I picked up an old La Marzocco Linea 3AV from John's Cafe in Palo Alto this past June. At first I didn't realize how old it was or how bad the condition it was in when I bought it. I got it because it was available and seemed like a reasonable restore. I learned practically everything about the the machines. La Marzocco machines are known for their temperature stability due to the two boiler system they came out with. These machines have a boiler specifically for steam and a separate or sometimes multiple brew boilers which are used exclusively for that purpose. The brew heads are headed with water from the brew boiler. These machines are solid and if properly maintained can last for years and years. Both boilers are stainless steal which adds to the value by providing anti-corrosive properties. The pump motor is external and a series of solenoid switches control the flow of water into and out of the boilers. On the AV models a little box called a flowmeter with a propeller inside is used to measure volume. the propeller is turned by water pressure provided by the pump. On the propeller are two tiny magnets which as they spin induce a current in a coil just above the propeller. The current is read by a control board and is used to time the opening and closing of the solenoid switch to provide to proper volume for the espresso shot. The solenoids also contain coils of wire which current is flows through them created a magnetic field which opens and closes the inlet for water to flow out the brew head.
The Linea I bought was filthy inside and out as you can see from the photos. I have my work cut out for me. The process of discovery took time too. The older models used a bolt and nut system to attach the brew heads which created lots of problems with leaks and scaling inside the brew boiler. Finding parts and going through years of grim took more than a month.
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