# Elizabeth - higher pressure with shot compared to blind basket?



## af22 (Jun 12, 2021)

Hello experts.

I am 300 cups in with my new Lelit Elizabeth (which replaced my 2009 Gaggia Classic). I am currently working through some channeling issues so I wanted to test what my OPV is set too. When I use the blind basket and pull a shot, the manometer shows 9 bars perfect. I can repeatedly pull shots into the blind basket and the manometer will never go over 9 bars. But, when I pull shots with coffee in a regular basket, the manometer will spike up to 10.5 bars for a couple seconds before dropping back down to 9 bars. I don't understand how it can spike to 10.5 bars when the blind basket never goes past 9 bars? I am using the steam preinfusion (5 seconds pump, 8 seconds total).


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## DavecUK (Aug 6, 2013)

Turn off the steam preinfusion, go to bloom phase or use not preinfusion, and I will bet it doesn't spike?


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## af22 (Jun 12, 2021)

Today I pulled 2 cups with no preinfusion (i left the steam boiler on), the pressure got up to 9.5 bars for a few seconds before dropping under 9 (this is lower than 10.5 bars with steam preinfusion). I still dont understand how it can go higher than 9 bars which is what the blind basket maxes out.


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## RobDGio (Jun 17, 2020)

I'm also having this issue, where I am often getting close to 11-12 bar of pressure when pulling a shot but only ever hit 9 bar with blind basket. Keen to hear what people think&#8230;.

I had wondered if I was grinding too fine and therefore getting high pressure (but also getting lots of channeling) but couldn't work out how this would be possible assuming the opv ensures 9 bar when using blind basket&#8230;.bit stumped


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## MediumRoastSteam (Jul 7, 2015)

Ok&#8230; so, let me try to understand this:

- machine is on and up to temp;
- button A is configure to have no pre-infusion what so ever. Settings read "OFF".
- lock the portafilter with a blind basket / blank disk;
- press button A;
- manometer registers 9 bar (let's call that X);

then, you do the same steps as above, but, instead of using a blind basket, you just brew coffee and the pressure goes over X by one bar or more (e.g: 9 bar with the blind portafilter, but 10 bar when brewing a coffee)

makes no sense.

Is there a chance you guys could video the entire procedure to see if we can spot anything?

thanks!


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## 27852 (Nov 8, 2020)

What sort of pump run time are you doing with the blind basket? Is this the back flush cycle? Is it with a bunch of puly foam or pure water?


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## DavecUK (Aug 6, 2013)

DavecUK said:


> Turn off the steam preinfusion, go to bloom phase or use not preinfusion, and I will bet it doesn't spike?


 I think what must be happening...because I don't quite have a production machine...almost. When steam preinfusion is taking place, a small amount of extra heat enters the brew boiler. Because the pump is not running, the pressure from the pump normally vents out the expansion valve. I think this way must be closed during the solenoid opening for steam preinfusion. Water expansion on heating then raises the pressure slightly. As soon as the pump comes on again I expect it pretty much instantly drops away?

I'm also guessing the coffee will be ground quite fine.

I wouldn't worry about it though...but you could try increasing the initial pump run time before steam preinfusion!


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## RobDGio (Jun 17, 2020)

MediumRoastSteam said:


> Ok&#8230; so, let me try to understand this:
> 
> - machine is on and up to temp;
> - button A is configure to have no pre-infusion what so ever. Settings read "OFF".
> ...


 I'll get a video done in the morning. But yes, as you describe, no preinfusion what so ever but getting a higher pressure with coffee which jumps up to about 11 bar and slowly drops to around 9 bar. Sometimes under. However with a blind basket, Hits and holds 9 bar. It's only started happening recently as was not an issue before. Initially I thought a dialling in issue (think you've replied to me on my other post) but now not so sure. As you say, doesn't seem to make sense


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## af22 (Jun 12, 2021)

Kjk said:


> What sort of pump run time are you doing with the blind basket? Is this the back flush cycle? Is it with a bunch of puly foam or pure water?


