Getting started with the Vibiemme DoubleDomo Super - Page 3

[1st-line]

I got mine about a month ago, but have not really had the time to fully delve into the details of the machine. With the many questions I'm sure we will all be sharing in the next few months, the one thing that I have noticed is that the steam pressure (pre-set to 1.5 bar) drops off to 0.5 and then zero pretty quickly. I can really only steam single cappuccino amounts of milk maintaining a 1 - 1.5 pressure level. If I try to do two latte's at once it is takes much too long and the steam pressure is at zero for the latter part of the process.
Anyone else experiencing this? Should I be adjusting the steam pressure-stat for this?
THANKS!

Hi All,

After 2 days of working with our programmers, etc to resolve server crashes, software crashes, etc... I just had some time to add some feedback on this as I just pulled out the test unit formerly slated for HB and now slated for the SCAA show in MN.

To address the steam concern, I came accross the following conditions and results...

a) Steam boiler pressure was initially set at 1.9 bar. Machine fully warmed up to operating temp for both boilers.

b) Started with 12 ounces of cold water from faucet. The first instance instance had 2 minutes of steaming capability where it brought the water to a boil. The needle did nose dive to about 1 bar and then went and hovered near .4 to .5. until the water refill kicked in at 2 minutes and 5 seconds - at which point the steam pressure gauge needle nosedived to zero. In the second instance, the water came to a boil in 1 minute and 45 seconds. Again, the steam zeroing out at about 2 minutes.

c) In both instances, the recovery for the steam boiler was about 1 minute to 1 minute and 10 seconds.

d) In both instances, i did not measure the initial temperature of the cold water. our inventory shows 300 thermometers in our warehouse, and since we just moved, I can not find one! however, i did start steaming when the steam heat cycle was at the max of 1.9. The min level was about 1.5 to 1.6.

e) The steam is dry (similar to Vibiemme's HX machine).

I have already emailed Vibiemme about these results. i do not think there will be a problem bringing up the steam boiler bar pressure to 1.9. I am not sure where the safety valve on the steam boiler kicks in to release steam. So, please do not go higher than 1.9.

Now, results can vary from machine to machine as voltage (in your outlet can range from 100 volts up to 125 volts on a standard outlet), ambient temp differences, steaming pitcher temp differences, water temp differences, etc can impact these results.

It is now 9:22 pm est, and I need to get out of this office!

[1st-line]

If you use a thermostat for the steam boiler the heating element won't likely turn on the instant you open the steam valve and you might find the steaming abilities slightly reduced.

Ira

I will confirm that the machine will have a slower reaction tiime to turn the steam boiler's heating element 'on' with a thermostat.

[networkcrasher]

Tore the machine apart a bit more tonight to fix the Sirai bracket and took a few more pics.

[networkcrasher]

[networkcrasher]

[networkcrasher]

[trakt140]

The german reseller Systermann is using 2.5 bar for the steam boiler, so this shouldn't be an issue.

http://www.kaffee-netz.de/marktpl...-2.html#post197203

[CafSuperCharged]

I will confirm that the machine will have a slower reaction tiime to turn the steam boiler's heating element 'on' with a thermostat.

I overlooked the fact the steam boiler is in the physics phase of saturation. As long as there is enough steam to remain saturated temperature will probably hardly drop, rendering thermostat controlled steam boiler inappropriate.

Regards
Peter
Netherlands
Europe

[CafSuperCharged]

Tore the machine apart a bit more tonight to fix the Sirai bracket and took a few more pics.

Based on earlier comments, I would say the small boiler is the steam boiler and the large one the brew boiler.
For one thing this might be an explanation, but at this stage wild speculation.

Other than pressure, there is another variable I would relate to steam capacity, still: steam boiler water level.
I would think a high level leaves less volume (cubic centimeters) for steam, but, considering someone in these fora uses avogadro for web name, I might be taught a lesson in physics here, proving this is not so relevant. Still, steam boiler water level would be relevant in another way: re-heating response time to pulling steam. Would a larger amount of (liquid) water - higher level - provide more thermal buffer? I guess so, but it might take more time, once temperature dropping, to reheat the water to steaming temperature and related pressure.

Going back from this discussion to the machine's innards: the Cigar brainbox shown in the photos connects to the level detector (Liv) and pump (Pompa). Following the Liv wire to the level detector on the steam boiler you get to a metal insert on top of the boiler with the sensor in the middle to which the wire connects. I believe that level meter can be adjusted for the depth of the actual sensor. (somewhere else I read a warning about replacement of the wiring harness and taking care not to change the depth of the sensor which would easily change when pulling off the wire on it.)
All these Italian machines are system integrated generally from in-sourced prefabricated parts. They will do alternating series of their models. In the case of my own QM espresso machine, a new employee had assembled the water tank (magnet float, guiding channel, stop to keep magnet in front of solenoid switch when enough water). He was not aware the height position of the screw to keep the guiding channel in place was important - the machine did not come on with the water tank filled more/less than exactly the position of the solenoid.

In other words, did they maybe do a series of these machines with the level sensor in too deep or not deep enough? And are you trying to work around that by raising the pressure?

Regards
Peter
Netherlands
Europe

[stefano65]

Safety valve are calibrated to open at 1.8 - 2 bar ( depending on which one you have ). The compact style safety valve ( with blue sticker in top) is calibrated to open at 2 bar.

I do not recommend adjusting any pressurestat any higher then 1,5-1.6 ever

[jasonmolinari]

Am i the only one who things VBM should have already put the offset into the PID display?
I'm looking forward to the review of the machine, but i must say that between that, and the steam boiler issues i'm a little disappointed. But i may be reacting too soon.

