Miele Novatronic W931 WPS PC/'Tap' Light Flashing

[cgcrute]

For a while now our washing machine has occassionally stopped mid wash and the PC/'Tap' light flashes. We've put up with it but now it's getting worse, it took me 5 attempts to get a wash to work at the weekend. This machine was in the house when we moved in 10 years ago and has never gone wrong (other than the time my wife left the leg of a pair of jeans outside the machine which blew the door across the kitchen and ripped the rubber seal!!!).

I've done some testing today using a pressure gauge from Screwfix, the garden tap (about as close to the stop cock as you can get) gets 5-6 bar but the washing machine outlet hardly registers. I've checked the intake filter and that's fine.

Further testing indicates that the washing machine feed comes from the tank in the loft and not the mains.

Lack of pressure seems to be the culprit, but why? The feed was more than adequate for years! If it is the pressure (and not the machine, which is still an option) how can I restore it to a level the machine will work with?

Many thanks, in advance.

 

[zipper]

Miele stipulate min 1bar & max 10bar water pressure supply for this machine (most manufacturers use this range). If you have a lot less than 1bar on gravity feed then a booster pump might be your answer. However it is intriguing that the washer has functioned perfectly for 10 years then suddenly stopped working. All but the oldest Miele washers are fitted with what Miele call a "Waterproof system" (WPS). It works in the same way as an "aquastop" on a dishwasher. There are 2 solenoid valves in the grey box directly under the 3/4" connection that screws onto your water outlet. They valves are failsafe closed & only open when supplied with voltage via the pcb. It could be that one of the valves is mechanically jammed in the closed position, open circuit, or simply that they are not receiving voltage from the pcb. One way to test the WPS is to remove & test it independently of the machine. Or you could simply check if it is supplied with 230v in the fill phase. If you have 230v then the WPS has failed

 

[cgcrute]

Zipper,

Thanks for the reply, very informative.

It's funny you should mention the WPS thing, I've been wondering what it was! More of a mystery is how it gets its electrical feed, there are no wires running to it?? The WPS itself seems to make quite a bit of noise, like a buzzing noise, is this normal or could it be the cause of the problem or is it symptom of low water pressure?

Many thanks again,

Chris

 

[zipper]

You can't see the electrical cables to the WPS solenoid valves because they run between the ribbed outer sheath & the inner water hose.
These devices can & do fail, especially on older machines where the valves have cycled perhaps many thousands of times. Some WPS valves buzz audibly, some don't....but a slight buzzing noise is not a conclusive sign of failure. To confirm failure you would have to check for voltage at the WPS terminals inside the machine.....or remove the WPS & hotwire it.
My money is on a bad WPS....not low water pressure.

 

[cgcrute]

You can't see the electrical cables to the WPS solenoid valves because the they run between the ribbed outer sheath & the inner water hose.
These devices can & do fail, especially on older machines where the valves have cycled perhaps many thousands of times. Some WPS valves buzz audibly, some don't....but a slight buzzing noise is not a conclusive sign of failure. To confirm failure you would have to check for voltage at the WPS terminals inside the machine.....or remove the WPS & hotwire it.
My money is on a bad WPS....not low water pressure.

That's good news, wps sounds easier to resolve than the water pressure. I have to say it's not a slight buzzing, it reverberates through the house! We've been in the house 9 years and it was here when we moved in so it has seen some use!

Thanks for your input, it's calmed my fears that this will be hard to resolve!

I was considering getting a Miele engineer out (~£100 just to turn up and spend an hour on it), is it worth getting a cheaper local company out and specifying they replace the WPS (I doubt I'm up to doing it myself!)?

 

[Leccy758]

Last wps I got a quote from Miele was £86:00 for a dishwasher, luckily we had a good set of valves in the workshop on a broken pipe that we could splice in instead.

I tested it by cutting the wiring and fitting it onto an old normal fill valve just to prove it was opening the valve, then originally fitting the normal 10mm straight valve inside the wps cover with the original pipe jubilee clipped onto the valve and the wiring connected up.

Meant there was just one valve but it worked (later on I found the Miele valve set so changed it over)