Source
r/espresso•
ChemEng

La Pavoni Lever Question

I pull 2x espresso every morning and evening. Same grinds and doses (15.7g). Fresh beans. Machine on ~30-60min to warm up. Portafilter warmed with pull from machine. ~10sec preinfusion.

Observation: On the first shot, there is a calm, fluid sound in the brewhead. But on the second shot, lifting the lever creates a noisy, gassy sound in the brewhead. The temperature between pulls appear roughly the same, per OE temp strips. The second shot always has increased pull resistance over the first.

The second shots are always better than the first. Always...

Can someone help me understand what's going on? Is there anything I can do to increase my first shot quality?

Posted Mar 6, 2017, 3:18 PM UTC

617
TheBistromath•

Europiccola or Pro version ?

30-60min seems to be long for the for the warm up. Mine (a Pro) is heated is less than 15 min. More than that the brewhead and is very hot (which you don't want).

Having a better second shot is something I hear often, but can't really comment since I only pull one...

Are you venting the "false pressure" (opening the steam wand for a few sec) before your first shot ? Having air in the machine will mess with the real pressure since it gives a higher pressure at the same temperature compared to steam alone. This might be what you are experiencing since the second shot will have a lower percentage of air in the empty part of the boiler and thus have a higher pressure coming in the brewhead.

I might've also said that there could be air in the tube going in the brewhead, but since you're pulling water before your first shot it shouldn't be an issue.

2
ChemEngOP•
  1. Millennium pro version. Overheating should be much less an issue for this model, I think.
  2. It reaches temp faster than 30 mins. I just typically don't pull shots until then.
  3. What brewhead temp do you pull shots at?
  4. I lift the lever to heat the portafilter and demitasse, not the steam wand. I'll try that out tonight.
1
TheBistromath•

  1. Millennium helps a bit, but I think it's overheating less when pulling shot

  2. 30 min seems reasonable, 60 seemed very long

  3. I don't have a temperature strip so I'm not sure, but I can touch it without burning myself

1
rantpaht•

Get the temperature strips from Orphan Espresso. For the second shot run the portafilter under cold water and lock it in to the group head, and leave it for 30 seconds and then repeat once. Then grind/tamp/pull shot and see if its better. This to me sounds like a temp management issue. Other considerations, I think that some lighter roasts might be much more sensitive to higher temperatures, what roaster/coffee?

2
ChemEngOP•

For the second shot run the portafilter under cold water and lock it in to the group head, and leave it for 30 seconds and then repeat once.

I tried this recommendation this morning. It did not change the differences between first and second shots.

1
rantpaht•

Either way you should get these: http://www.orphanespresso.com/Group-Temperature-Strip-Thermometer-High-Range-and-Low_p_2133.html

What have you done for maintenance?

1
ChemEngOP•
  1. I have them already installed. They show the same temperature for the first and second pulls. How do you use them?
  2. I got the machine new in August. I've run one Cafiza cleaning cycle through it. Nothing else.
1
hugochurch•

Is the increased resistance you refer to in your second shot all the way through the pull or is it that it engages more solidly and quickly at the top of the pull? If it's the latter, you likely have air trapped in the grouphead during the first shot. I recommend modifying your procedure as follows.

Before you warm the portafilter and grouphead by pulling water through them, lift the lever about 3/4 of the way up (before the point at which water is released from the boiler into the grouphead chamber) to release steam from the grouphead. Repeat this a few times. Now continue with your routine as normal.

This should result in your first pull being less spongy and being much more similar to your second.

2
ChemEngOP•

Before you warm the portafilter and grouphead by pulling water through them, lift the lever about 3/4 of the way up (before the point at which water is released from the boiler into the grouphead chamber) to release steam from the grouphead. Repeat this a few times. Now continue with your routine as normal.

Interesting thought. I'll give it a try tomorrow.

My suspicion is that the grouphead draws enough heat from the machine to condense the water/steam. Hence the fluid sound. But after the first shot the grouphead is already warmed, so the water/steam balance is preserved.

If that's the case, maybe I should pull a few shots of the initial water through the grouphead to clear that out? Maybe 1 shot isn't enough.

1
CommunistWitchDr•

Another point, do you flush your grinder, or have one with absolutely no retention? If not, the second shot could be better since it doesn't have half a gram of stale coffee mixed in, and the difference in sound might just be a red herring for the taste difference.

You could try measuring the resulting espresso temperature too, to see if it's any different. It won't tell you the group temperature of course, but if the second one is warmer it might mean that the inners of the group are warmer for shot two.

2
ChemEngOP•
  1. I use a Lido 3 hand grinder. (Light retention.) My work flow preps 2 portafilters worth of coffee at the same time. The second shot still tastes better than the first, even if it was prepped first.
  2. I didn't think about measure shot temperature. I've got a food thermometer that should work. (Also curious now how closely the group thermometer strips track actual temps.)
1
ChemEngOP•

I measured temp at the grouphead at 4 points today: after 30min warm-up, after portafilter warmup, after first shot, and after second shot. Here are the results: 150, 159, 163, 170.

But the interesting thing is that the temperature strips read the same ranges for the each reading after the first! The temp strips said 170. My thermometer said 150. That's a huge difference!

Also, I was surprised to see the temp strips not be as responsive to the change in temps that the thermometer showed.

Just have to figure out what to do with this. I'm starting to think I should get rid of those strips.

1
rantpaht•

Hi, I think you should keep the strips. The strips definitely aren't perfect, but they do work as guidelines to help you target a temp that you know results in a great shot. Alternatively, I think the temp study done on the cremina, does suggest that the barista can become pretty tuned to timing between shots, so that temp management can be done without the strips.

I also think you should post this question on home-barista if you haven't already.

It could be simply that the first shot seasons the machine for its day of work, and that the first shot results in temp consistency throughout the group head, maybe it just doesn't happen until that amount of water flows through the machine.

I have been told by professional baristas that they tune there machines every day, by pulling shots and tuning the grinder until they get the taste they want. Its a lot for us at home to pull five shots every morning to get it "perfect", but maybe thats the issue.

I'm curious do you the "Fellini move"?

Let me know what you think?

2
ChemEngOP•

I'm still not sure. This answers the question about why it sounds differently in the grouphead after each shot: the temperature increases (despite temp strips showing otherwise).

What I want to try to do now is get the grouphead to the temperature that I normally see after the second shot on my first shot. And see if that impacts the shot quality.

Right now I'm collecting temperature data at those 4 points to see if there's a trend. (I'm also curious if length of time the machine is turned on impacts grouphead temps.)

1
rantpaht•

I have a cremina, I'm assuming that you can cycle water through the La Pavoni Group head in the same way: Lift the lever up to the point just before water comes out and then down again, do this until the temp in the group head rises. Do you know about this way of controlling the temp? It might interesting for you to read this: http://10000shots.com/post/12435115597/olympia-cremina-temperature-study-part-1

2