"Turn on your machine and wait at least 15 -20 minutes so that it is thoroughly warmed up. Get a small styrofoam cup of the take-out variety and mark a line measuring the 2 ounce level, and another mark measuring the 3 ounce level. In metric terms that's roughly 60 ml and 90 ml respectively. Next, you will need to find a good quality dial type frothing thermometer and insert it horizontally through the cup. The point of the thermometer should not puncture the other side and the thermometer should be inserted low enough in the cup that the stem is covered by water. Place the cup along with the thermometer underneath your group and turn ON the brew switch and draw at least two ounces of water. Turn OFF the brew switch when you have enough water in the cup. Measure the maximum temperature achieved. Repeat this test several times in a row using the 2 ounce mark. Do the test again using the 3 ounce mark.
If you are not attaining at least 192F (89C) in all tests, then your thermostat is running too cool. I would be tempted to either return the machine or replace the thermostat."
I did this four times for 2 oz (60 ml) and four times for 3 oz (90 ml). I waited approximately 1-2 minutes between times, used half a plastic squeezy bottle for the water and a Thermapen to measure the temperature. http://thermapen.co.uk/ I had the portafilter in when I did the tests.
My measurements are as follow:
60 ml -
90 ml -
So my question is, should I care about not hitting the 89C/192F that the guide states is the target?
I think my espressos are a good temperature but this test got me wondering.
I agree with Nobby here, the cup/thermometer method is only a rough indicator at best. It will always be cooler than the true temp of the water, no thermometer is able to react fast enough to be more than a rough guess using this method.
You are in the ball park of what would be expected using this method, which has been around for a long time. It is not new and we have talked about it many, many times here.
If it was accurate enough to gauge the true temp of the machine, there would be no need for built in gauges on the machine it's self let alone digital readouts using very fast acting thermocouples. Yes I know the thermalpin is a thermocouple but it still has a lag, more than the thermocouples that are built into the machines or even after market PID units.
In real life, my name is Wayne P. Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!
Feed the newbs, starve the trolls and above all enjoy what you drink!
You say that you had the portafilter in place when you did these tests. Is this correct?
It should not be in place - you should be measuring the water temperature when it leaves the shower screen, before it would come into contact with the coffee if the portafilter was loaded and in place. The portafilter will be cooler than the water, even if thoroughly preheated, and so your readings will be lower than the true value.
Your values are fine. A few other variables that make the cup method of temperature difficult are height of the cup/how much air does the water free fall through, did you preheat the cup and thermometer with hot water until immediately before the test, does the cup have thermal mass or does it rapidly lose heat (Styrofoam was very good) and did you keep the PF on until immediately before you ran water into the cup. That can affect group temperature. Then watch the reading for a couple seconds and see how quickly the water temerature falls and realize that you are trying to get a very quick point in time temperature reading. What did you do to control where you started in the temperature cycle of the brewstat? The Gaggia boiler holds about 105 ml, so you are quickly exchanging the water, so the temperatures give an idea that the Gaggia boiler is almost a thermoblock.
Back to realize that "your values are fine," and you are contemplating a PID, so smile and be happy :)
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