Silvia has one little problem with its steam process. The steam valve will leak steam and water as it cools.
To prevent the steam valve from dripping water after you've steamed milk for your latte or cappucino (or your wife's hot chocolate!), you can run boiler water through the wand to cool the steam valve.
When you steam milk, you turn on the steam button, which bypasses the "brew thermostat" and switches you to the "steam thermostat." Instead of the brew thermostat's nominal 110°C (or the later ones at 100°C), the steam thermostat trips much higher (mine trips at 305°F). I usually start steaming my milk when it gets to 290°F.
My point is that the steam valve gets hot when you're running steam though it. When I finish steaming milk, the steam wand and steam valve are both hot.
Let's remember that metal expands when it gets hot. Therefore, when you turn off the steam switch and close the steam/water valve after steaming, the valve is nice and water-tight — while it's still that hot.
But, when the temperature cools down to the normal temperatures controlled by the brew thermostat, the valve will cool off and the metal will shrink enough to allow water to drip occasionally from the steam wand.
Some people miss the problem. They turn Silvia on to preheat, make their espresso, switch to steam mode, steam their milk, and then turn Silvia off. They won't have any issue as long as refill her boiler now (by turning on the water switch or brew switch) or remember to add some more water to the boiler when they turn Silvia on again).
But, if you leave Silvia running all the time, like I normally do, so I can get an espresso or Americano, or just to have a source of hot water for tea or for cooking, you'll get water all over the counter if you forget to cool the steam valve.
After I steam milk, I turn Silvia's water switch on and then open the steam valve. I let the boiler refill and then discharge water through the steam wand into a small pitcher until the boiler temp reads 190°F (on the display on my PID). If I didn't have a PID, I'd just let it run until there wasn't any steam coming off the water that discharged.
Then, having cooled the steam valve, I can close the valve and it doesn't leak. Just in case, I keep that small pitcher under the steam wand all the time.
Copyright © 2002-2007 Terry A. Stockdale