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Assistance needed diagnosing a Duo Temp Pro


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Hello everyone. I haven't posted much on here but I am a long time lurker.

I am having trouble with my four year old Duo Temp Pro (the machine has been religiously descaled and cleaned, and never had any issues with it).

When the machine is turned on either to brewing mode, or steam/hot water mode, I am not getting any pressure (water/steam) through the group head and the steam wand. This issue developed rather suddenly with no specific tell-tale symptoms (change in pump noise, significant change in quality of pulled shots etc). One moring it just pulled one weak shot, then stopped producing pressure. "Dun, dun, dun" pump noise comes on when in either mode, no water/steam (NOT weak pressure...nothing at all is coming out)

Ordered a brand new Ulka EP5 pump and fitted it thinking the old one was kaput. Same problem.

How do I proceed from here? I've read some information about potential issues with the Over Pressure Valve, but how do I go about diagnosing the exact issue? To my knowledge this machine has no solenoid, correct?

Any advice to point me in the right direction would be much appreciated.

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  • 2 weeks later...

Some more information:

After fitting a brand new pump, I've disconnected the tube going from the OPV to the top of the boiler. I tested water flow from the tube into a cup and I am getting plenty of water when I turn on the machine. So, this tells me that there is no blockage from the water tank all through to the boiler intake. Picture attached showing the tube in question:

Any tips on how to proceed would be much appreciated. Is it scale build up causing the blockage? Something else to investigate? The boiler area looks more complicated, but if I know what the general steps are I can proceed with more confidence.

IMG_20200804_141715_2.jpg

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If it's going into the boiler as you say, its not the pump or the OPV, so it must be internal in the boiler?

(i don't think these have a expansion valve).

 

You are gonna have to remove the boiler and strip it down and find the blockage i think.....

 

 

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16 minutes ago, coffeenated said:

Thanks, that's what I figured! Are there any guides that you are aware of on how to strip down the boiler?

I dunno but if you sharpen your Google-Foo, there are parts diagrams and strip down videos etc that a DIYer could muddle through.

Sometimes you just have to undo stuff to get started :good:

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Blue_Cafe, thank you for your replies to my thread, I appreciate it. I should note that while my Google-Fu is sharp enough and I am comfortable using tools and taking things apart and reassembling them, the reason I asked is that one of the great thing about enthusiast forums like this one is that they distill knowledge and allow people to share and learn from past experiences. 

Anyway, I will start taking apart the boiler. If I manage a fix I will update this thread.

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13 minutes ago, coffeenated said:

Blue_Cafe, thank you for your replies to my thread, I appreciate it. I should note that while my Google-Fu is sharp enough and I am comfortable using tools and taking things apart and reassembling them, the reason I asked is that one of the great thing about enthusiast forums like this one is that they distill knowledge and allow people to share and learn from past experiences. 

Anyway, I will start taking apart the boiler. If I manage a fix I will update this thread.

Aye, Pictures of your own journey would be good, It would help future owners with their own problems!

It fustrates me to see somebody struggle with a problem, nly for it to be fixed and for them to not update on the solution :classic_laugh:  #denvercoder

 

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So I finally managed to fix my Duo Temp Pro. The culprit turned out to be a completely clogged boiler outlet hose where it goes into the grouphead assembly. The location of where it goes into the grouphead is marked below inside the yellow circle. The red circle marks the boiler inlet hose, which was all clear.

boiler.thumb.jpg.6b8b8beb186a6f3c98529b0994fc8522.jpg

The picture below shows how badly gunked up this hose was. This is the end that goes into the grouphead coming from the boiler (heat exchanger?).

clogged_hose.thumb.jpg.64e67c19eb0b6292123993f6561ccb9d.jpg

I took a few pictures of the top of the boiler to reference in case I forget where all the wires go after disassembly. I took off the screws holding down the wires, then the two bolts that affix the boiler to the top of the grouphead assembly. There is no need to completely remove the boiler as this will give you enough room to remove the retaining clip from the hose in question and remove it from the grouphead inlet. Half a minute with a dental pick and a bit of wire cleared all the gunk up.

cleaning.thumb.jpg.9333dc5ed15ab773af99845b754f6559.jpg

Reassembled everything and it's back to working as good as new. Gave it a full descale and backflush cycle and just enjoyed my first espresso from my DTP after several weeks of troubleshooting.

The old pump was working fine, but the new one I fitted (which I originally thought was the culprit) is much quieter. I guess it might have been time for a new pump anyway.

 

Edited by coffeenated
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Just now, DavecUK said:

You definitely need to review the water you are using in the machine. 

Yes, I have considered that. I am using tap water from a three-stage filter, but I will do more research on this. This machine sees rather heavy use (8-9 brew cycles/day).

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  • 3 months later...
On 21/11/2020 at 18:39, Mr_Paul said:

This is excellent I've got a very similar issue, so you didn't have to chip away at any of the build up in the boiler at all? Simply the dental pick on the end of the hose was enough? Was that the only blockage you found? 

Just the blockage at the end of that hose was the main culprit. I ran two back-to-back descale cycles for good measures after I cleared the hose blockage and everything seemed to be back to "as new" function.

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  • 4 months later...

Thanks so much for such a clear explanation of the fix! I nearly went into meltdown when my DTP stopped working - my wife suggested I just buy a new one to get over my misery - but your issue was precisely the same as mine and with your clear explanation despite my lack of skill in this area meant I was able to sort it  - and now it’s producing better coffee than it has for 2 years!

Edited by OweniteAdam
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On 01/04/2021 at 21:10, OweniteAdam said:

Thanks so much for such a clear explanation of the fix! I nearly went into meltdown when my DTP stopped working - my wife suggested I just buy a new one to get over my misery - but your issue was precisely the same as mine and with your clear explanation despite my lack of skill in this area meant I was able to sort it  - and now it’s producing better coffee than it has for 2 years!

Very pleased to hear the information I posted was useful to fix your machine!

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1 hour ago, coffeenated said:

Very pleased to hear the information I posted was useful to fix your machine!

It's an illustration of what happens if the machine isn't descaled often enough. Move on to the their machines with solenoids and some of that would have finished up in them so those act up. It's worse for people who froth milk regularly as that vaporises water and what ever was in it gets left behind. Some water in the coil may boil off at the end of a shot.

Sage engineers go around telling people to descale monthly. They could well be right and they often find themselves dealing with it on machines still in warrantee.

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