La Marzocco Linea Mini brew pressure questions - Page 3

#21: Post by **nuketopia** » August 14th, 2017, 9:44 pm

LMAO, no freaking possible way that being in the vicinity of an air conditioner will appreciably cool the brew boiler. It just can't happen. If it is dropping pressure rapidly, it's leaking, period.

I said it works best when the brew pressure idles right near the 12 bar mark. That's my experience in over a year of ownership. The manual clearly says it shouldn't be allowed to go higher, but that's where you set it.

The LMLM brew hydraulic circuit is not at all connected to the steam boiler. It does have a heat exchanger passage through it (partial pre-heating of the water input to the brew boiler), but there's virtually no interaction between the two.

#22: Post by **RockyIII** » August 14th, 2017, 9:58 pm

nuketopia wrote:The LMLM brew hydraulic circuit is not at all connected to the steam boiler. It does have a heat exchanger passage through it (partial pre-heating of the water input to the brew boiler), but there's virtually no interaction between the two.

If that is the case, then the cycling I see that appears to be in unison must be coincidental.

Rocky

#23: Post by **wpK** » August 15th, 2017, 10:57 am

I adjusted my machine to go to 12 bars after switching off the paddle but within a minute or so it goes down to 11 bars.

Just to be clear is supposed to go to 12 bars and the stay right under 12 bars? Because when I adjust the valve to idle at 12 bars it will spike to 13 right after switching off the paddle and then fall back down to 12.

August 15th, 2017, 12:34 pm

Adjust it so the spike doesn't go over 12. It sounds like the pressure relief valve is a little slow to react. If it holds 11, it should be fine.

#25: Post by **nuketopia** » August 15th, 2017, 12:37 pm

RockyIII wrote:If that is the case, then the cycling I see that appears to be in unison must be coincidental.

Rocky

Part of the high pressure brew water path goes through a heat exchanger tube that passes through the steam boiler. There will be some slight interaction with the steam boiler by virtue of this and perhaps any slight leakage through a check valve.

#26: Post by **LaMini** » August 16th, 2017, 11:39 am

nuketopia wrote:The brew pressure gauge however, will not indicate at all what the brewing pressure at the puck is. To measure the actual brewing pressure, you'll need a tool, like a SCACE-II device. The brewing pressure is adjusted on the pump body with a nut and bolt.

I did change the 0.8mm orifice (aka jet or gicleur) to a 0.6mm which is available from LM parts. There was a big thread on that subject some months ago. It does change the rate at which water flows out of the brew boiler, and has some side effects like slowing the rate at which pressure rises in the brew head. It has a side effect of altering the final pressure - which means you just have to re-calibrate with the SCACE to really know the brew pressure. Honestly, I don't think it made a lot of difference.

Hello, great post! You have wrote before that you're not sure if the .6mm is better and also said that maybe the problem was the Grinder. Did you install back the .8mm?

I also did the .6mm swap and adjust the pressure to 6 BAR, since you used the Scace, how 6 BAR at the gauge translate to the puck? Now that I have a Monolith Conical, I'm thinking of going back to at least 9 BAR at the gauge and see if that works. Thanks

August 17th, 2017, 8:48 pm

nuketopia wrote: When the machine is idle, the brew pressure gauge should indicate 12-bar.

I adjusted my pressure today so that it is at 12 bar when idle. I am now able to notice a short 1-second pre-infusion time when flipping the paddle on with no portafilter installed, which wasn't the case before -- it was just full on instantly -- So this tip helped. Thanks!

I also pulled the best shot I've pulled on the machine so far after the adjustment. Not sure if it's coincidental or not, but I am much happier today than I was a week ago with my results on this machine.

#28: Post by **nuketopia** » August 17th, 2017, 9:23 pm

alpine0000 wrote:I adjusted my pressure today so that it is at 12 bar when idle. I am now able to notice a short 1-second pre-infusion time when flipping the paddle on with no portafilter installed, which wasn't the case before -- it was just full on instantly -- So this tip helped. Thanks!

I also pulled the best shot I've pulled on the machine so far after the adjustment. Not sure if it's coincidental or not, but I am much happier today than I was a week ago with my results on this machine.

Yes, it seems to be the idle pressure and what little pre-infusion the LMLM does are related. My experience matches yours.

#29: Post by **baristabazza** » August 18th, 2017, 5:54 am

Do any of you have your LMLM plumbed in? My changes in pressure settings has had the same results as you and I am running off the internal reservoir. I wonder if mains pressure onto the brew circuit would affect the quantity/quality of preinfusion compared to tank supply? Cheers

August 18th, 2017, 9:41 am

I'm using the reservoir.

Rocky