Setting VBM DD Brew Boiler Offset Temperature

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dgkula

#1: Post by dgkula »

Hi Everyone,

I recently ordered erics' thermometer to dial in my brew boiler offset. I installed it this morning and made a shot. The video is a bit all over the place because I am still dialing in a new bag of beans so I may reshoot and stay focused on the PID temp and the erics temp.

The PID temp for this pull is set at 198F and is reading that temp when I start the pull. The erics temp rises to 196F and dips to 193F during the pull and rebounds to 195F at the end of the pull. I think the average is about 194.5F.

I have seen other posts with graphs (here is an example: Using Eric's Grouphead Thermometer) that shows on a VBM E61 group the scace or puck water temp is about 4 - 5F less than shown on the erics thermometer. So in my case, does that mean the water at the puck is about 194.5F - 4.5F or 190F? So to get my target of 198F I should increase the brew boiler offset from 19F (default) to 27F?
Thanks!
David

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cafeIKE
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#2: Post by cafeIKE »

What year DD?

My orig '08 has no offset capability and I only use Eric's thermometer when adjusting a dial in. I replaced the original battery in 2019. If I feel a coffee needs a temperature adjustment, I just bump or drop it. Same as I did before Eric designed the e61 thermometer & adapter. IMO, one can become obsessed with the numbers. The display is a blue light that let's me know the machine is on.

The PID display is always going to be 'sort of' due to thermistor lag, PID update speed and position in the boiler relative to the water outlets. Eric's thermometer is a fair distance from the puck and also suffers from thermistor lag.

I have a Scace... somewhere :oops:

dgkula (original poster)

#3: Post by dgkula (original poster) »

I think it is a 2012 machine (definitely 2011+ based on diagrams on espressocare.com).

I guess if I'm pulling a shot 8F less than recommended by the roaster (in this case Dragonfly Crema Dolce) it is good to know to try and get closer to the target taste profile.

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Jeff
Team HB

#4: Post by Jeff »

At least in my experience, roasters' "recipes" aren't worth much past cooler/normal/hotter and shorter/normal/longer. Your grinder, water, and gear isn't what they have in their lab or at their commercial customers' shops. Some use the same across all their "espresso" selections.

Offsets between EricS and brew temperature will probably be very different between an HX and a DB. With an HX there is often hotter or cooler water coming in that gets moderated by the group head.

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cafeIKE
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#5: Post by cafeIKE »

The brew temperature profile as read w Eric's adapter is very close on the Vibiemme DB & HX machines. In both cases, for the later 2011 model DB, cold water is injected to the middle of the HX or brew boiler. The group is heated by thermosyphon, so the water cct is essentially the same. The temperature profiles start to diverge when multiple back to back shots are made, especially if steaming w the HX.

dgkula (original poster)

#6: Post by dgkula (original poster) »

This thread shows a graph for a VBM DD - looks like the erics thermometer temp is about 6F above the puck water temp:

Brew temperature offset for Erics thermometer