Monitoring Brew Temperature - E61 & Silvia - Page 5

[stevendouglas]

Bob,

I wish I would have asked you sooner. I ordered the K-type thermocouple but with the teflon coated insulation. It appears that the T-type has a smaller (yet completely adequate for anything related to espresso) temperature range than the K-type, but I didn't see any other differences. Are there any differences in response time or accuracy (the accuracy looked to be the same ~ 0.4% for both).

I ordered both the SC-TT-K-36-36 and the 30-gage, thinking exactly the same thing you did - the 36 gage might too fragile. I'll let you know how that turns out. I'll definitely try monitoring group temperature.

The thermocouples arrive today, so I'll let you know about the group and brew water temperature.

Thanks again for all of the information. I think that real-time monitoring of the brew (and group) is going to dramatically improve what's already a great machine. AND, it's likely to remove any GS-3 envy that I might otherwise have had!

Steve

[Bob Barraza]

Steve,

I'm afraid that you are asking questions beyond my level of knowledge. I would guess that the accuracy of either would be more than adequate for the intended use. The smaller diameter should in theory give a faster response time. Presumably the teflon coating will make it compatible with the hot water environment.

Another surprise for me is how little adjustments I need to make from day-to-day on my grinders (Mazzer Mini and Mazzer SJ) now that I am using the WDT and temperature monitoring. Several days go by before I make the most minute adjustment to account for aging, yet delicious shots just keep falling out. Trust me, all shots are carefully timed, volume checked, as well as bottomless portafilter monitored via pre-set mirror. This is possible due to the stability and reproducibility of the A3, but only apparent after I struggle to minimize the operator variability. The longer I have the A3, the happier I am with it. How often does that happen!

[stevendouglas]

First, the teflon insulated thermocouples are MUCH better (no issue with water or abrasion) than the glassbraid insulated thermocouples. Moreover, the 36-gage teflon thermocouple (SC-TT-K-36-36) appears more than durable.

I connected one as shown in the post above inside the group to measure brew temperature as it's entering the group (Brew Temp), and wedged another between the group and the three-way valve (Group Temp).

The readings (These are just my first three or four pulls. I haven't had a chance to really examine these results nor download readings, which I'll do and post):

1. Brew temp: After several hours of idle time, the water temperature starts at around 225F, hangs there for several seconds and then drops fairly rapidly. This surprised me as I expected it should start at around 212, hang there until you flush the brew water from the HX, and then drop. I'd be interested in your experience with the temps.

2. Group Temp: This tracks fairly well; however, my temperatures were much lower than yours. The Group Temps I observed were in the 190-195F range, rather than 200F that you observed. The Group Temp never reached 200F on mine). This is most likely due to the difference in where I placed the thermocouple.

I plan to put a thermocouple in the group head below the dispersion screen as you show above and see what temperatures I monitor. Play with the placement of the thermocouple in the group head above the dispersion screen. I'll graph these and see what comes out.

Thanks for your help.

[cafeIKE]

Be aware of leakage down the wire if using thermocouples with multi-piece connectors.

It is possible for fluid to be forced down the sheath and / or wire inside the insulation and leak into the meter.

This is less of an issue when using molded plugs.

[Bob Barraza]

Steve,

The maximum brew temperature will depend on the p-stat setting for the boiler. I have mine turned down so that it averages slightly below 1.0 ATM. At idle, without starting the pump, the meter will read about 202 deg. for the brew water and about 201 for the group. However, to conserve energy, I keep a dish towel wrapped around the group and portafilter to act as insulation. Without the towel, yes, the group temp quickly drops to 190 to 195.

My process is to begin with a conditioning flush. The brew water will peak around 215-219 (for my boiler setting) and then quickly drop. I stop around 5 degrees above my target brew temp, or, about 206.

Next I quickly dose and tamp (using WDT). I do a final rinse to my target temp, around 201, stop the pump, start my timer. I use a 10 second rebound time which is enough to position cups and lock the portafilter and start the pump. The timer continues so that I can time the shot as well.

If you want to raise the group temp, flush until the brew water temp just begins to drop (about 215 in my case). After a few seconds, you will see the group temp rise a bit. With a series of short hot flushes you can raise the group temp. The group cools quickly. Having the portafilter loosely locked in place helps, and the dish towel at idle helps even more.

I didn't use the TC attached to the bottom of the dispersion screen very long, but it quickly damaged the TC cable. The 36 gauge wire might require less torque to get a seal, but the 30 gauge might be more robust.

Good luck.

[Pick335]

For the first week, I pretty much ignored the adapter readout while flushing. That's how I arrived at 206F as the "right" temperature to stop flushing. When I did peek at the numbers, I was usually within 0.5F if it was one of the later shots and the pace was not faster than one every three minutes (i.e., leisurely weekend mode). For the first shot, the adapter readout confirmed what I had long suspected - the temperature spikes higher than normal - and had already compensated by subtracting a few seconds from the rebound time.

So yes, I was able to improve on brew temperature reproducibility, especially for the situations where the water dance method is tricky (e.g., a shot pulled between 1m30-2m30 after the last). Bob Yellin's simple rule of "flush two ounces if it's less than three minutes" works reasonably well for that situation, but the adapter enabled me to improve on it.

In summary, those who worry about the complexity of HX temperature management have a solution that a half-blind one-armed barista suffering from a mild case of AADD could not screw up.

Hello Dan...I almost resemble that remark, actually, my Famosa has a HX and if I could impose on you to expound on the water dance procedure I would appreciate it. I look forward to the adapter once I get truly proficient with this new machine. Consistent shots are alluding me but that is to be expected at present.

Thanks,

[cafeIKE]

This is on the How To Page
How I Stopped Worrying and Learned to Love HXs

[mhoy]

... I took a chance and ordered 30 gauge thermocouples that I intended to lay across the gasket and guided it down one of the four holes in the lower half of the group (the center hole is used to screw in the shower head and screen)...

Would you happen to remember the part number or where you ordered this from? I think I'd like to try this with my Elektra rebuild.

[EDIT:] OK, I've now read more of the thread and found SC-TT-K-36-36 which appears to be a Omega part number. Anyone order the 5 pack and want to sell off a couple? [/EDIT]
Mark