Our method of addressing Temperature fluctuation (or “temperature surfing”.)
If you’ve done any research about the Rancilio Silvia on online discussion forums, chances are you’ve come across talk of something called “temperature surfing.” Temperature surfing refers to a very involved method of regulating the temperature of the brew water. It requires determining the precise water temperature relative to the machine’s position in the boiler heating cycle and timing the preparation of your shots accordingly. Some people recommend timing the shot while the boiler is heating (how many seconds since the boiler power indicator light switches on.) Other methods recommend timing the shot as the boiler is cooling (how many seconds after the light switches off.) There are a number of different methods described on various websites; some are quite simple while others require specialized measurement devices and repeated scientific experimentation. How deeply involved you care to get is entirely up to you.
However, for most people this process will be too tedious for their daily routine, and might even dissuade them from getting into espresso at all, or to choose more automated espresso machines over the Rancilio Silvia. Over the years we’ve tested many of different ways to regulate temperature on the Silvia, and we believe there’s a simpler way. It may not be as precise as some of the 19 step processes you’ll find discussed online, but for most people it will suffice to pull a sweet, rich shot that is neither under- nor over-extracted.
In short, we recommend that you steam the milk first, then bleed off the excess pressure and steam out of the grouphead. If you leave the brew switch on for about 15-25 seconds, or until the steam dissipates and only water is coming out of the grouphead, there should be enough of a temperature drop in the boiler that the thermostat will force the boiler to start heating up again. Once the boiler has turned off, if you wait about 30 seconds, you’ll be pretty close to 200 degrees Fahrenheit and ready to pull a good shot. This process should take 2-3 minutes, which is just about the time you’ll need to grind and tamp in preparation for pulling a shot. Be sure to swirl and gently knock your pitcher of steamed milk to maintain consistent texture and “keep it alive.”