Vibiemme Domobar Junior Double Boiler- Thermostat Performance

Need help with equipment usage or want to share your latest discovery?
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sasquatchgeoff

#1: Post by sasquatchgeoff » Mar 14, 2011, 10:16 am

As promised, a thermostat performance update on my new Vibiemme Domobar Junior Double Boiler:

Received my digital thermometer and fitting adapter rather quickly (2 day turn-around) - ordering from "the source" has its benefits. After a couple of days of tweaking for Hair Bender beans (92-93c) I can confidently state that t-stat issues (large brew boiler temp fluctuations) with using the steam boiler/brew boiler simultaneously have not appeared during my use. Yesterday, I left the machine (both boilers) on all day and doing so resulted in hotter, (94-95) yet consistent brew boiler performance. Finally backed the t-stat to the position that I received the equipment (Stefano marked with a sharpie) and get solid 92-93 temps during brew 86-87 idle.

Whew, I am really glad for this. Apparently the "issue" experienced by other members is resolved, at least on my machine. When I get time (in school finals right now) I will log a day's worth of temps on an excel spreadsheet and post. Glad I can wait for a PID mod until after warranty period. Stay tuned.

Geoff

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sasquatchgeoff

#2: Post by sasquatchgeoff » Mar 16, 2011, 5:50 pm

New update:
Noticing a performance issue when using the steam boiler under certain conditions.

1. Normal scenario: Machine is connected to a timer that turns brew-boiler only on at 5 AM. By the time I get up at 6, I flip the switch on for the steam boiler, and then start loading and tamping, the grouphead is nice and toasty at 88. Pull my shot at a perfect 92.5. Steam is ready, foam milk and make superior latte for my wife. Then I repeat the pulling and steaming for myself - no issues. Life is good. Turn off the steam boiler and go to work. Machine turns off via timer at 11AM (just in case the wife wants to pull a shot).

2. Random scenario: It's a "day off" kind of morning. Turned the machine off the night before by mistake. Wake up late - Turn on BOTH boilers, walk around the corner for a bagel, wait 45 minutes for the boilers to warm up. Come back and check temp on brewhead - 12 degrees below normal! Start flushing brewhead to bring temp up. Start flushing through hot water wand to help brew boiler t-stat forget that it has a hot steam boiler sitting next to it. Takes and additional 30 minutes and an extra reservoir of water for brew temp to get up and stable for brewing.

So, the moral of the story is, wait until the last minute to turn the steam boiler on, and always turn it off when not in use. That puppy heats for steam pretty quick, so this is not a major inconvenience, but still worth mentioning. Also, another note to self - start researching PID mod.

All of this notwithstanding, I still love the machine.

Geoff

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erics

#3: Post by erics » Mar 16, 2011, 6:17 pm

Geoff -

At the very bottom of each thread there is a link you can "click on" to subscribe/unsubscribe. I would suggest you subscribe to this thread - Install a PID on my Vibiemme Junior DB? as there will be new & interesting developments to report soon.

Applying a PID to the Vibiemme Junior is "duck soup" with the only hassle being the location of the PID controller itself.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

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sasquatchgeoff

#4: Post by sasquatchgeoff » Mar 16, 2011, 6:26 pm

Thanks Eric,
I look forward to such projects. In the meantime, my coffee demands allow me to run a "finessed" operation in order to make good beverages. Its all in the timing.

Now when I get a house full of people who all want coffee, it will be a different story.

Geoff

expy98

#5: Post by expy98 » Mar 16, 2011, 7:56 pm

Geoff,

so the moral of your story is to do all the brewing you need to do quickly, however
many shots you can get in, before the steam boiler's temp start affecting the brew boiler's t'stat.

Does that sum it up?

BTW, I use mine pretty much the same way you do as well. Most of the time, it sorta
works but whenever I'm doing more than my usual 2 shots in the morning (whether it's
changing coffee and it takes a couple/few shots to get it right or have friends over or
a few hot chocolates in between shots because kids have priority), then it gets a bit...
predictably unpredictible...

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sasquatchgeoff

#6: Post by sasquatchgeoff » Mar 16, 2011, 9:00 pm

expy,
I turn the steam boiler off and I can pull maybe 6 or 8 shots one right after the other consistently. I make one milk drink each for my wife and I, after that it is shots. So far so good. When I leave the steam boiler on for hours, I have serious control issues.

That pretty much sums it up... but wait! There's more!

Forgive my newbie status and potential post redundancy, but other behavior I am seeing is as the brew boiler sits longer while on (without the steam boiler being on) it gets hotter, to the tune of about 2 or 3 degrees c, which correct me if I am wrong, is a deviation in the opposite direction of the issues discussed at length (loss of heat) in other posts. Again, I flush until it stabilizes.

In other words, I have a machine whose heat is all over the map. I cannot pull decent shots at 84c nor 97c, and those are some of the temps I am seeing in the span of 4 hours.

Maybe I'll chat a bit with Stefano.

expy98

#7: Post by expy98 » Mar 16, 2011, 9:09 pm

Geoff, that's a bummer. Hope it gets sorted out for you.

User avatar
sasquatchgeoff

#8: Post by sasquatchgeoff » Apr 09, 2011, 2:35 pm

While I wait for a proven PID kit, I have decided to dial in the thermostat on my DB Jr with both boilers on. While this is excess wear and tear on the steam boiler, as well as wasted energy, I have found this solution to be a satisfactory temporary fix. There is only a degree or two variation in brew temp (91.5-93) and that is close enough for me.

With my grinder set-up and my method (yogurt cup funnel included) tweaked, I successfully pull spectacular shots consistently. Loving this machine.