Eric - Not so fast my friend! My giotto is set to 1.1, and it also runs around 220'. It was scaled up when I got her, but the temp never got hot enough to even sputter when flushing (I had an old thread somewhere about that long ago). I think this is normal behavior.

Kenja - what is the temperature DURING the shot? That's the key! Report back with results. That will give you a repeatable temp of the water brew temp (not necessarily absolute, but accurate). Since my gh also sits at 220, I think the thermometer is pretty correct anyways).

It sounds like you are on the right track anyways, check out Jim's guide to espresso to determine what flavors you don't like about your coffee and it will guide you to try hotter or cooler.


Geoff

I was out of town for the weekend... Here are my updates.

I ran some profiles on my machine to emulate what Eric did. The temperature started at 223 deg F. I had to flush for a full 60 seconds to get the temperature down to 185. The flush was about 12oz.




A few words of explanation are required. First, these were read and transcribed from the GH thermometer attachment. Second, the shot profile was taken after a different flush than the one in the chart provided above. The "shot profile" run's flush was started at 210.5 deg F since I didn't give it enough time to fully recharge up to 223. Interestingly, that caused the low point of the recovery curve to drop to 192 versus 194 on the full temp run shown above. The recharge to 198 took longer as a result. I didn't measure the exact time... Once I hit 198, I pulled a real shot to measure the Shot Profile. It seems to show a higher shot temp by between 3-5 degrees versus Eric's measurements. The net temperature drop during the shot was pretty consistent with Eric's at about 11 degrees over 30 seconds.

I didn't measure the exact time for the machine to go from cold to 223 deg F, but I think it was in the neighborhood of an hour.

Do I need to adapt my flushing routine depending on what GH temp I start the flush from? It appears that the recovery changes depending on the starting point. Or does taking longer to recover not affect the resulting shot temp?

It looks like the flushing routine on my Giotto takes about twice as long as with Eric's machine. My machine seems to put out about 6 oz every 30 seconds based on measurements I've taken. Is that normal or is the pump not working right?

So based on these results, do I start the shot at 194-195? I guess I just need to keep running tests until I get a shot profile that is in the ballpark.

A couple questions about previous posts... Eric's thermofilter measurements show a ~5 degree degradation over the duration of a shot. Is that normal? I keep hearing that the goal is to keep it within a degree or so.

I still think you're flushing too much. Just try flushing to 205 or 201 and then wait a bit and pull your shot. There is no need to cool to 185. I think that's why your shot is unstable and losing temp.
Geoff

I still say that if you're trying to avoid running the vibe pump, on the giotto's unrestricted hx, for too long, I would stick with the shorter flush, and when you flush this way, the temp is much more stable than the drop in Kenja's chart above, ie, less than a 1' drop is typical.

Geoff

I turned the boiler down to 1 bar and that seems to have dropped the temp down to ~210-212.

I ran several shot profiles and the results are shown below. Unless otherwise specified the data was collected at 1 bar.




The new profiles look pretty similar in terms of slope although the big flush is slightly better. I missed the 0 sec data point on the 202 run as you can see. What's interesting is that I ran the 205 + 10Sec flush at 207 and got exactly the same result as the 205 run. I'm not sure why. I'll play around with it some more, but for right now it looks like a 185 flush with a 195 start is the ticket to get me going while I figure out the "flush and wait a little".

Thanks,
Kenja

kenja wrote:I'll play around with it some more, but for right now it looks like a 185 flush with a 195 start is the ticket to get me going while I figure out the "flush and wait a little".

If you're measuring with Eric's thermometer adapter, I'd go with the 205 + 10 seconds line (violet). The first 10 seconds of the thermocouple adapter is higher than the actual brewhead temperature measured with a thermofilter. The two readings merge about midway through the extraction. The chart below is using a type T thermocouple, which reacts faster than your thermometer, so you may have to subtract a degree or two from your data points for comparison purposes.


From Monitoring Brew Temperature - E61 & Silvia

erics wrote:To change the subject a little - there's a lot of Vibiemme's being sold because of the thorough review process that's going on. Hopefully all of these Vibiemme's have thermosyphon orifices installed. If it's right enough for the V, it should be equally right for the G. This would dramatically reduce any cooling flush requirements but the recovery process would be slowed a little.

A few months a back, I was experimenting with flow restrictors and got some from Espresso Care