 I press Button1 (no preinfusion) with the blind basket and let it go for about 45 seconds. I've tried also with some water prefilled in the blind basket.


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## af22 (Jun 12, 2021)

DavecUK said:


> I think what must be happening...because I don't quite have a production machine...almost. When steam preinfusion is taking place, a small amount of extra heat enters the brew boiler. Because the pump is not running, the pressure from the pump normally vents out the expansion valve. I think this way must be closed during the solenoid opening for steam preinfusion. Water expansion on heating then raises the pressure slightly. As soon as the pump comes on again I expect it pretty much instantly drops away?
> 
> I'm also guessing the coffee will be ground quite fine.
> 
> I wouldn't worry about it though...but you could try increasing the initial pump run time before steam preinfusion!


 Dave, thank you for your theory and detailed explanation. I will continue to fiddle with the settings and keep an eye on it.

The reason why I posted this thread was because I'm having some channelling issues, and my puck doesn't always come out cleanly (sometimes parts of it is stuck in the basket, other times parts are stuck to the shower screen). I was wondering if that initial 10.5 bar of pressure might be the culprit. I am grinding with a Niche Zero to IMS Barista Pro Nanotech Basket and I also swapped to a IMS Shower Screen to see if it would help.


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## 27852 (Nov 8, 2020)

Channelling is most likely attributable to puck prep / distribution rather than a machine problem so the OPV setting may be a red herring.

What is your puck prep workflow? How are you sure that it is channelling? Do the shots taste ok?

Preinfusion really helps to mitigate problems with the puck. Try 4s initial pump run with 12s of total PI using steam, if you're using a bottomless portafilter you should see coffee bead and cover the bottom of the basket the end of PI, maybe a few drips. If it happens too fast with flow into the cup during PI then you may are likely grinding too coarse, if you see nothing come through, too fine. If it is uneven then look at distribution before tamping.


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## af22 (Jun 12, 2021)

This morning I tried to make a video. To my surprise, the first pull with the blind basket hit 10.5 bars! Then the second pull with the blind basket was back to 9 bars. This is exactly as described in the other thread: https://coffeeforums.co.uk/topic/58976-lelit-elizabeth-opv-issue/ by user *strafe. *In my haste to attempt to film it, my routine was slightly different where normally I press button1&2 to let some water run for the preprogrammed 6 seconds. Today, I forgot to release some water - the machine was left preheating for over an hour.

Kjk, to answer your question. I have tasty shots without preinfusion, as well as more consistent pucks without preinfusion (maybe because I can grind courser?). I'm still struggling getting my shots to be as consistent and tasty with preinfusion (maybe because I have to grind finer?).


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## 27852 (Nov 8, 2020)

af22 said:


> This morning I tried to make a video. To my surprise, the first pull with the blind basket hit 10.5 bars! Then the second pull with the blind basket was back to 9 bars. This is exactly as described in the other thread: https://coffeeforums.co.uk/topic/58976-lelit-elizabeth-opv-issue/ by user *strafe. *In my haste to attempt to film it, my routine was slightly different where normally I press button1&2 to let some water run for the preprogrammed 6 seconds. Today, I forgot to release some water - the machine was left preheating for over an hour.
> 
> Kjk, to answer your question. I have tasty shots without preinfusion, as well as more consistent pucks without preinfusion (maybe because I can grind courser?). I'm still struggling getting my shots to be as consistent and tasty with preinfusion (maybe because I have to grind finer?).


 Understood - the PI does allow you to grind finer and is a mitigant for channeling. If you're getting better results without then I'd stick with that rather than have to dial in again with a new style of shot.

My button 1 is programmed for PI and there is nothing on my button 2 in case I fancy a straight up or allonge style shot. I never pull bloom shots because I don't see the point.


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