I'm surprised this topic doesn't pop up more often than it does - turning the e61 lever to the halfway point just before the pump engages, to soak the puck before turning the lever the rest of the way to engage the pump.
I think the common response when this has popped up before here is that the e61 works fine as is. But like many I can't help myself from trying different techniques.
So lately I've been trying the halfway lever method for 5-10 seconds before engaging the pump. The results are interesting. It certainly hasn't affected the quality of the coffee, and the consistency of flow through my naked PF is definitely very good, perhaps better than before.
To see if there was much water actually entering the puck I weighed the PF after tamping and then after the wetting and it seems to add 5-10 g of water to the puck, very roughly 1 g of water per second, so it certainly saturates the puck to an extent. This is on a giotto with a tank and an 18g dose.
But has it improved taste? Well I'm not sure I can pick up a perceptible improvement that isn't psychosomatic. But I've only tried it with one bean so far (Colombian) and I'd imagine different beans would react very differently.
I'm curious if anybody uses this method regularly, or is it just one of those things we all try once?
Funny, I was just rolling the pre-infusion thing around in my head again this morning. I did a bit of experimenting when I first got my E61 (running from tank) and came to your conclusion - could not definitively decide if it had a positive effect. Didn't seem to have any negative effects though. In the end I decided to leave it out and focus on all the other things that have a definite effect and come back to it some time, perhaps if I ever plumb the thing in.
Enjoyed your post - so many things in this game are subtle and I'm often surprised how people try something once or twice and then report how amazing it is. I think your approach is great - nothing wrong with experimenting, even with things that have been done before. You never know when you might stumble across something good.
Last edited by Pete39; 8th December 2013 at 11:41 AM.
Reason: typo - left out the word "not".
I understand what your getting at, however for water to flow through an E61 group head the pump needs to be running, this is certainly the case with my Bezzera machine, I can move the lever to the half way position and not a drop of water exits the group head.
Originally Posted by Yelta
Some machines will release some water from the HX without activating the pump. The biggest determinant is how the lever microswitch is set and how far the lever can be raised beyond midpoint before activating the pump. If the microswitch is a little further back, the behaviour Jonathon has described will almost always occur. Whether it's of any benefit remains debatable as e-61 groups preinfuse anyway.
I just tried this on my ECM. Interesting in that it's helped me understand a little more about my machine. I had previously, and erroneously thought that the behaviour you describe would only happen on a plumbed machine with line pressure causing flow prior to the pump being activated. My tank machine does indeed show the behaviour you describe but water doesn't flow at the middle detent (as Talk Coffee describes above). It's somewhere between the middle detent and the detent which causes pump activation. I can only assume that at that point the valve opens and a small reservoir of water can fall through the group head using gravity alone. Having tried it once and seen what happens I'm unlikely to keep doing this "pre-infusion pre-infusion" for two reasons:
1. The reservoir above the group head must be pretty small. I did a flush immediately post the extraction and got a heap of superheated water sizzle. To me this means that the water that moved through the group (post pre-infusion pre-infusion) straight from the heat exchanger did not have time to equilibrate thermally with the group head. I think that there is a strong likelihood that you'd get brew water that was too hot using this method (at least in the first part of the pump activated extraction); and
2. From other people's experience and reading a few posts on the LM GS3 Paddle, generally people have found that plumbed in line pressure pre-infusion has been helpful for forgiveness but have not found that pre-infusion for the tank GS3 (driven by pressure from the steam boiler I'm led to believe) was helpful.
Really interesting topic to bring up. Thanks.
Thanks for the explanation Chris, so, for water to flow without the pump running there must be pressure in the system or it is simply gravity fed, if gravity, then this would be dependent on the water level in the tank, i.e. low water = no flow.
Originally Posted by Talk_Coffee
Or am I barking up the wrong tree?
My first machines were vibe pumps which have a 'natural' ramp up to pressure.
The pre-infusion time was about 9 seconds..........from activation to pour.
I now have a rotary pump. It comes up to pressure and begins the pour in 5 cedonds.
