Adding Thermometry to a La Pavoni Europiccola - Page 21

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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[creative nickname]
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#201: Post by [creative nickname] »

Matt, it is awesome to see another photo of your crazy modifications!

Maybe I'm missing something, but I would think that you should be able to get a declining profile without the dissipator, so long as you start the shots at a cooler group temperature.
LMWDP #435

mathof
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#202: Post by mathof replying to [creative nickname] »

I'll experiment with that idea and report back.

Matt

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mathof
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#203: Post by mathof »

The difference isn't night and day, but it's detectable in both numbers and taste. Without the cooling ring, and pulling the shots when the group is 1.5C cooler, the temperature starts at 93.8, rises to 94.5, then falls to 91.6 where I stopped the shot. With the cooling ring back on, and pulling 1.5C warmer than the previous shot, the temperature falls steadily from 93.9 till the end of the shot. This is not much difference, although the rate of change shows that the first shot stayed hotter longer in the first half of the pull. More importantly, the flavour was distinctly harsher and less palatable without the ring.

Given such matters as confirmation bias and the fact that I only pulled two shots to make the comparison, I wouldn't bet the shop on these findings. However, I'm tired of these tests for the moment and as I am happy with my current pulls, I invite others to see if they can get a downward brew temp profile with a pre-millennium LP. (They wouldn't need to make the cooling ring comparison.)

There is one other point that is worth noting. The temperature of the preinfusion varies with the temperature of the group and this may also bear on the taste. The boiler pressure I use is 0.8 bar.

Matt

Bigpikle
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#204: Post by Bigpikle »

Very interesting thread that has inspired me. I now have a digital thermometer and K-type thermocouple attached to the side of the group bell on my 1975 Pavoni, just at the ridge where the bell flares out to accommodate the PF.

My question is what temps people are using as the trigger for the shot? I've done 3 so far, with the best being the first at 102 deg C/216 F. That seemed high so I tried the next couple slightly lower with the last at 100 C/212 F but these lost the sweetness and werent quite as nice. This still seems high though?

Challenge is that after reaching the 'boil', bleeding the steam a little and pulling a warming flush through the group, the temp seems to settle around 102/103 C for the next 10 mins. The only was to cool it below 102 seems to be switching it off and waiting for it to cool and then pulling the shot, but that definitely results in less crema as well.

Any pointers would be appreciated. Thanks.

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drgary (original poster)
Team HB
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#205: Post by drgary (original poster) »

The outside group temperature runs higher than the temperature at the coffee cake. If you want to experiment with this, punch a hole in a filter basket, thread a thermocouple through it, load it with coffee and pull a shot measuring outside and inside temperatures. Your taste is already telling you, though, that this is what happens.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

Bigpikle
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#206: Post by Bigpikle »

thanks Gary - will just keep experimenting and perhaps get a spare double basket.

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russel
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#207: Post by russel »

So, after many months I finally got around to turning my sketch into some actual thermometer holding gaskets:





They are a lot better than my lab clamp, but unfortunately the thermometer on the LP that I actually use is busted. If anyone wants a pdf with outlines that can be printed, cut out, traced onto tap covered gasket material, and cut out with a mat knife, just PM me.
russel at anacidicandbitterbeverage dot com

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rpavlis
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#208: Post by rpavlis »

Infrared thermometers really do work remarkably well on brass surfaces that are coated with a polymer coat. (The polymer has high infrared emissivity.) They also work remarkably badly on bare metal surfaces. These devices typically have a red laser to see the location for which the temperature is being measured. The "real" brass and copper Europiccola that I have has an uncoated copper boiler, and the remainder of the machine has polymer coat. One can simply move the reading spot all over the group and tell what temperatures are present at different sites. This avoids having cumbersome wires every where and permits scanning temperatures at many points very rapidly.

The infrared emissivity of bare metal is very poor, so to read temperatures on chrome or gold plated machines requires sticking tape onto the spots where one wants to measure the temperature. With my 1999 Europiccola the best place to point the laser seems to be close to the bottom of the group, right at the end of the flared area.

These devices are now extremely inexpensive. They also are quite small and unobtrusive. There are no ugly wires!

jonr
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#209: Post by jonr »

Bigpikle wrote:My question is what temps people are using as the trigger for the shot? I've done 3 so far, with the best being the first at 102 deg C/216 F.
I start the sequence (ie, raising the lever, with descent about 15 seconds later) when the outside of the group head (side, narrow part) rises from cold to 76C. While I haven't checked this machine, I can tell with a high degree of certainty that I'm in the correct low 90s for coffee brew temp (similar to Matt's numbers). So I'm curious why the vastly different results.

With the boiler at ~117C and stable, pre-brew group head temps of over 100C, it's not clear to me where 93C water could possibly come from.

day
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#210: Post by day »

Just finished working on a La Pavoni (not sure what year it is, looks like the seller was dishonest when she said her sister got it in Italy during the early 80s, as there is no way this is from early 80s based on my research). Anyway, I I have really appreciated this particular thread. I would never have thought to break open a thermometer, but I had partly melted an old Man Law while roasting some beans, so I went for it. This thermometer is great for this purpose. The glue was on the top side, so a little goo gone and a dunk in hot water stripped it out. The temp probe on the end is coiled in a protective sheath and looks pretty solid. It is also mostly clear and very unobtrusive, and the shell is black, with the front side containing the battery so it is easy for switch outs even while mounted.

I decided to buy some O rings-2 or rings for the group and 1 o ring to put around my Pressure gauge adapter nut.

I superglued the plastic back of the thermometer to the small o ring so I could snap it on the adapter without actually mounting it. It worked great but hung a little low. I could have superglued a piece of o ring on to it on the bottom side, but didnt plan ahead, so I just slid my little metal prong from my MDF (I took it out when I made it stepless) and it works perfectly. Thermometer stays cool and it stays up right.

I then cut up an o ring and super glued to the larger o rings to make a kind of softer pocket, so that it wont crush the tip of the thermometer probe. Slid it in one, looped it, and then under the second to keep it pressed against the group. Really excellent data and shows the benefits of ice bathing the portafilter very clearly.

Here are some pictures of my set up:
Yes, i you per this on an iPhone