Reservoir here too.

Reservoir here too.

Hi Larry, any chance that you can post the linea mini flow schematics?

Thank you

Yeah, I need to do that!

It is a most interesting set of plumbing!!!

Hi. I also would appreciate flow and/or electric circuitry diagrams of the Linea Mini (in order to add a very simple line-pressure pre-infusion).

Best,

M.

Hi again. In the absence of any electrical circuitry diagrams, would anybody know how the one-second pre-infusion is realized in the Mini? Obviously, the one or other solenoid opens directly when the switch is engaged, but the pump kicks in only a second later. So the questions would be: Which valve is opened immediately for preinfusion and where does the pre-infusion water stem from (this is not line pressure, since pre-infusion works with the tank-only machine in the absence of pump action)? How is the one-second delay controlled (that is: how is the signal processed in the brainbox? Are all funtions for the delay hard-wired into the brainbox?)?

M.

PS: Very specific questions for a forum newbie, maybe. But I'm tinkering with espresso machines for a loing time. Some of the older folks may know my nick from alt.coffee...

Someone will give a better answer than this one... but in another thread it was described that the preinfusion is a function of the pressure in the brew flow path. After you flush the group, the pressure is ~12 bars (depending on machine settings), when you engage the paddle, the pressure drops to zero and then immediately increases as the pump starts. From my understanding, the water that is in the flow path causing that 12 bar pressure is the preinfusion water. Again, I probably don't have the details 100%, but this is my understanding of it.

Hi Jacob, this is also my understanding. This would imply that when engaging the switch, the valve close to the brewhead would open first. A second later, the second valve (more towards the pump) would open, along with engagement of the pump. It is unclear to me where exactly the 12bars of pressure come from when idle. In addition to water, there must be an amount of compressed air that aids in expelling the pre-infusion water.

A hydraulics diagram would indeed come in handy...

M.

Hi all. Another try to get my hands on an LMLM hydraulic diagram. This is why:

I tried today to exchange the 0.8mm gicleur for the 0.6mm variant. I failed since I could not get a good grip on the stock gicleur to unscrew it. However, since I was lazy and did not turn off line pressure before opening the boiler, I realized that water was slowly flowing into the boiler through an orifice to the lower right side. Took about 2min. for the (200ml) boiler to fill up again. Untill I finally closed the line pressure valve.

Now, this behaviour was never mentioned in any instructions here or in the German kaffeenetz forum. I wonder whether it was normal, or whether there is a damaged valve in the machine. Since I have no good idea of the water circuitry in the machine, I also do not know what the orifice in the boiler is good for. Any ideas, anyone?

FWIW, the coffee from the machine is excellent.

M

I don't have any software for drawing hydraulic circuits, so I sketched on paper and took a picture of it. I've never seen anything else quite like the water circuit in the LMLM. It is quite complicated, has 4 check valves, a pre-heated water path and a blending point for cold and pre-heated water, an orifice which controls water exit rate to the brew solenoid valve, which feeds back into the brew group and a convoluted water path and finally onto the shower screen.

Description:
1. Water from the reservoir or plumb-in line enters the rotary pump.
2. Check-valve 1 is on the outlet of the rotary pump, connected to a loop of hose.
3. Water enters from the hose to T-fitting #1 which feeds T-fitting #2 and water through check-valve #2 for the heat exchanger loop inside the steam boiler.
4. T-fitting #2 splits water between the steam boiler solenoid fill valve and check valve #3, and through check valve #4 through an orifice to supply cold bypass water to the 4-way cross.
5. The 4-way cross blends cold water and pre-heated water, provides the tap point for the brew pressure gauge, and feeds water to the integrated brew block water chamber.
6. Water is heated inside the integrated brew block water chamber. An adjustable relief valve regulates the chamber pressure to 12 bars and exhausts into the drip tray.
7. An orifice (0.8mm standard) leads to the water chamber exit into the brew solenoid valve.
8. The brew solenoid valve opens and loops water back into the integrated brew block lower chamber into the convoluted water path.
9. The convoluted water path consists of a machined passage in the brew block and a coarse threaded, "screw" which greatly lengthens the water path. A temperature sensor is inserted inside the water screw and is used to regulate the boiler temperature.
10. After exiting the convoluted water path, the water continues through a passage to the shower screen distribution screw, shower screen and brew basket.