Totally OT - dishwasher problem - any advice?

[Penners]

Our Siemens dishwasher is playing silly games. Two symptoms:

1. The water isn't heating (it's a cold-feed only machine).

2. It starts its cycle with a pre-wash rinse, empties and then refills for the main wash cycle. It then just runs and runs and runs and..... eventually I end up cancelling the programme.

I've put my ohm-meter across the terminals of the water heater (it doesn't have a simple element, it's an instantaneous water heater unit - this one: http://www.espares.co.uk/part/dishwashers/siemens/p/1083/161/0/0/1068328/dishwasher-instantaneous-.html). I get open circuit. Obviously this suggests that the heating element inside the heater unit has failed. But I'm puzzled at the non-stop washing. Does anyone know whether this is normal - if the water doesn't heat up does the machine just keep running indefinitely, waiting for hot water?

Any ideas and opinions will be very much appreciated.

 

[Fred Drift]

Talking of notable historic Suffolk churches, this website is a great resource:

http://shct.org.uk/

 

[Gareth Hughes]

Our dishwasher is playing silly games... Any ideas and opinions will be very much appreciated.

Take the Pictionary off her and chain her back to the sink.

 

[Penners]

I shall report that to Mrs P, GH. Then you'll be sorry. :evil:

 

[Moo]

How old is the machine, Penners?

 

[Penners]

We inherited it with the house, Moo, but I believe it to be about 4 years old.

If it was a cheap one, I would think very hard about the advisability of buying a new water heater (£100!), as opposed to buying a new machine. But it's a Siemens, so should be high quality.

 

[Moo]

We had a similar problem with our (basic Bosch) dishwasher some time ago. Something to do with the timer thingy - the dial seemed to stick just before it had to open the soap-dispenser flap, so we had to stand in wait and then crank it round for a few clicks.
Eventually we solved the problem (can't remember how, but will ask the resident engineer if you like) and it still trundles on. Must be about thirteen years old by now.
I've vowed, however, when the time comes, to replace it with a Miele - the make that comes out top of all the Which? reports on reliability and that has a five-year guarantee. I believe that they also promise to keep spare parts in stock for ten years.

 

[Penners]

Thanks for the offer, Moo, but ours is one of those blasted modern ones that doesn't have any dials or suchlike. It's all controlled by an unseen computer. It hides behind a fake kitchen unit front, and is controlled just by five buttons in the top edge of the door. So you can't "wind it on" like you could with rotary programme dials.

 

[worms]

No experience of a Siemens machine but I had our Bosch to bits a while back. At ten years old it was surprising how much jelly had built up in a number of the tubes (it was like a firmer version of a well-reduced cold beef stock!). Is it possible that with only a cold wash, you have had one of the fill-level sensors blocked with this jelly? I had great difficulty clearing out one of the tubes in my machine but it seemed to make all the difference!

Could you open it after the cold rinse (you can probably hear the soap dispenser open) pour a bucket of hot water (or kettle of boiling water) and see if that makes it work? You might then know whether you have one problem or two!

 

[worms]

Our Siemens dishwasher...
it's an instantaneous water heater unit - this one: http://www.espares.co.uk/part/dishwashers/siemens/p/1083/161/0/0/1068328/dishwasher-instantaneous-.html).

Stock Number: ES1068328

Manufactured by Bosch
(Siemens is part of the Bosch Group)
Part No. 491756

Interesting!

 

[chuckey]

An "instantaneous" water heater must have an inbuilt "water" detector in it, probably has a diaphragm type switch to sense water pressure. no water, no heater, hence it measured open circuit on a meter. One problem I had with our Miele was that a fine filter in the incoming water hose connecter was blocked, low water flow & pressure upset the machine.
Frank

 

[worms]

Chuckey, I was just thinking about that and googling it!

 

[Penners]

Is it possible that with only a cold wash, you have had one of the fill-level sensors blocked with this jelly?

Thanks for those thoughts, worms. Actually I've spent most of today removing and cleaning the water feed filters, the matrix of water inflow and outflow pipes and the pressure tank. They were a little gunked up, but nothing serious. They're now fine, and the problem still exists .

The kettle of water idea is an excellent one. I'll try it tomorrow (too hacked off with it to do more today!).

Frank - thanks to you too, but I think my comments above cover the filter point. When you say "no water no heater" surely that doesn't apply in simply testing the element for circuit integrity. Isn't it true that any intact heating element will show a circuit when tested with an ohm-meter across the terminals?

