# Izzo Vivi Thermosiphon Restrictor



## peterportugal (Nov 19, 2019)

Hi All,

I am a new member who has viewed many informative posts here recently. I have owned for several years an Izzo Vivi bought from ebay. Gradually as faults developed, and I had to address them, my knowledge of the machine has improved. Rather than repairs I am now looking at some modifications and first up is a thermosiphon restrictor.

The machine is in domestic use and may go for an hour or two in between shots. I bought one of those digital brewhead temperature gauges and this tells me the idle temperature climbs to 105DegC after an extended period. I have to flush A LOT of water through to bring this back down to 96 DegC. The mrs & kids like the cappuccinos so I can't turn the pressure stat down too much.

I am considering installing a restrictor in the thermosiphon supply. I wondered if anybody has done this before, where they bought the parts, where they fitted them and what the results were.

The machine was UK supplied via BellaBarista originally.

Thanks

Peter


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## DavecUK (Aug 6, 2013)

I hope this helps you out a bit and I do have some hydraulic diagrams of the machine somewhere if you need them.

The Vivi was one of the early machines I tested around 14 or 15 years ago...I'm sure I did temperature testing on it as it was around the time I made the kit I needed to do it better. I'll try and gig out my old notes and the instructions I wrote for the machine regarding cooling flushes...because I tested that as well. What boiler pressure are you running?

Without a photo I don't know what model you have but they didn't change much, I wen through my Archives and found the user guide I wrote all that time ago as you probably don't have it. My advice for cooling flushes after testing was:

Run 4oz of water (20 sec) through the
group for the first in a series of shots,
after that (2oz or 10 sec) before each
subsequent shot. If machine has been
idle for a long time increase this to 5 or
6 oz (30 sec). Do these cooling flushes
with no portafilter loaded

So yes the water debit is heavy but not excessive (especially for those days), I can't remember if the times were exact, but it's the volume of water you need to flush. I seem to remember that with a restrictor you would have problems with sour shots, unless you had a very specific usage regime. Even then the HX construction was such that you run the danger of being too cool after a flush (and you would still have to do a flush). My recommended pressure settings are below (the commercial use bit is if it got more use in a very small cafe or something) e.g. 6 shots in a row or whatever.


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## peterportugal (Nov 19, 2019)

Hi Dave,

I was hoping you would reply, so may thanks ! It is identical to the one in the BellaBarista review referred to as the Vivi MkII.

I have the pressure stat set at 1.1 to 1.2 bar which is in line with your recommendation for domestic use.

Maybe trusting the temperature sensor is not an ideal solution but I am having to do at least 6oz, I have 5.5oz cups and it takes more than one. I usually leave the portafilter in place so I would be interested to know why you recommend to leave it out.

I get the impression from your reply that the machine (as shipped) would not have a restrictor fitted?

Regards

Peter


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## DavecUK (Aug 6, 2013)

Only to leave it out when flushing so you don't have to dry it...

If you are having to flush more than 6Oz after a very long wait between shots....that's not sounding right you are talking a flush of more than 180 ml... I can't speak for the accuracy of the temperature sensor you have fitted to the group as I don't use them. I measure temps 3 mm inside a simulated coffee puck.


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## peterportugal (Nov 19, 2019)

Hi Dave,

Thanks again for your feedback. I will give it another try when I am back home and monitor the group temperature vs flush volume a bit more carefully. I have just ordered two restrictors for a Lelit machine as they were only a euro each, 2.5mm and 2mm. I might try these, if they do adversely affect the shots I can always take them out.

Do you recommend bothering with the adjustment of the OPV? I put one of those portafilters in with a pressure gauge and it indicated 12 Bars but it could possibly be higher as there was some leakage from the group head gasket.

Thanks

Peter


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## DavecUK (Aug 6, 2013)

peterportugal said:


> Do you recommend bothering with the adjustment of the OPV? I put one of those portafilters in with a pressure gauge and it indicated 12 Bars but it could possibly be higher as there was some leakage from the group head gasket.


 Yes I do recommend adjustment of the expansion valve. The Vivi had a nice good quality and very adjustable expansion valve. Just remember to take (water expansion when heating) out of the equation if you can...as that can add a false pressure rise after the pump pressure is reached. So a totally cold machine is ideal, because it's an HX you can leave the heating elements on because there won't be enough heat in the first few minutes to affect anything. Aim for 9 to 9.5 bar.

The other thing you can try to reduce the size of the cooling flush is to split it into 2 smaller equal parts with a small pause in between.


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## peterportugal (Nov 19, 2019)

Dave,

Thanks again for your help, I will adjust the OPC as you describe.

To be honest the flushing isn't that much of a hassle for the 5 or 6 times a day I have to do it. It's the fact that I am chucking away the thick end of a litre of bottled water each day which seems wasteful.

Regards

Peter


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## kozesluk (Apr 28, 2019)

most standard home-use E61 clone machines benefit from 2.5 to 3 mm restrictors. it is always just a plate (I've even seen teflon discs with hole in the centre - worked well enough) or another suitable piece of metal with a hole. you might end up drilling the 2.0 mm up to 3.0 mm and use that if you find that 2.5 mm is too small for your particular machine. but this is hard to tell without SCACE and measurement of the extraction temperature profile - too small jet with higher boiler pressure will inevitably end up in correct 'idle' temp and initial shot temperature, but the profile will be declining and the machine will struggle with subsequent shots (declining temperatures on them, too much dependent on the pace).
oh, and always place the restrictor in the upper HX arm. its second purpose aside from restricting the thermosyphon action is to make the lower HX arm the preferred water source during the extraction (it's always mix of both).

my ideal setting would be to have a machine where you don't need to flush at all. I have achieved that in old Grimac La Uno with 3.2 mm restrictor and boiler set at 1.25 Bar. extraction measured by SCACE-clone at 94 C, short flush (50 ml) just made the temperature profile more "flat" throughout.


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## GazRef (Dec 30, 2019)

DavecUK said:


> I hope this helps you out a bit and I do have some hydraulic diagrams of the machine somewhere if you need them.
> 
> The Vivi was one of the early machines I tested around 14 or 15 years ago...I'm sure I did temperature testing on it as it was around the time I made the kit I needed to do it better. I'll try and gig out my old notes and the instructions I wrote for the machine regarding cooling flushes...because I tested that as well. What boiler pressure are you running?
> 
> ...


 Thanks to the search button and this great info you saved me a post. Just wanted to say thanks.


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## peterportugal (Nov 19, 2019)

Guys,

I finally got round to executing this work. I discovered that the restrictors I bought for a Leilit machine were not compatible. These would fit in a tube with 10mm internal diameter whereas the tube on my Izzo was 8mm (the tube from the Boiler HX to the upper connection on the E61 group).

Does anybody know of any sources of compatible restrictors?

I also discovered that my OPV was non functional as it had been assembled incorrectly. That is now sorted and with it correctly set at 9.5 Bar it has made a big difference.

Regards

Peter


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