressure of between 1.0 and 1.5 mbar.Otherwise top up the system and bleed. (See Section"Filling the Heating System".)• Check that the stop valves in the flow and return linesof the combi boiler are open.• Check that the mains switch is set to "ON".• Set the temperature of the central heating to "Maximum".• Set the temperature of the hot water preparation to"Maximum".• Check that all external controllers are switched onand are demanding heat (if no external controllers arefitted, the connections 3 and 4 on the combi boilerterminal must be connected together).• Check that the burner anti-cycling time mode on thecombi boiler is not active.8.1.1 Status codesThe status codes which you can see in the display pro-vide information concerning the current operating sta-tus of the unit.Proceed as follows to display the status codes:Fig. 8.1 Display of status codes• Press the "i" button.The display shows the status code e.g. S.04 for the"Burner mode - heating".The status code display can be de-activated as follows:• Press the "i" button. or• Do not press any button for about 4 minutes.The current heating flow temperature appears in thedisplay again.Display MeaningHeating mode:S.0 No heat demandS.1 Fan runningS.2 Pump runningS.3 IgnitionS.4 Burner ignitedS.5 Fan and pump runningS.6 Fan over runS.7 Pump overrun timeS.8 Anti-cycling modeHot water mode (ecoTEC plus 800 models only):S.10 Hot water requestS.11 Fan runningS.13 IgnitionS.14 Burner ignitedS.15 Fan and pump runningS.16 Fan over-runS.17 Pump over-runWarm start mode/hot water storage tank charging:S.20 Pump runningS.21 Fan runningS.23 IgnitionS.24 Burner ignitedS.25 Fan and water pump runningS.26 Fan over-runS.27 Pump over-run timeS.28 Anti-cycling modeAll boilers:S.30 No heat demand from external controllers (terminal3-4 open)S.31 Thermostat knob of central heating switched off orno heat demand from an eBUS controllerS.32Heat exchanger antifreeze active, as fan speed varia-tion is too high. Appliance is within the waiting timeof the operation block functionS.34 Antifrost mode activeS.36 No heat demand from low voltage regulators (termi-nal 7-8-9)S.41 Water pressure >2.9 barS.42 Feedback from accessories module or defective con-densate pump blocks the burner operationS.53Appliance is within the waiting period of the modula-tion block/operation block function due to watershortage (flow-return spread too large)S.54Appliance is within the waiting period of the operati-on block function due to water shortage (tempera-ture gradient)S.96 Return flow sensor test, heat demands (hot water orheating) are blockedS.97 Water pressure sensor test, heat demands (hot wateror heating) are blockedS.98 Flow/return flow sensor test, heat demands (hotwater or heating) are blockedTable 8.1 Status codes (continuation see next page)8 Troubleshooting