brew temperature problem, pre-infusion temperature is way high..

Beginner and pro baristas share tips and tricks.
jeffg

Postby jeffg » Jan 06, 2008, 11:45 pm

I want to pull my shots around 198-199 (assuming this is 202-203 on my e61 group head thermometer that I installed). I seem to be able to get the shot temp steady however the pre-infusion temp is like 208-209 then quickly drops to 202-203 target range. If I work to bring the pre-infusion to 202-203 range it blows the secondary shot temp as it then goes down to 190's. Do I just ignore pre-infusion temp? I have also tried flushing to 187 and trying to pull on the rebound but infusion temp is still way up and still my target temp is not steady until about 6 seconds into the pull. I also tried lowering boiler to 1.1ish (domobar super) Thanks for any advice..

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HB
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Postby HB » Jan 06, 2008, 11:58 pm

jeffg wrote:Do I just ignore pre-infusion temp? I have also tried flushing to 187 and trying to pull on the rebound but infusion temp is still way up and still my target temp is not steady until about 6 seconds into the pull.


Eric's thermocouple/thermometer adapter isn't reading the actual brew temperature. Depending on the particulars of the espresso machine and the flush technique you employ, the adapter reading and the actual brew temperature won't merge until 10-15 seconds into the extraction. From Monitoring Brew Temperature:

Image
Temperature within the valve chamber exit (blue) versus thermofilter (red)

The chart above is for La Valentina. The Vibiemme Domobar Super will not spike as high shot-to-shot, but will still have a distinct "hump" in the initial third of the extraction.
Dan Kehn

jeffg

Postby jeffg » Jan 07, 2008, 12:06 am

so if i flush to say 205, then backflush and 3secs into backflush i hit 203 i could then pull the shot and then be somewhat ok? thanks

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HB
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Postby HB » Jan 07, 2008, 12:32 am

Jon's blind flush technique is another story (see Need hints on using E61 thermocouple adapter). I found it worked quite well on the Vibiemme, i.e., flush unimpeded to the ballpark reading, add the blind basket, raise the lever to pressurize, check the temperature. Repeat until you're within a couple degrees of the desired brew temperature. The actual delta reading will vary depending on the depth of the probe; I only worry about repeatability and don't think about the precise numbers.

That said, this technique approaches "brew temperature precision for sport" territory. Dave's writeup and simple flushing instructions will get within 1.5F every time and the blind flush technique will halve that.
Dan Kehn

jeffg

Postby jeffg » Jan 08, 2008, 6:42 pm

I'm still wrestling with brew temp. I have everything else figured out except temp. Is there anyone with a domobar super + grouphead thermometer that could tell me exactly what you do? for example: -let machine heat for 1hr, flush to 210 and wait 30seconds, blind flush to 2xx wait 15seconds, pull shot etc. Today i pulled one shot at 193 and another at 206 no matter what I do that appears to have the temp in range 10secs into the shot it's one extreme or the other. If someone with my similar setup has this nailed down your exact routine would be a real life saver! PS include your boiler setting too please. thanks

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HB
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Postby HB » Jan 08, 2008, 7:21 pm

jeffg wrote:Today i pulled one shot at 193 and another at 206 no matter what I do that appears to have the temp in range 10secs into the shot it's one extreme or the other. If someone with my similar setup has this nailed down your exact routine would be a real life saver!


Does the espresso's taste indicate a large swing too (bitter to sour)? Dave's instructions in Pulling shots by the numbers are simple. Are they not working for you (thermometer readings aside)?
Dan Kehn

jeffg

Postby jeffg » Jan 08, 2008, 7:39 pm

The flush amount varies by boiler pressure and desired temperature. Generally speaking it's a few ounces if the machine has been idle for awhile



My boiler is around 1.1 and if i only flushed a few oz i'd be pulling shots at around 210 according to my thermometer. Maybe cannonfodder can chime in as i think he has or does use the domobar super with thermometer. Would love to know his routine.

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erics

Postby erics » Jan 08, 2008, 7:49 pm

The videos and the data presented in the Vibiemme review are pretty darn good:

/forum...r-super-t4019.html

An important consideration would be what your thermometer reads after a long term idle (1 hour or more) ?

As Dave noted in the linked review above, his boiler pressure gage was 1.10 bar (max reading) and his grouphead temperature was 200-201 F - this relatively cool group as a result of the thermosyphon restrictor installed (by the dealer) in the Vibiemme under review.

There are numerous ways in which to produce a good shot on different espresso machines and, as I demonstrated here, one can produce essentially the same temperature profile using different methods.

/forum...adapter-t5125.html

A lot also depends on the duty cycle YOU WANT to impose on the machine, e.g., making one cappy every 20-25 minutes would be considerably different than 3 or 4 shots in a 5 minute time span.
Skål,

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

jeffg

Postby jeffg » Jan 08, 2008, 8:09 pm

After leaving the machine on for 1hr my thermometer reads 213 is that a problem? I'll check the links thanks

jeffg

Postby jeffg » Jan 08, 2008, 8:24 pm

it seems that my machine might not have a thermosyphon installed. How dire are the implications of this? I have contacted the roaster where I bought the machine for their thoughts on the matter including some references listed here..