Gaggiunio Classic Pro - How it works - DIY - part 3

This is part 3 of my build notes for the Gaggiunio coffee machine.

Parts 1 & 2 are here:

   Part 1 Gaggiuino Build Log with Workflow intro

   Part 2 Gaggiuino V3 - Build Log Notes - switches, PCB

The build might change as I work through various issues... which will obviously happen.

I'll update as I go along.

Some links:

Gaggiuino Project Page

https://gaggiuino.github.io/

Discord;

https://gaggiuino.github.io/#/community/community-media

facebook:

https://www.facebook.com/groups/5362374853865845/

Every build is different.

There are so many versions of the Gaggia classic.

Thanks to Zer0-bit and the coffee community for making this possible

The inside of a Gaggia Classic.

Before I start pulling the Gaggia apart, I thought it would be a good idea to see how it works, and hopefully understand some of the main components.

When you first turn the machine on, the heaters start to work.

This is the first job of the machine .... to heat water.

Depending on the mode selected (brewing or steaming) the steam & boiler thermostats will switch on and of. When the boiler gets to brewing temp it switches off, ... as its cools down, it will switch back on.

If steam mode is selected, the higher steam thermostat will be turned on., etc.

 

The Gaggia Classic Pro has a vibration pump that pulls water from the reservoir and pushes it into the boiler via the OPV (over pressure valve) or pump safety valve.

The pressure of this valve is limited at 9 - 15 bar (depending on the machine).

This valve has 1 input & 2 outputs.

Water flows in and pushes on a spring-loaded seal. 

If the pressure is below the pressure limit, the seal will stay closed & direct water through the first output, which is used to brew coffee. 

When the pressure of the water is too high, the spring will be compressed & the seal will open, directing water through the 2nd (overflow) output. This leads back to the pressure outlet tube & drip tray.

This water is heated by the walls of the boiler, in which two heating elements are mounted.

This heated water also streams to the 3 way solenoid valve (left pic) which directs that water back into the group head (but also blocks any output to the drip tray). 

Here the water can flow through the dispersion plate/shower screen, which are both mounted to the bottom of the group head.

When the solenoid is off, water can flow from the group to the drip tray.

The water will only flow through the group head when you flick the brew button on.

Turning on the brew switch activates the pump.

Deactivating the brew switch stops the pump & simultaneously switches the 3-way solenoid valve  to allow hot water from the group head to flow to the drip tray via the pressure outlet tube.

Thus, pressure is now removed from the group head & portafilter.

This is the original boiler water thermostat (no 32).

The pic above isn't clear. Its at the base of the boiler.

It will be replaced in the Gaggiuino with a thermocouple

so I will probably need to remove the boiler to get to it.

This replaces the boiler water thermostat .

Just screw it in with lots of thermal paste.

The steam thermostat is at the top of the machine... in the centre of the pic .... much easier to access.

+ Gaggia Classic Evo Pro - Modding with arduino - Gaggiuino

   Part 1 Gaggiuino Build Log with Workflow intro

   Part 2 Gaggiuino V3 - Build Log Notes - switches, PCB

   Part 3 Gaggiunio mod - The original Classic Pro - How it works

   Part 4 Gaggiuino - boot first time 

   Part 5 Gaggiuino - wiring

   Part 6 Gaggiuino boiler & pump removal