NEFF S5456 Dwasher water supply switching on/off repeatedly

[stockwood]

Hi,

I have a NEFF S5456X1GB/12 dishwasher that has been pretty reliable until recently.

Now when I start the wash cycle, it sounds fine for the first 15 seconds or so but then appears to open the cold water supply and repeatedly closes/opens it every second for a good minute before moving on with the wash cycle. I haven't listened to the entire wash cycle but believe it is also doing it later in the cycle as well.

It's got the grey box on the inlet pipe which I understand to be the Aquastop and I've checked the filters in that and all appears OK.

I'm guessing that there may be a fault with the Aquastop or maybe a pressure/fill sensor somewhere but don't know enough about these things to know exactly.

Any help is appreciated.

 

[Leccy758]

I have seen some that do this when the water pressure is quite high.

The water comes in and fools the machine into thinking it is full (big sudden inrush) but when the water settles after a brief period it senses it is still low so adds a bit more, sometimes doing it a few times.

 

[zipper]

Maybe you could try to throttle back the supply via the tap or valve & see if that helps any? If your water pressure is too high maybe you need a reduction valve fitted. Max pressure for most machines is 10 bar.

 

[stockwood]

Leccy758/zipper, thanks for your comments.

I've restricted the flow through the valve I have connected to the Aquastop before, but it didn't seem to make any difference.

I'll give it another go but via the incoming mains stop valve as I can at least see how much the pressure has been reduced to by checking the sink taps. I'll let you know how it goes.

 

[zipper]

If throttling back the water supply doesn't help maybe you may have to consider changing the inlet valve. You could try taking off the left hand side-plate & take a peek at the pressure chamber for a possible build up of gunge. It is the device near the bottom with 2 micro switches on it.

 

[stockwood]

If throttling back the water supply doesn't help maybe you may have to consider changing the inlet valve. You could try taking off the left hand side-plate & take a peek at the pressure chamber for a possible build up of gunge. It is the device near the bottom with 2 micro switches on it.

Last night I reduced the mains pressure down to a trickle but it didn't make any difference to the frequency of the closing/opening. It seemed to extend the time that it did it for which is understandable as it would have been filling more slowly.

I've been having a look at the parts diagrams on the NEFF website so I see the Pressure Chamber you've mentioned which based on the descriptions for the parts seems to control the water level as well. I'll take it apart this weekend and see what's going on.

 

[stockwood]

Good news, found the problem and fixed it.

I took the left side panel off to expose the inlets/outlets, water reservoir and pressure chamber and fired it up to see what was happening.

I found that the water was filling the reservoir correctly, but when the water was released to flow into the main unit it was triggering the float switch on the pressure chamber which was in turn closing/opening the mains inlet repeatedly.

The chamber itself had some gunge in it, but the cause was the pipe that connects the chamber to the main unit. This was heavily gunged and probably had 5-10% the flow it should have done. This was causing the water to build up in the chamber and trigger the float switch.

I cleaned this pipe out thoroughly, dismantled the pressure chamber and cleaned that and also cleaned the outlet part of the water reservoir which was also gunged up.

It now runs smoothly.

Thanks for your help.

 

[zipper]

Good job