La Marzocco Linea Brew Boiler Control

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pas
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#1: Post by pas »

Hi,
Does anyone know how the pressure/temperature is regulated on a La Marzocco Linea's brew boiler? I know that there is a pstat on the steam boiler but I cannot see how the brew boiler is controlled.

Thanks!

RockyIII
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#2: Post by RockyIII »

For the brew boiler, the Linea Mini uses a PID controller with an analog adjusting wheel on the left side of the machine, but there is no readout.

Rocky

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TomC
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#3: Post by TomC »

OP doesn't mention a Linea Mini. But on the original Linea, from 2011 and newer, the brew boiler is PID controlled. Prior to this it was via a pressure stat. The pressure, of course, is provided by the outboard rotary pump.
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RockyIII
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#4: Post by RockyIII replying to TomC »

Tom,

I misread. Thanks for the correction.

Rocky

pas (original poster)
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#5: Post by pas (original poster) »

Mine is a 2006ish 3 group Linea. So it must be controlled by a pstat.

Thanks for your responses!

boost
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#6: Post by boost »

To be precise it's actually controlled by thermostat and the adjustment is via screw so a bit similar to pstat.


pas (original poster)
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#7: Post by pas (original poster) »

Ah, that makes sense! I didn't think I saw another pressure stat, which was why I was wondering.

One additional question about how dual boiler machines provide pressure to the group, if you guys don't mind. I am used to a hx machine, so I have no problem understanding how the pump delivers the pressure to the group with technology like that. On dual boiler machines, like this Linea, I have more difficulty. Does the pump pump new water into the brew group while the user is extracting a shot and so it becomes a fully pressurized system? I seems a bit weird like that because you would be bringing cold water into your hot tank and your stability would be gone. Or does it work more like lever machines without a pump that build enough pressure just based on the temperature of the boiler?

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erics
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#8: Post by erics »

. . . if you guys don't mind.
And you have been to the manufacturer's website? http://www.lamarzoccousa.com/

And you have been to the downloads section of this website? /downloads/

But, to answer your question, the pump sends water to, and thus pressurizes the brew boiler which sends water to the appropriate group because the particular brew solenoid valve for that group opens simultaneously with the running of the pump.
Skål,

Eric S.
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E-mail: erics at rcn dot com

pas (original poster)
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#9: Post by pas (original poster) »

Oh I got it. Thanks.
I have been to the La Marzocco website, they don't explain the theory behind their machines, just schematics etc.
I did not know about the downloads section here!

Thanks for all your help!

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stuartmac
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#10: Post by stuartmac »

They make a very nice kit to replace that mechanical brew boiler stat with a pid.

I'm looking at doing the upgrade myself.

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