Brew temperature not hot enough or is thermometer wrong? - Page 2

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cannonfodder
Team HB
Posts: 10497
Joined: 19 years ago

#11: Post by cannonfodder »

Try a different coffee.
Dave Stephens

dman777 (original poster)
Posts: 57
Joined: 12 years ago

#12: Post by dman777 (original poster) »

When I pull a shot I wait for the boiler light to go off, and I pull the shot right afterwards. I am pulling a double shot at 16 grams. I notice towards the end of my 27 second shot the boiler light comes back on. Shouldn't the boiler be large enough to hold heated water for a 16 gram double shot? Also, does this mean that cooler water is hitting my shot near the end messing up the quality of the shot?

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entropyembrace
Posts: 330
Joined: 13 years ago

#13: Post by entropyembrace »

The problem is that you're pouring the water from the device that's heating the water, your silvia or a pot on the stove. Actually with your stovetop experiment I'm surprised that you only lost 12°F. When I'm brewing tea I know that if I pour hot water from the kettle in most teapots I will lose about 20°F if the teapot isn't pre-heated.

Use the method that's in the video Jonny posted (put the thermometer directly into the pot of boiling water) and you should get a reading of 212°F or very close.

But you're not going to get a good idea of what your brew temperature is by putting a cup under the shower screen and trying to measure the temperature of the water that collects in it...the water cools as it falls through the air and then cools even more when it hits the cup. I use a strip thermometer directly on the brew head of my La Pavoni to get a better idea...though that only tells me what the brew temp is when I'm actually brewing. Unfortunately, I'm not sure if that would work or not with the design of the Silvia case...does anyone know?

Billc
Posts: 304
Joined: 15 years ago

#14: Post by Billc »

The accuracy and precision of the thermometer are only parts of the error you are experiencing. One of the most problematic issues with this type of measurement instrument is the response time. If you are measuring meat in the oven, it is great because you stick it in and wait to see what the temperature is. In the case of measuring water coming out of the espresso machine the response time becomes critical. If you let the water run into the cup you are losing quite a bit of heat. You also lose even more while it is sitting in the cup waiting for a measurement. I have seen up to 30 degrees difference. There is an easy way to check for this. Place your thermometer into boiling water, after 60 seconds recorded the measured temperature. Then let the thermometer cool to room temperature. Now get a timer ready and record the time it takes to get from room temperature to the temperature recorded earlier. If this time exceeds 10 seconds you will have a very hard time making any accurate measurements. The Scace device takes about 1 second. A bead probe with a fluke multimeter is close to 1 second. The best way to use the "meat' type thermometers is to measure the water exiting the group head by removing the shower screen and measure the stream of exiting water right at the group. This minimizes the heat loss of sitting in a cup and also traveling through the air.


BillC

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