Teme Senior Member Joined: 7 Jan 2005 Posts: 1,221 Location: Finland Expertise: I love coffee
Espresso: Londinium I Grinder: Mahlkönig K30 Vario
Posted Fri Jul 15, 2005, 7:47am Subject: Re: Please help me with my lever
I do not hold my lever in the middle position, i.e. I just "throw" it all the way up. The pump takes time to build up pressure and the pre-infusion chamber of the E61 do take care of the pre-infusion part.
Also, and others please correct me if I am wrong, the middle position of the E61 was intended for the true commercial E61 machines with rotary pumps (i.e. instant pressure, no delay) but have no use in a home setting. So how about the home machines with rotaries? I think the middle position is still redundant - but this is not knowledge , just a guess ;-)
Posted Fri Jul 15, 2005, 1:44pm Subject: Re: Please help me with my lever
For reservoir / vibe pump type machines, some water will dribble out when you raise the lever halfway since the HX is under pressure, but that's all. If you had constant line pressure and no solenoid cutoffs (*), water would flow through the HX under mains line pressure, providing a gentle preinfusion. Although I have no personal experience with it, I understand the Synesso has this capability (i.e., manual preinfusion under line pressure or an automatic preinfusion cycle).
Note: It takes quite a few readings to absorb, but the E61 patent description and diagram (below) make it clear what's going on in the "halfway" position (if I read the labels right, the short answer is "water can pass from chamber 3 to chamber 14").
(*) My plumbed-in machine includes a water inlet solenoid to prevent backflow in the event of a mains pressure failure, so active line pressure is not present at the group unless the pump is running.
Posted Fri Jul 15, 2005, 11:43pm Subject: Re: Please help me with my lever
i had another good look this morning and i found that when i leave it on the middle setting, quite a bit of water does trickle out so long as the lever is in the middle (no pump action though; just water oozing out). In fact, i can also hear it trickling out.... even when my PF is locked in the group head.
i can imagine the scenario: PF full of coffee being soaked by water just before the actual brewing takes place.
ps...come to think of it, the reason why i hear the preinfusion must be because i haven't flushed long enough....its the "crackling" or water dancing on the shower screen that i hear.
i have to do more comparisons tomorrow to see the taste difference when i manually preinfuse vs lever all the way up straight away. i might even purposely over- preinfuse for say, 10-15secs just to see if it will amplify any difference in taste.
Indeed, that's why "manual preinfusion" in this case is a bit of a misnomer. There's no pressure left in the HX after the cooling flush, and if you wait for it to build up, the temperature will be off. C'est la vie, mon ami.
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