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I’ve got a problem with this machine, as per Bosch/ Neff. It starts to fill, then before there’s enough water, it begins to wash. I’ve replaced the heat exchanger and pressure unit as they were pretty gunged up, but still the same fault. All pipes etc. seem clear and valves seem to operate.If I add water manually it works fine, diverter changes, heats, until it needs to fill again. Customer said it was intermittant at first which led me to “blockage” probability. Any clues please
Re: Siemens SE26T251GB/07
Check the water level miroswitch as it is probably indicating to the PCB that the machine is full. In case you don’t know (apologies if you do) but the PCB controls the inlet valve, a timed fill in fact. The PCB calculates the time it takes from when the inlet valve opens until the fill level microswitch trips as the water drains out of the heat exchanger. And if that microswitch is faulty OR the pressure chamber jammed open the PCB ‘thinks’ it has filled and then shuts off the inlet valve.
Also, It won’t be the first time I’ve gone to a call where the previous ‘engineer’ has fitted the microswitch plug upside down!
Re: Siemens SE26T251GB/07
Does the heat exchanger actually fully fill at the start of the cycle ?
I’ve had faulty outlet valves cause problems where the water gets directed into the sump straight away rather than filling the heat exchanger .Re: Siemens SE26T251GB/07
I appreciate your comments but am no further forward. I’ve replaced the pressure chamber assy. which comes with new microswitches. The new heat exchanger fills to the brim but doesn’t release into the cabinet, so if I abort the cycle and reset it adds just a squirt then stops . I don’t think the machine has been touched before as customer was singing it’s praises, no problems for 6 years!
Re: Siemens SE26T251GB/07
Do you think it is possible you may have accidentally plugged in the top microswitch upside down?
Re: Siemens SE26T251GB/07
So the heat exchanger fills fully and then spills over into the pressure chamber . Does it then operate the pressure switch ? If it does , but then doesn’t dump the rest of the water from the heat exchanger into the sump , I’d still be looking at and checking the outlet valve on the water softener .
Re: Siemens SE26T251GB/07
Plug can’t be fitted upside down as it’s got a formed shroud. I think it can only be a sticking valve needle as the solenoid tests ok.
Re: Siemens SE26T251GB/07
chitts wrote:Plug can’t be fitted upside down as it’s got a formed shroud.
Ah one of them, so that blows that theory. I would go with Paul’s then and stick in a new outlet valve (166874) on the resin container.
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