The Silvia has a reputation for producing good coffee. And thats due to its thermostability.
Its when you start poking around with a thermocouple and digital multimeter you appreciate just how good it is for a very simple machine with no electronic control other than an on/off thermostat (which really could do with improving, Mr Rancilio).
I hava a permanently attached K-type thermocouple on the roof of the boiler.
Another is a roving one, and Ive tried different locations: in the basket, and on the exterior of the chunky group.
Room temperature 16C.
With the machine preheated for an hour, this is what happens when the boiler reads 108C, indicating conditions ideal for a pour.
Top of boiler: 108C
Basket fluctuated between 93C and 95C for the duration of a 25 second pour (without coffee). With coffee, this is most likely to fluctuate even less, to within 1C, as the grounds absorb and smooth out heat.
Temperature on the group stayed steady at 66C.
Group temperature is wonderfully static for a non-E61. It will go up as much as 2C through the entire heating 50-second cycle where boiler temperature can reach 120C, but by the time water comes back to a desirable 108, it will be 66C again and remain there.
Robusto
Its when you start poking around with a thermocouple and digital multimeter you appreciate just how good it is for a very simple machine with no electronic control other than an on/off thermostat (which really could do with improving, Mr Rancilio).
I hava a permanently attached K-type thermocouple on the roof of the boiler.
Another is a roving one, and Ive tried different locations: in the basket, and on the exterior of the chunky group.
Room temperature 16C.
With the machine preheated for an hour, this is what happens when the boiler reads 108C, indicating conditions ideal for a pour.
Top of boiler: 108C
Basket fluctuated between 93C and 95C for the duration of a 25 second pour (without coffee). With coffee, this is most likely to fluctuate even less, to within 1C, as the grounds absorb and smooth out heat.
Temperature on the group stayed steady at 66C.
Group temperature is wonderfully static for a non-E61. It will go up as much as 2C through the entire heating 50-second cycle where boiler temperature can reach 120C, but by the time water comes back to a desirable 108, it will be 66C again and remain there.
Robusto

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