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Alex Duetto playing up...
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Discussions > Espresso > Machines > Alex Duetto...  
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MrShades
Senior Member


Joined: 16 Mar 2010
Posts: 14
Location: Swindon, Wiltshire, UK
Expertise: I love coffee

Espresso: Izzo Alex Duetto II
Grinder: Mazzer Super Jolly
Posted Fri Jul 26, 2013, 1:51am
Subject: Alex Duetto playing up...
 

I've captured a couple of brief video clips - all of which are with a blind filter in the machine:

The first one shows the problem: http://www.youtube.com/watch?v=oz31whw5e04

This was one morning this week, when the machine was fully up to temperature but hadn't been used yet. The water in the tank was probably 1/3rd full, and it seems to be struggling to get water into the pump - as the pump sounds as if there's air in there somewhere. Certainly it had quite a way to go before any hint of a "low water alarm". I tried and tried again, but it woudn't settle.

Once this had been captured, I then filled the water tank to the brim with cold filtered water.

I almost knew that this would "cure" the problem, at least for the few minutes that it would take to pull a shot or two, so captured what happened as it 'recovers':

http://www.youtube.com/watch?v=BIgq7HRgiYs

You can tell that the first time it still struggles, but a few hisses and things later it settles, the pump sounds more normal and on the 2nd pull it hits 10bar on the manometer perfectly OK - as it should do.

At this point I pulled a double espresso and it all worked fine.

It seems that if I leave the machine for a while, hot, then the problem starts again - and often pulling a few "cooling" shots helps it to settle down to normal again.

All very odd... but I'm guessing that it's a valve sticking somewhere. My current guess would be to take the case off and have a good look and clean of the anti-backflow / non-return valve - wherever and whatever it is... and see if that helps. Certainly it seems like a similar problem to this one for an Izzo Alex (HX) on Coffeetime wiki: http://coffeetime.wikidot.com/izzo-a...n-return-valve

Anyway - all help or advice, or just thoughts would be very much appreciated.

Shades
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frcn
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frcn
Joined: 23 Dec 2001
Posts: 3,427
Location: Northern California
Expertise: Professional

Espresso: Vibiemme Domobar Double
Grinder: Mazzer Kony, Baratza...
Vac Pot: Hario, 2 Cory pots, 1 Cory...
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Posted Fri Jul 26, 2013, 6:13am
Subject: Re: Alex Duetto playing up...
 

The pump seems to be working fine. I wonder if there is an inlet screen on the pump (I have seen diagrams of rotary pumps which have that) which had a bit of crud on it?
When the pressure is low, does water come out of the pressure relief valve's bypass hose? That hiss sound is a clue as it is not normal. Is there any water coming out of the bottom of the group when the pressure was low? Could you tell where the hiss came from? That would be another big clue, even if you could identify the area generally.

Some other clues which might help with a diagnosis might come from how long the machine has been in service, how much it gets used, the quality (hardness) of the water being used, and what service it has had and at what intervals.

 
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MrShades
Senior Member


Joined: 16 Mar 2010
Posts: 14
Location: Swindon, Wiltshire, UK
Expertise: I love coffee

Espresso: Izzo Alex Duetto II
Grinder: Mazzer Super Jolly
Posted Sun Jul 28, 2013, 2:12pm
Subject: Re: Alex Duetto playing up...
 

A really good descale - with hot, strong citric acid - seems to have made a lot of difference.

Previously when I've descaled I've used a comparatively weaker cold solution.... but to help the 'pre boiler' water path (which is what I think was the issue - scale in the anti-backflow valve) I made a stronger solution using hot tap water (about 60c).

I ran it through the machine over a period of an hour or two, to make sure it had a good long descale - and it seems much better now.

Previously it would falter on the first pour of the day, and I'd had to run quite a bit of water through the system before the pressure stabilised properly and didn't fluctuate.  This morning, and for the rest of today, it's worked flawlessly.

I'll keep an eye on it, but it seems to have cured it.
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DavecUK
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Joined: 21 Sep 2005
Posts: 1,449
Location: UK
Expertise: I love coffee

Posted Sun Jul 28, 2013, 7:06pm
Subject: Re: Alex Duetto playing up...
 

MrShades Said:

All very odd... but I'm guessing that it's a valve sticking somewhere. My current guess would be to take the case off and have a good look and clean of the anti-backflow / non-return valve - wherever and whatever it is... and see if that helps. Certainly it seems like a similar problem to this one for an Izzo Alex (HX) on Coffeetime wiki: http://coffeetime.wikidot.com/izzo-a...n-return-valve

Anyway - all help or advice, or just thoughts would be very much appreciated.

Shades

Posted July 26, 2013 link

I wrote that article and to be honest I'm not sure that's the problem...the noise the pump makes when it runs dry and then gets water, is quite pronounced and fropm the Videos, yours doesn't sound like that. Also if the tests mentioned in the article are not positive on your machine (holding up the pump inlet tube and looking for a rising meniscus/waterline) it's almost certainly not the problem..

I would be inclined to suspect 3 areas....although you don't mention the specific model you have, or how old it is...which is not helpful. So this is a little guesswork (in decending order)

  1. The expansion valve may not be set right...this will show up as water flow either into the drip tray or into the tank (depending on the model of your Duetto)
  2. The expansion valve may be failing, or have drifted out of adjustment and need readjusting (this may depend on the age of your Duetto)...see above
  3. You may have an Inline water softening filter fitted (depends where you bought it from and when you bought it). If you do remove it.
  4. There may be a king in the inlet pipework to the pump. Open case and check.
  5. Pump might have a problem (depends on age of machine and usage or abusage).
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MrShades
Senior Member


Joined: 16 Mar 2010
Posts: 14
Location: Swindon, Wiltshire, UK
Expertise: I love coffee

Espresso: Izzo Alex Duetto II
Grinder: Mazzer Super Jolly
Posted Mon Jul 29, 2013, 1:34am
Subject: Re: Alex Duetto playing up...
 

Thanks for the reply and help Dave - much appreciated.

As I mentioned above, after a good descale with a strong, hot solution - and including all elements of the water-path (excluding the steam boiler as I hardly ever use it) - the Duetto has worked flawlessly since.

Previously it would struggle when pouring the first shot of the day, and if it had been left for any reasonable period of time (hours) between shots - but it's not shown any hint of water pickup/pressure issues since the descale on Friday pm.  Pump (and general operation of the machine) all sounds great, pickup seems perfect, pressure 100% stable and where it should be.

I guess, with it experiencing these issues when hot / been left standing for some time, it's more likely to be the expansion valve than the antiback-flow - so if I do end up in a case off / strip down situation I'll probably do both valves at the same time. Hopefully it's OK now though, and I won't need to.

FYI, it's a Duetto II - purchased from BB in Feb 2010 and running on Brita filtered water via the tank (although you help and advised when I purchased an RO system in 2010/11 I simply haven't got round to convincing the wife to lose a kitchen cupboard, hence installing it all and using it!)

Will keep an eye on it, obviously, but I think that the descale has sorted it - at least for the time being.

Thanks again for taking the time to reply, if anyone knows the right answer (or a good list of 5 possibles) to a Duetto problem it's you!

Shades
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