[networkcrasher]

In other words, did they maybe do a series of these machines with the level sensor in too deep or not deep enough? And are you trying to work around that by raising the pressure?

Jim and I talked about this too. As you can see from the photo below, to the far right is the water level sensor, and it's pushed all of the way into the boiler. It can not go any deeper. We had thought about using more water, but I haven't tested that far yet.

[cafeIKE]

Am i the only one who things VBM should have already put the offset into the PID display?

For my 2p, they could have hidden the display. I deliberately put the PID under my machine so I don't have to look at the numbers. 99% of the time, I have the blank cap on Eric's TC adaptor. Once the machine is dialed in, taste is the only indicator necessary.

Quoting cannonfodder, "It is just coffee." and "Don't over complicate the process."

[CafSuperCharged]

Jim and I talked about this too. As you can see from the photo below, to the far right is the water level sensor, and it's pushed all of the way into the boiler. It can not go any deeper. We had thought about using more water, but I haven't tested that far yet.

Yep - the picture makes clear it cannot go any deeper.
I must assume that the sensor, actually being a conductive rod, may be available in different lengths.
What if the person who assembled this series took the wrong length? Or the vendor that shipped them to VBM sent the wrong part nr.?
Still, you might be able to test the hypothesis of a problem with the water level sensor.
If the problem is caused by too much water and too little headroom (steam) relative to the capacity of the heating element, then bringing the sensor further up/out should worsen your observed problem.
If the problem is somehow (but I would not have logic available, other than part of the heating element could be out of the water, but very unlikely) the water level is too low, then the problem would go away when bringing the level sensor up.
You would want to talk to your supplier, if a) you could void guarantee, b) if tightening requires a certain maximum torque to be applied.

Another thought: does your water contain enough minerals/electrolytes to be conductive enough and activate the level electronics properly?

Regards
Peter
Netherlands
Europe

[downunder]

Am i the only one who things VBM should have already put the offset into the PID display?
I'm looking forward to the review of the machine, but i must say that between that, and the steam boiler issues i'm a little disappointed. But i may be reacting too soon.

Maybe not the only one, however, although I at first shared these concerns I now actually prefer the PID arrangement - the offset will vary somewhat with ambient temperature - so knowing it is roughly 8-10 degrees Celsius allows you to tweak - also it seems you do need to run the steam boiler around 1.8 bar - at this setting it way outperforms my Livia 90 which I had to dial down to 1.1-1.2 to get the extraction temps where I preferred them - and the Livia still produced lovely microfoam (with a 3rd party 2 hole tip) although with only about 5 or 6 oz. of milk at a time - so you would probably be very happy with the DoubleDomo - it is quite beautiful.

[cafeIKE]

Steam production and foaming milk successfully rely on several interelated factors.

It's the velocity of the steam that produces the foam.
The velocity of the foam is related to the hole diameter, steam volume and pressure.

More water, i.e. higher level will produce more steam when the pressure is released. The potential volume of steam is directly related to the water volume and temperature above the local boiling point at the boiler pressure. The down side of a high water level is the initial volume of steam is reduced and the pressure drops more rapidly when the valve is opened, reducing velocity.

The capacity to continually produce steam is related to the heat input, the input water temperature and the pstat setting. The water level has no effect. Water level affects how quickly the system can recover once the valve is closed.

The water level probe can be adjusted by loosening the small upper nut slightly and pulling up on the probe.

I run distilled water in my boiler and have NO problem with the level sensor shutting off the pump.

A pressure stat is the ideal control for a steam boiler as its response is instant upon pressure drop. A thermal probe will lag behind the valve opening by several seconds. This factor was one of the reasons I put the pstat back in to control steam boiler pressure on my PID HX Vibiemme Domobar Super. Details in HX Heaven or 1½ Boiler

[CafSuperCharged]

Ian, it looks like you answered the questions here. Thanks. I rest my case.

Regards
Peter
Netherlands
Europe

[1st-line]

Am i the only one who things VBM should have already put the offset into the PID display?
I'm looking forward to the review of the machine, but i must say that between that, and the steam boiler issues i'm a little disappointed. But i may be reacting too soon.

Jason,

Temperature management, control, and readings are a science in itself. Upon discussions with not only Vibiemme, but other manufacturers as well, a programmed offset into the PID display will not be accurate.

It may get close, but it will still be off the true target. One of the main reasons is that the machine will be placed into different environments with different airflows, different ambient temps, different voltages, etc that can affect the true offset.

[1st-line]

Safety valve are calibrated to open at 1.8 - 2 bar ( depending on which one you have ). The compact style safety valve ( with blue sticker in top) is calibrated to open at 2 bar.

I do not recommend adjusting any pressurestat any higher then 1,5-1.6 ever

Stefano,

I was running our machine at 1.99 bar today with almost continuous steam. I say 'almost' because when the autofill kicks in, it simmers down a little, but the steam does not stop. And, with the steam wand still open, it recovers to about 0.5 bar pressure, until the autofill kicks in and simmers it again. Even when it simmers, there is still steam coming out.

Safety valve has not released. I am awaiting Vibiemme to determine the safety valves cut off. I am also awaiting their reply to see if another 2 hole tip with smaller holes is available, or a one hole tip which could improve the results for those who were more optimistic about the steaming performance.

[stefano65]

Hi Jim
funny we have to talk on a forum
the safety valve with the blue sticker in top is calibrate for 2bar
they might have a .2 of plus of minus
see image of scanned document attached
the traditional looking one they have a 1.8 calibration