BES900 and pre infusion ?

System

SS and I am sure this will raise more questions than answer.

1: Breville manual.

Low Pressure Pre-Infusion:

Gradually increases water pressure to gently expand grinds for an even extraction.

Preinfusion time:

We recommend a range of between 5-15secs as being optimum.

Preinfusion power:

We recommend a range of between 50-65 as being optimum.


Questions.

So for those that like numbers; If the BES900 is expected to perform like any number of commercial and prosumer machines as in controlled Temp and an OPV set correctly...

A:  When to start counting re shot time ?

B:  50 - 60 power = what 
(% of pump capacity, if so then some where between 4.5bar and 7bar as the OPV is out of the equation ?)

C:  Why would you be looking at 5- 15sec for low pressure pre infusion ?

shape_shifter

What is it and why do we need it? Is it a taste thing as to where you put it, at present I have it at the default of 7/8 and am about to put it down to 3.

soloespresso

on 1320314799:

See post above for WHY... Sorry (late edit) If your overdosing and compacting you puck; then it does not really work, as 2 or 3 bar can only wet the surface by direct contact and the grinds can not take the moisture up...

Slightly OT, but is updosing the em6910 + preinfusion on the em6910 contradictory concepts then.

Brett H

Hi Soloesoresso, i was under the impression that updosing on the 6910 is a no no due to the potential collar damage.  Also, the style of pre infusion of the 6910 with it's pulsing of the pump would exacerbate an up dosed puck in regards to  channels surely.  It's an interesting question and I'm thinking AM or another guru will confirm of otherwise shotly. :D