I have a new Silvia. I am trying to get an idea of the temps, but they seem alot cooler than they should be. I used a 5 inch Rattleware Frothing thermometer.

Machine has been on for about 45 minutes.

The PF is off and the self made cup is flush with the group head.

The results are pretty consistent. I've taken them about 7 times.

After the boiler light goes out, I can reach 198 F max with the water running at 20 seconds. If I wait 1:15 seconds after the boiler light goes out, the temp is still 198F. What kind of temp surfing is that?

I poured boiling water from the stove into that cup contraption I made and the most I got was 200 F. However, when the thermometer is out in the air left unused it shows the exact same temp. as my apartment AC/heater thermostat. So in one way it looks calibrated, in another way it looks not.

Is there something wrong with my machine? Or is it the thermometer?




Double shot pulls:

You should boil water on your stove and measure its temperature. It should be 212 unless you live much above sea level. That would be a better reference than room temperature.

dman777 wrote:...they seem a lot cooler than they should be.

Based on the temperature measured (which appears reasonable for the location) or on the results in the cup (which you didn't mention)? Your shots look fine. How do they taste?

+1 for thermometer calibration in the intended working range - like speedometers, accuracy varies across the scale. For the latter, accuracy at "0" is all but useless, while accuracy at highway speed is everything. As well, a mechanical thermometer, such as the one in your photo, probably responds too slowly for measuring changing brew water temps. You might have a better chance with a low-mass fast-read digital model.

The shots taste rather to high...almost sour and bitter. So, that is why I decided to look at the temp. I'm using Red Bird Espresso roasted on Jan 7.

I have no experience with Red Bird, but it seems to have a reputation on HB for tolerating a fair range of temperatures.

"Sour" and "bitter" are usually dominant at opposite ends of a range, respectively low and high. If you have trouble separating them, you might try exaggerating the low and high temps, by a longer surf in the first case, or by using the steam switch to keep the boiler light on for a few more seconds in the second case.

Here's a rough but easy gauge to try first: with a full boiler, fully warmed machine and no PF in place, wait for the high point of the temp cycle (boiler light goes out) and turn on the brew switch. You should have superheated water coming out, as evidenced by sound (hissing and sputtering) and sight (more steam and splashing than at normal brew temp). If not, your brew stat is defective - opening at too low a temp. I base this on my experience since 2003 with the original stat and one replacement. Not to rule out the possibility that Rancilio may have changed them since, but not as far as I've heard; more recent Silvia buyers may know more.

With a clearer mind, after hours of practicing on my espresso machine, I boiled water again on the stove. I placed the boiled water in a cup with the Rattleware thermometer. The highest the thermometer would get is 200 degrees F, when it should of been 212. Since, it's 12 degrees off...I just add it to the 198 I get from the Silvia after the boiler light goes off....which places it at 198+12=210 degrees. I test this specific scenerio about 5 times and each time was consistent at 198+12=210 degrees...exactly to the degree each time. It even stayed at that degree when I tested it 60 seconds after the light went out. Only when I tested it 2:30 minutes after the boiler light went out did I see a temp drop by 7 degrees.

Again, it's weird how this thermometer can accurately record the air temp in my apartment(using my ac/heater wall thermometer)...but for liquids in which it was made for(froth thermometer) it is 12 degrees off consistently.

So, could it be that if I pull at shot at 212 degrees that it would create that strong high taste(to me similar to sour)? I went to the coffee shop and their shot had the same high taste...but not as strong.

not sure what you mean by high taste but if you brew at that temp it will taste bitter/burnt, not how a coffee shop should taste. Too low and it will taste sour like a lemon. Here is how to calibrate your thermometer:


These thermometers aren't as good at measuring air temps so that may explain the contradiction.

dman777 wrote:...but for liquids in which it was made for(froth thermometer) it is 12 degrees off consistently.

Keeping in mind that frothing maxes around 135-140F, it no doubt is much closer to being right when frothing as opposed to boiling. I have had several higher range thermometers designed for frying and grilling, because I use them in my roaster and my grill, and probably half of them have been off by >=10 degrees F. And once you drop one, all bets are off. My favorite was a Taylor that is now discontinued (which I of course dropped), but my one sample of a Weber 9815 is pretty accurate, though its response is a little sluggish compared to the Taylor, which I still use, though now (after the drop) I have to add 15 degrees to the reading.

dman777 wrote:The shots taste rather to high...almost sour and bitter. So, that is why I decided to look at the temp. I'm using Red Bird Espresso roasted on Jan 7.

I know my temperature. Although simpler apparatus, La Pavoni -- after I pour boiling water from the microwave to replenish the boiler's last-usage depletion, which is enough to be already on and heating. A token from the microwave goes into the drinking glass first (aka - a-la' a Pavoni cup heaterupper). The boiler is then filled more than full, reason because all that's going out, at first pressure, through the PF to warm it for half- to sight-level at full remaining. Now, it's business time, shoot the shot, ground into the basket and set aside while the water was coming to boil in the microwave. With cold milk, there's a negligible effect on the glass holding the water. Emptied and immediately refilled for steamed milk, the glass remains hot. Forgoing artistic expression, the espresso shot pulled over, is then coming from a temperature regulated boiler, through a massive copper bottom, but preheated PF.

Apart from all happening fast, just not too fast, there's little else to go wrong after removing temperature for correct operating parameters with a clean machine. Apart from tasting imperfect, then the grinder's off.

Switched to a single-dose basket tonight, grinder near its fineness limit, tamped hard and difficult to pull, but the result was great. Probably play with that, tuning the tamp and grinder for the single basket.

you cant pour the boiling water in your cup contraption. You need to put the thermometer directly in boiling water. You're losing a ton of heat when you pour, and also waiting for your thermometer to read. Place the bottom part of your thermometer in a pot of boiling water and then wait and see what the reading is. It might still be off, but closer than 200 for sure.