OFFSET numbers

bill castellano

Hi
I have a new LR (a month old) and If m getting some medium roast (Chromatic Gamut)beans dialed in and wanted to adjust the pre-infusion pressure upwards a notch (now that the other variables have settled), to get more taste in the shot. I opened up the machine and noticed the OFFSET was set to -1.4. I did notice in other threads that you do recommend -1.0 so I adjusted that and left the others as they were. In the settings menu, The “Bar” said 6.5 and the “Set “was 3.0.

I waited a half hour and pulled my shot (19.5g in, 38g out) and noticed the difference right away, definitely a richer flavor.

Question is: did that change in OFFSET bump up my preinfusion pressure a little? I would guess so, but I am not sure. Figured I’d ask before making other changes, exactly what the OFFSET does.

I must say The LR is a delight and has changed my home espresso game immensely.

Thanks!

Bill

Reiss Gunson

hi bill

the offset compensates for the drop in pressure from the point at which the pressure transducer is located to the puck

this drop i have measured to be 1.0 bar, which needs to be entered as an offset value of -1.0 (causing the value displayed on the console to drop by 1.0 bar)

for whatever reason our electronics supplier set the default offset to -1.4 bar

it needs to be -1.0 bar

hope this helps

kind regards

reiss.

bill castellano

I suppose my real question is: by changing the offset from -1.4 to -1.0, am I effectively increasing my pre-infusion pressure, leaving all other things the same?

Reiss Gunson

no, you are reducing it (the greater a negative offset value is the higher the pressure the pump needs to deliver to reach the same target pressure)

for example:

assume the offset value was zero and the pressure at the transducer was 4 bar

if you then changed the offset value to -1 the displayed pressure at the transducer would change to 3 (assuming it was still measuring 4)

kind regards

reiss.