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Dualit DCM2 making steam and hot water but no flow through shower head.

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Hi CoffeeForumers,

I have a Dualshit DCM2 that my Dad gave me when it stopped working. It just made a horrendous sound when switched on and primed. In fact it didn't prime at all, trying three times before giving up. Very loud. I believe this to be because there was no water getting to the pump. I thought maybe the pump was on its last legs.

 

So, I stripped it down to get to the pipework. I cleaned out all the pipes with stiff wire and vinegar. Reassembled the device and started it up.

 

Sucess! I now get steam and hot water at good pressure and flow rate from the milk frother wand but when I switch to "coffee cup" mode, it has three goes at priming and then make a low volume, humming pump sound but nothing comes out of the shower head. Like the water is stuck somewhere. Another pipe? An internal blockage in the die-cast metal heating section?

 

I have cleaned the shower head in vinegar but it seems to me that the water isn't quite getting to that final section for some reason.

 

Assuming there's still a blockage somewhere the pipework attaches to in the die-cast metal of the heating section, I will be stripping down and repeating the process. But, before i do that...

 

Can the milk frother be working but the shower head not working for any reason other than pipe blockage? Could it be pump related at all? The pump goes quieter when the water is trying to go the shower head route.

 

I can provide pictures or youtube vid if that would help but maybe someone has some insight just from the description?

 

Strange that I got one process working (the steam wand) but not the main coffee making section. It seems most likely to be another blockage somewhere, I'm just not looking forward to taking all the screws out... again.

 

Thanks for reading, hope you can help!

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Could be a blockage, the pump will go quitter, or change pitch when it is under load.

 

I can't see a problem with vinegar except for maybe some odd flavours.

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Only poked into the pipework with some wire, then rinsed well. Vinegar did decalcify the pipe ends quicker than solely water - I tested it and chemistry won.

 

Unless i missed something?! Is vinegar the well-known nemesis of coffee machines?!

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Ah, I'll just run lots of water through it. I actually have another machine to use but can't bear to see Machine Heaven having to make room for one just yet. My Dad would be chuffed if he got it back working - i'm halfway there now!

 

Yes Dylan, i think you're right - it's the most obvious reason. I'll take a photo this evening when home, maybe someone can direct me to which pipe is the water-course for the shower head. There must be two different routes the water can take right?

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Hard to say, on something like the Gaggia Classic the boiler sits directly above the group, so in this case there is one pipe going into the boiler which fills it, and one out (from the top) which goes to the steam pipe. When the brew switch is engaged water is pushed at pressure from the boiler to the brew group, but as it is all one unit the 'pipework' is just a small hole within the cast frame of the boiler/brew group.

 

I would guess this is the rough layout of the Dualit but a picture may help confirm this. If so and a blockage is the problem them it may be a case of taking the boiler apart to get at any blockages within.

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So I took some photos.

 

Inspected the water course from start to finish. Water is sourced from the reservoir sucked up by vacuum into the pump whereupon it is directed by piping towards the boiler section.

Rear view.jpg

I presume there is some sort of expansion vessel inside the boiler section because water squirted into the entry point with a syringe seems to have less velocity when it exits from the other hole. Some sort of increase in circumference as it travels through the element housing so it can make steam?

 

Anyway, we know the boiler is good because the steam and hot water work just fine. Since there is only one route into the manifold from the boiler before the switch triggers a change in the path the water takes depending on whether steam or coffee is requested it has to lay between the manifold and the shower head metal block. Switch to steam it works, switch to coffee it chokes, sounds like it's struggling and strains the pump muting it somewhat.

 

 

 

Shower Head.jpg

The shower head block entry point is clear and syringed water drips at good flow rate through the head. Has to be before this, then. Took the pipe off between manifold and shower head block entry point - good flow, no blockage. Has to be manifold itself then!

 

Manifold Switch.jpg

Upon disassembly, the switch/selector insides seem ok so has to be the between the hot water entry into the manifold (left top entry point) and the exit to the shower head (right bottom exit point). Notice i've tilted the machine over a little and put vinegar in the manifold exit port to the shower head and it's pooling in there. Is this because the exit port is a one way valve out to the shower head?

 

To summarise, pump seems to be functional, boiler also. The problem seems to start and end at the manifold port to the shower head.

 

So how do i open up this blockage? I don't want to poke it too much in case i break the valve, so i'll stop now! Maybe I should take it off again and soak the whole manifold in some acetic overnight?

 

Is my deduction correct? Can anyone think of any other reasons?

 

Maybe this will help someone else troubleshoot their problem also since I would imagine most coffee makers are similar in design if not style.

 

Any input gratefully received. I'll have another look at the weekend when I get half a chance.

Manifold Exit 1.jpg

Final Section Test.jpg

Edited by 2b!=2b
Pictures didn't show up

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You have followed it through very methodically, and I would guess the same as you if I had been through the process myself.

 

That 'manifold' looks like its aluminium, we have just been discussing in another thread how citric acid will damage aluminium, so don't use anything citric based.

 

The other option is to try and apply some water at pressure to force any blockage out, not sure how you would do this however.

 

In regards to making steam the water will either be heated to well above 100deg in the boiler and steam piped from here, or it will pass through some kind of thermoblock which will be a snaked path for the water within a heated block of metal.

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Thanks for the advice from another thread Dylan - i'll not use any citric on the aluminium block then!

 

Will report back if I get anywhere with it.

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Tartaric Acid is what people seem to recommend for Aluminium descaling instead of Citric.


:coffee:Marcus

Isomac Tea + Nuova Simonelli Mythos+ VST 18g + Torr Brass Goldfinger Tamper

[ Gaggia Coffee Deluxe + Gaggia MDF Grinder + Gaggia 'Gold' Classic + Motta Convexed Tamper ]

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Turns out my thinking was correct. The blockage was finally cleared from the aluminium manifold by soaking overnight in a household descaling solution (not vinegar!). In the morning, when I poured running water through each of the ports, some muck came out of the port leading to the shower head!

 

One warning - when i reassembled I inverted one of the parts from the selector switch and inadvertently stopped both the shower head and the milk frother from working and it started leaking onto my conveniently placed towel. I immediately switched it off, took apart the selector switch housing, noticed my mistake, reassembled and it's all working ticketyboo.

 

When they were both blocked exits, the pump started to make the same low humming, over-strained sound on either selection - so this confirms my original supposition as to the nature of the problem.

 

Thanks everyone for looking and advising, much obliged.

 

I hope someone stumbles across this and it helps them fix their coffee machine too!

 

This thread can now be closed at an admins discretion - PROBLEM SOLVED!

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Great stuff, great feeling to fix something that was destined for the bin!

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Hi all! I have a strange problem with my Dualit esspressive. As soon as I turn it on it starts to pump immediately with the consequence that the water hasn’t had a chance to heat up! I’ve cleaned out the shower head to no effect so assume something is wrong with the selector switch. It does the same in the froth position and the cup position. Any thoughts anyone?

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