Buyer's Guide to the Vibiemme Domobar Super - Page 7

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Marshall
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#61: Post by Marshall »

cannonfodder wrote:Let me elaborate. In the United States, every E61 machine I have used does not have a flow restrictor. The manufacturers do not put them in US bound E61's. My understanding is that they are commonplace on machines bound for other markets. I don't know why that is. That is why I point it out as a significant feature.

If someone can list any other US market E61's with factory installed thermosyphon flow restrictors, please do so. I know the Elektra, Isomac, Faema and Expobar do not have them installed for the US market.
Maybe you are thinking of a different kind of flow restrictor, but my Isomac Zaffiro shipped with a 1.0 mm gicleur. It typically produced a flow that was noticeably faster at the front of the brewhead, opposite where the flow entered the brew area. My pours started at the front of the screen and turned blonde there well before the rest of the puck.

I took the Isomac to Michael Teahan's shop to see if he had any ideas. He immediately opened one of the two hex nuts on top (I forget which one) and showed me the flow restrictor, which he said was large for an E61. He pulled it out with a tweezer and then dropped in several gicleurs of different sizes to see how they changed the pour (which they did, dramatically). We settled on an 0.5mm restrictor, and my problem was immediately and permanently solved.
Marshall
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HB
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#62: Post by HB »

Marshall wrote:Maybe you are thinking of a different kind of flow restrictor...
Dave is referring to a thermosyphon flow restrictor, which helps modulate the boiler heat transferred to the grouphead. Jon posted pictures and explanation in Installing thermosyphon restrictor on expobar office pulser and others elaborated specifically on the Super's in Size of Vibiemme Domobar Super E61 restrictor?
Dan Kehn

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cannonfodder (original poster)
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#63: Post by cannonfodder (original poster) »

Sorry about the confusion Marshall. I was not referring the group jet/gicleur, although it would be interesting to see what size gicleur the Super uses. The grouphead flow rate without a portafilter is unremarkable. It appears to be no faster or slower than your average vibratory pump driven E61 machine. I can measure the flow rate if someone wants that bit of information.

As Dan points out, I was referring the flow restrictor in the thermosyphon which helps control idle group temperature. My impression is that they are absent from US bound machines but present in most machines bound for other markets. Again, that is my impression based on little snippets of information I have read here and there. I have no substantiated proof of this and encourage anyone with contrary or confirming information to post it.
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cafeIKE
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#64: Post by cafeIKE »

cannonfodder wrote:I can measure the flow rate if someone wants that bit of information.
There's not much point. There's a fairly wide tolerance in the performance of the Ulka E5. Add in a few cumulative manufacturing tolerance and the number could be specific to the pump / machine / group combo you alone have.

<rant>
It makes damn fine espresso :!:
Bugger the numbers :wink:
</rant>

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#65: Post by HB »

Dan Kehn

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#66: Post by HB »

In addition to my role as color commentary contributor to this thread, I log thermometry data to confirm Dave's recommended brew temperature management techniques that he's developed using more holistic methods (namely "water dancing" and taste testing). This tag team approach speeds the review process and helps assure consistency across the Buyer's Guide series.

Below are a couple videos showing my early investigation using Eric's E61 thermometer adaptor (a production version of Dave's do it yourself model). The first video is the traditional flush and rebound, as described in HX Love. The target temperature is around 200F, which worked well for Rocket Reserve:

«missing video»

I've noted some HX espresso machines perform poorly with the "flush and go" technique, others will only perform well with flush and go, and some work either way if you twiddle the boiler pressure. My theory is that most of this preferred usage is attributable to the heat exchanger size and injector depth. The Vibiemme exhibits a classic E61 "HX hump" and seems to favor the traditional flush and [short] rebound approach.

After a few tries, I wondered if the Vibiemme would produce a flatter brew temperature profile using Eric's "flush and wait" approach. This alternative to flush and go / flush and rebound hasn't been talked about much in the forums, but in a nutshell, it's a slow reverse surf. I flushed down to ~198 and then watched the grouphead thermometer slowly rise to the target temperature:

«missing video»

I overshot the target temperature, but the overall profile is much flatter. It's a slow technique and only practical if you have Eric's adapter, still it may be worth updating the HX Love article to describe these three techniques (flush and go, flush and rebound, flush and wait).

Those who've watched flush videos with the thermocouple may notice the thermometer reacts more slowly compared to a type T thermocouple. It catches up by the last 5 or 10 seconds and the readings merge, similar to the curves shown in the thermofilter versus thermocouple adapter graph:



With the flush and wait approach, the readings track much more closely, maybe lagging by two degrees and catching up before the midpoint (sorry, when I made the video, I wasn't looking closely at the thermometer after I raised the lever). The ever industrious Eric has a type T thermocouple that's the same diameter for those who wish to swap between ultra-fast thermocouple responsiveness and the more aesthetically pleasing all-in-one thermometer / adapter. While I can readily nail the brew temperature within one degree with Valentina nowadays using a thermocouple, I think more Zen would be required for that level of consistency using the thermometer version. Then again, what would I do with my weekends without this extra challenge? Buy a double boiler and make espresso all day? :lol:
Dan Kehn

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#67: Post by cannonfodder (original poster) »

I have Eric's adapter installed with the thermocouple instead of the thermometer. It responds faster but I believe it initially reads high then settles in after the first 4-5 seconds. Once I get my thermofilter I can do a graph or two showing the delta between the two measuring points as well as a general temperature profile.

The wife is off to a wedding in Michigan this weekend, along with the camera so no video production this weekend.
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#68: Post by erics »

CF brings up an excellent point (amoungst many others) on Page 1 of this review when he says:
cannonfodder wrote:I have had the machine on for 4 hours now. I was wondering how hot the water in the reservoir gets as well as the cup warmer. The Fluke tells me the water reservoir is 91F and the cup warmer is a toasty 146F.
I have some 24" bulb thermometers laying around so I put one about midway in Anita's full water tank yesterday and noted tank temps of around 95 F after she was on for several hours. After a few more hours tank temp was approaching 100 F.

Note that the Vibiemme Domobar returns water (from the OPV) that is essentially at supply temperature back to the tank whereas, in direct contrast, the OPV on Quickmill machines like Anita and Andreja return water to the tank that has passed through the hx. Now this probably makes for very little temp difference if you are running a full tank but when the water reservoir is on the low side and you are feeding it OPV water at 200 F +, I might expect some unusual temperature/tastebud readings.
Skål,

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#69: Post by cannonfodder (original poster) »

That is interesting. I wonder why they put the OPV on the hot side of the system. All 3 of my machines vent on the cold side.

The Super also has a thin piece of insulation on the inside of the inner housing. That is there to help slow the warming effect that the large boiler has on the reservoir water.

The wife left the camera at the house, she must have taken a different one, or just forgot it. So I will be pulling some shots and posting some video's this weekend. It is supposed to be cloudy and stormy in Ohio, so I will have to stay inside and make drinks all weekend, darn. :roll:
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#70: Post by cannonfodder (original poster) »

The Vibiemme is cranking out some darn good shots. I have most definitely gotten into 'the zone' with the machine. My previous observations still stand. The Super is more than capable of producing some darn good espresso and its steaming ability is the best of any small boiler machine I have used. The flavors produced are a harmonic blend and equal to better than other E61 group machines on the market (thanks Caffe Fresco!). Here is an average shot from the machine. If this does not make your mouth water and heart patter, you must be dead.

«missing video»
Dave Stephens