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Pre-Infusion for the Rancilio Silvia Espresso Machine.
If you have any intention of using any kind of pre-infusion, you should fully understand this diagram below.
Understand why never flip the brew switch "on" before the pump is running and never leave the brew switch "on" when not in brew cycle.
of this specific boiler design we could have some amount of air trapped at
the top of the boiler. This air is acting as a dampener or cushion for the
force coming from the pump. In certain condition this event can be very
because of this specific boiler design we could have variation in the
amount of air in the boiler every time we brew. Therefore, if you attempt
to pre-Infuse when the boiler is not properly full, you will have great
negative effect on the extraction.
particular when trying any Pre-infusion (with time pause), It can dampen
water output. Therefore we can have great inconsistency in extractions
(volume and temperature).
There are a few ways of
adapting Silvia for pre-infusion. One is with a pre Infusion chamber/s, but this
option has some negatives such as difficult installation, always having zero
water pressure at start of pre-infusion and back flow of water after the pull. A
second option is a built in pre-infusion timer in the PID unit or on an external
timer, like a countdown switch. I find this option also has some negatives, such
as the lack of flexibility to pull a longer shot or to cut off short as needed
during the pull. Sometimes you may need 18 second and sometimes as much as 30 or
40 seconds. The third option is a combination of electrical switching, with the
user manually activating the pump as needed, together with monitoring the
extraction and the pressure at the gauge. I think the third option is the best
compromise because you can run the pressure at any range from zero to maximum,
sequence the pump and the water to the puck and pull the shot for any length of
Some other benefits of the electrical switching
option with an added low voltage switch:
The principal negatives:
See picture below with a side switch.
Preinfusion with an additional mini switch low voltage switch
Preinfusion, Rancilio Silvia, Bottomless, nice clip.
One other more practical option is, using Silvia’s own switches as you can see in the video below. This will require an additional electrical wiring modification. Do Not try this without the electrical wiring modification (it will not work).
Simple manual switching
Converting the existing switches to manual switching
Instruction kit sold by request at $15
Simple manual switching
Bear in mind that the ability to predict
timing is no guarantee of a good shot.
What is critical is knowing when to stop the pull for the particular coffee blend, grind and volume
and water temperature.
Always remember that bitter, harsh, astringent taste is the result of over extraction. Over extraction may be caused by (a) too long of an extraction (too much water by volume passing through the puck or even through a single spot or area of the puck), (b) uneven water distribution in the puck due to cracks, and/or (c) uneven grind distribution or density.
The Instituto Nationale Espresso Italiano (PDF)