 

[JoceAndChris]

Our dishwasher is playing silly games... Any ideas and opinions will be very much appreciated.

Take the Pictionary off her and chain her back to the sink.

:lol:
I don't have anything any more useful to add, except to commiserate, and say that life without a fully functional dishwasher is unthinkable.

 

[Flyfisher]

I believe most such appliances use a microprocessor-controlled timer/programmer these days; they are much cheaper and should be more reliable. The fact that the machine is following some sort of program suggests to me that it's not a controller problem - the program is permanently burned into the controller so is unlikely to suddenly start misbehaving so if it's working at all (which it seems to be) then it'll most likely work correctly (semiconductor 'chips' don't tend to partially fail, it's generally all or nothing).

However, the controller is dependent on various sensors to "tell it" what's going on within the machine. For example, there will almost certainly be a water-level sensor and part of the controller program will be something like "open water inlet valve, then wait for A", where "A" might be a signal from a sensor to detect a certain water level. There will be other sensors for water temperature and maybe different water levels etc - all the things that the controller would need feedback from in order to properly control the washing process.

From the description of the fault, it sounds like a heater problem. Dishwasher pre-washes are usually cold-only and it therefore makes sense that this part seems to be working correctly (implying the controller is also working correctly). The main wash will require hot water and it sounds as if the controller could be in a "switch on heater and wait until temperature is X" loop. If the heater doesn't work, the water temperature will never reach "X" and there's nothing tha controller can do but wait.

The idea of adding some boiling water might be a good way of confirming this. You might need more than a single kettle-full though.

It's unfortunate you don't know where the unit was purchased. Four years is not very long and I'd expect a water heater to last a lot longer and I'd be arguing that such a failure makes it unfit for purpose and should be repaired under warranty. This is less easy, of course, if you're not the original purchaser but might be worth a try if you can find a friendly local Siemens dealer.

Trying some suitable search terms might also reveal if this particular dishwasher has a known history of heater failures or if it's just a random failure.

I also agree with the other suggestions of checking for general 'gunge' around any sensors and also checking the sensor wiring connections. I once revived a washing machine by removing the various 'spade' connectors and replacing them - just the action of doing this can 'wipe' the connectors clean of any accumulated muck and/or corrosion.

Edit - Seems like you're already on top of some of these suggestions - that'll teach me to write shorter posts!

 

[worms]

Is this link of any use: http://www.keepingupappliances.com/...elp/how-to-test-a-dishwasher-thermal-cut-out/?
It mentions getting stuck in cycle if the thermal cut-out isn't operating properly.

 

[jocelyn plummer]

Kick it, swear at it, dump it and get a decent one. Actually, are you sure the previous owners had it from new?

Seriously, it's probably a circuit fault, how infuriating.

 

[Penners]

Thanks so much for that, FF. All very sensible, helpful stuff. And your reasoning about the running on endlessly seems to make complete sense to my simplistic view of such things.

I'm going to try worms' kettle idea tomorrow. I accept that a kettleful won't be enough to fill the machine, but I reckon if I add it just at the start of the main wash fill, and run on the 35 degrees programme, then the boiling water might bring the cold sufficiently up to temperature to satisfy the sensor. The machine actually uses surprisingly little water.

By the way, I've discovered that the machine is actually older than I thought. I inferred the age from the fact that the model number ends in ".../08". In fact, having checked our predecessors' kitchen installation paperwork, I find that it was fitted in 2006.

 

[Flyfisher]

I'm going to try worms' kettle idea tomorrow. I accept that a kettleful won't be enough to fill the machine, but I reckon if I add it just at the start of the main wash fill, and run on the 35 degrees programme, then the boiling water might bring the cold sufficiently up to temperature to satisfy the sensor. The machine actually uses surprisingly little water.

Yes, I liked worm's suggestion and would be trying it myself.

If a kettleful at the start of the main wash cycle doesn't stop the machine from stopping (!), I would add another one or more kettlefuls to be absolutely certain that the water temperature is above 35C. If the main wash does then process as it should, then I'd also let it run to the end just to confirm there are no other problems (you'll probably have a full load to wash by then anyway :wink: ).

Good luck.

 

[worms]

Are you sure that it drains between the pre-wash and the main wash? I don't think any of the dishwashers I use do this. The pre-wash water is heated and the dispenser opens at the start of the main wash cycle, but I don't think there is any draining or re-filling.