Is a drop in brew temperature normal with PID controllers? - Page 2
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another_jim
- Team HB
- Posts: 13947
- Joined: 19 years ago
It's what I would use. Bear in mind: there is an offset between the temperature it's reading and the one the puck is experiencing. use your own taste to "calibrate" the readings. Sour and weak is too low; bitter and aggressive is too hot.SiliconLunch wrote: To Jim: thanks for clarifying the error in my measurements. I can see now how a free-flow rate is quite a bit different to the espresso flow rate. Before I go for my Scace device (), how trustworthy would you think the PID LED temperature display would be, when the filter basket is full and we're extracting at the espresso rate?
You will always get a temperature drop during shots; you should learn to associate what range is associated with a good balanced flavor. You have not got a La Marzocco; this means you will have restrictions on the kind of shots you can make. Once you find a warmup procedure and shot time that works, stick to it. Make sure that whatever dose & grind setting variations you use allow you to maintain these temperature parameters.
The machine has a decent sized boiler, but not one large enough to stop the temperature from dropping. You should grind fine enough and dose high enough to slow your shot down so you read around 95C at the start and 90C at the end. With a PID on this style machine, you can experiment putting the switch to steam as soon as the shot starts, this will force the heat on immediately, and may stabilize the temperature a little bit more that you are seeing now.
Jim Schulman
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Billc
- Posts: 304
- Joined: 15 years ago
Nico,
I will add that it is somewhat important to know where the temp probe is located when analyzing the boiler temp. Of course the Scace Device is the way to go and what is most important is what's coming out of the group head.
As cold water enters the boiler the probe may see this early enough to correct the temp. Most machines are designed such that the cold water will be directed to the bottom of the boiler and the hot water exits through the top. So, just because the temperature display reads low it does not necessarily mean that the water exiting the group head is that low.
The display temp is really only accurate in a steady state condition. Once water is added to the boiler it does not necessarily correspond to the water exiting the group head.
The thermapen you are using is pretty fast so you should get some good measurements but you will have to hold the tip as close to the exit of the water as possible. Without the portafilter in place the water can loose temp very quickly upon exit.
BillC
I will add that it is somewhat important to know where the temp probe is located when analyzing the boiler temp. Of course the Scace Device is the way to go and what is most important is what's coming out of the group head.
As cold water enters the boiler the probe may see this early enough to correct the temp. Most machines are designed such that the cold water will be directed to the bottom of the boiler and the hot water exits through the top. So, just because the temperature display reads low it does not necessarily mean that the water exiting the group head is that low.
The display temp is really only accurate in a steady state condition. Once water is added to the boiler it does not necessarily correspond to the water exiting the group head.
The thermapen you are using is pretty fast so you should get some good measurements but you will have to hold the tip as close to the exit of the water as possible. Without the portafilter in place the water can loose temp very quickly upon exit.
BillC
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erics
- Supporter ★
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- Joined: 19 years ago
See below pic. Part number MC741 is a NTC (negative temperature coefficient) thermistor held against the top surface of the boiler.I guess another relevant question would be, where exactly is the Lelit TC located?
Also, I do not believe the thermofilter would fit your machine as your grouphead is 57 mm.