I have been habitually extending the pre-infusion dwell time so the pour statrs in 9 seconds.
The coffee is great, like I said it's habitual................possibly not necessary but my palate tells me it is
By the way, Yelta, it's not relevant to tank level, so I presume static line pressure.
I usually keep my tank quite full, so I assume (perhaps wrongly?) that it's simple gravity in operation - keep the tank level higher than the group and water will flow.
Originally Posted by chokkidog
If it's not gravity, what would cause the water to flow when the pump isn't running, in a tank system?
Water in the boiler section of the HX will be at boiler temperature..IE above boiling point.
Originally Posted by Jonathon
That could effectively pressurize the sealed HX loop, and force water out when the brew valve is opened.
This could explain a brief flow , but not a continuous flow.
Yesterday I had my Giotto turned on but didnt notice I left the handle half up... Once it started to boil, I normally can hear the pressure valve starts to build up before it stops...
Anyway, it started to boil and I started to hear a knocking sound that came out from the group head with water starting to drip out.
So I would assume it is related to pressure building up that cause the water come out.
Mine is a plumbed in Giotto and it releases a trickle of water with the lever in the 1/2 way position an agree with blend52's explanation.
I've been doing a 3 second pre infusion consistently for a few months now and can't really say for sure if it effects the flavour but loading up the puck with some water does seem to help getting a nice even rat's tail pour with a naked portafilter.
remember, as TC said above , E61 groups have a built in automatic low pressure pre-infusion function even when the pump starts.
Originally Posted by fg1972
Also, i just rechecked my tank feed E61 with the lever raised to mid point.
Cold = no flow
Hot = slow flow for 5-10 secs..but then just steam ! ( and it took 5 secs or so for the pump to refil the HX after the lever was raised fully )
So it would appear that it is a HX temperature effect.
Been away for a couple of days, so I turned my machine on before the computer.......... priorities, right? ;-D
The machine was already warm by the time I read the above so I was only able to check the flow once Alex was hot.
Engaging the cam to the halfway point allowed low pressure water flow with no pump activation.
Still flowing @ 40 seconds, so I stopped and opted for a coffee. ;-D
Not sure how long it will go for, or what determines the total possible flow sans pump, probably something to do
with the brew boiler size.
Difference between Double Boilers and Heat Exchangers?
Last edited by chokkidog; 9th December 2013 at 11:16 AM.
Reason: a couple more thoughts
Is that machine on mains supply ?
Originally Posted by chokkidog
What volume does 40secs represent ?
What temp is the brew boiler ? ... if its hot enough, maybe its vapour pressure will push the brew water out ?
You're in luck! ;-D.................. Next time say please! .... Please. :-D
Originally Posted by blend52
1. I'm guessing you mean water so that's a no; it's tanked.
2. 35 seconds yields 190 ml. Still flowing but the latté glass is only 207 ml.
3. PID set to 93°C.
Interestingly tho', when bleeding water from the brew tank via the group head the brew boiler temp increases;
@ 35 seconds it was 100°C.
Immediately afterwards I engaged the pump, the temp stabilised instantly and then I pulled a shot.
The brew temp did not increase with 5 seconds of 'on hold' pre-infusion. Nor 10 minutes later, when I pulled another one.
.. Please. :-D....Ok,
you should be able to see if the 190 + ml has drained from the tank or if its just the boiler emptying ?
Do you know the capacity of the brew boiler ?
Or you could just repeat the test when the machine cools down ! ...............Please !
My Alex has the 0.8 lt brew boiler.
At a guess, with the brew boiler temp increasing, I'd say that it's just water from the boiler.
But I'll check.
Tonight, when it's cooled down. :-D
I checked my tanked Giotto this morning when cold, not a drop came out (tank was full).
So I think we can safely say it's a heat/pressure effect rather than gravity that pushes out water without the pump, at least for a tanked HX Giotto.
Also, I seem to get more out when the machine has been on for a few hours, compared to when it's been on for just 45 minutes.