Posted on 11 March 2011 by Nate
Once again, we’re continuing our perfect shot walk through tour and this time we’re going to take a look at how to maintain a proper boiler temperature with your Rancilio Silvia. The temperature within the boiler of your Rancilio Silvia is crucial in creating a perfect shot of espresso and there are a few methods for doing this which range from low-tech to super-geek, so let’s look at a couple of these and you can evaluate how you are going to approach achieving a consistent temperature with your Rancilio Silvia.
First, a look at why temperature is important…
Believe it or not, the temperature of the water which is used during the extraction of your espresso can have a tendency to accentuate and elicit certain strong flavors from the coffee. Generally speaking, a high water temperature tends to being out bitter flavors while a low temperature accentuates the more acidic range of the coffee’s flavor profile. Thus, to produced a balanced flavor from your origin or blend of choice, maintaining a suitable and stable temperature is critical. Generally, the widely accepted starting point for proper espresso extraction from most blends is 228°F, or 109°C.
How the Rancilio Silvia manages temperature…
Miss Silvia employs a single brass boiler which incorporates a simple thermostat. The heavy-duty brass boiler is capable of incredibly consistent heat management, however, the thermostat range varies by quite a few degrees. Essentially, once the machine is turned on, the heating element is activated and brings the boiler up to the top range of its temperature cycle. Once the boiler temperature reaches the lower end of the range, the thermostat kicks the heating element on and brings the temperature back up.
How you can manage temperature with the Rancilio Silvia…
Now, the temperature range from one machine to the next can vary somewhat, but straight out of the box, Miss Silvia tends to range from 210°F to 240°F (99°C to 116°C). This is a huge range of fluctuation. Since we want to brew at about 228°F (109°C), we need to find a way to manage the temperature of extraction. The simplest method of achieving the proper temperature is known as temperature surfing. In essence, we’re simply trying to start the brew cycle at the appropriately timed point in the boiler’s temperature cycle itself, or as close to 228°F (109°C) as we can get by guessing. Here are the steps involved:
*Let the machine warm up fully. This should take 20 to 30 minutes.
* Tamp your ground espresso into the portafilter and lock it into place in the group head.
*Place a small bowl or cup under the steam wand and open the valve completely. Flip the hot water switch on (not the brew switch). Once the orange light turns on indicating that the boiler is beginning to heat again, shut off the hot water switch and close the steam valve.
*As soon as the orange light comes on, activate a timer or stopwatch that indicates seconds. I use the stopwatch in the clock app on the iPhone for this.
*When the timer or stopwatch reaches 60 seconds after the heating element has turned on, it’s time to brew your shot. Follow the rest of the steps in the perfect shot walk through for proper extraction time. Generally, the orange light stays on for around 60 seconds, indicating that the light (and heating element) will shut off right at about 1 minute, however, I still like to time it as it can vary depending on how long the machine has been on.
Since the top end of the boiler cycle tends to hover around 240°F (116°C) and you’re going to lose about 20°F as the water moves through the machine and into the portafilter, this is going to put your temperature in the portafilter very close to 220°F (104°C).
If you’ve spent any amount of time reading about the Rancilio Silvia on the internet, you’re probably aware that there are electronic methods of stabilizing the temperature within the boiler to a range of less than +/-1F. Many vendors online offer what’s known as a PID kit for the machine (proportional, integral, and derivative controller). This unit essentially manages the intervals of the heating element’s on and off cycle to maintain and stabilize boiler temperature and allows it to stay on for several sections or even a fraction of a second depending on what is required to maintain the stable temperature. Temperature input is managed by an electronic unit mounted in the face of the machine and you can experiment with various temperatures for your origin or blend of choice. These units vary in price, but tend to go for around $300USD. They’re relatively easy to install and well worth the investment if you’re serious about proper home espresso extraction.
So there you have it. Proper temperature is critical to a great shot of espresso from the Rancilio Silvia, but with a little practice (or $300), you can mitigate this variable and produce excellent espresso every time.