Getting accurate shot temperature displays on PIDed double boilers without a thermometer - Page 5

[another_jim (original poster)]

A Bianca user did this twice, once with and once without the steam boiler on. He discovered a difference of 2C in the offsets. There is no piping or electrical interaction between the two boilers in the Bianca; so the effect is purely a result of having the hot boiler in the vicinity adding extra heat to the group and thermosyphon loop.

Have others noticed this on DBs with switchable steam boilers? Is my lack of experience with these beasties showing?

[pizzaman383]

I noticed that having the steam boiler of my VBM DD on vs off made my shot temperature 1-2 degrees different with the same boiler setting.

[Graham J]

A Bianca user did this twice, once with and once without the steam boiler on. He discovered a difference of 2C in the offsets. There is no piping or electrical interaction between the two boilers in the Bianca; so the effect is purely a result of having the hot boiler in the vicinity adding extra heat to the group and thermosyphon loop.

Have others noticed this on DBs with switchable steam boilers? Is my lack of experience with these beasties showing?

As I previously used this technique to set up my Bianca, with the steam boiler on, I went back to test the difference with it turned off.
I started by checking the "steam & bubble" with the steam boiler on and the display set at 100C. This just to remind me what the sound and appearance looked like. I waited 1.5 hours with the steam boiler off then reran the test. There was slightly less noise but "steam & bubble" were very similar. Bottomless portafilter left in during the idle stage but removed for the flow tests.
So I wouldn't want to argue with anyone who says they measure a 1C difference, with and without steam boiler on. On my machine the difference is not as much as 2C subjectively, because I've been able to detect the difference between 98C and 100C on the display quite readily when using this setup technique.
This is still a valid way to get in the sweet spot for temperature setup. 1-2C differences may matter to some; if so they should probably acquire some additional grouphead measurement technology.
I'd say that this set up technique works well for fine-tuning your PID controlled E61. With the twin twin boiler design, just use the setup (steam boiler on/off) that is normal practice for your coffee making.
My Bianca only needed a 2C adjustment from the manufacturers set point and I like to live in 16C room temperature house during the 6-8 months of autumn winter. That may be somewhat colder than the norm and also affects fine-tuning the setup.

[another_jim (original poster)]

I don't think it's a big deal; but it is something users should be aware of.

[SeaRizz]

I began attempts to tune my Bianca's PID by setting the brew boiler to 210f first and allowing the Bianca to stabilize for an hour. When I began flow, I noticed the lever was rather stiff, which gave me pause. I expect from metal expansion at higher temps? I experienced no flash boiling at the group so adjusted PID to 211f, allowed the group to stabilize for 30 minutes, and then again to 212f at which point engaging the lever did not activate the pump. I released the lever and tried again and the pump engaged as expected. I was a little freaked out by this, and the fact that at temperatures approaching boiling, the lever was becoming uncomfortably stiff, I abandoned the test. Is this behavior to be expected? Bianca's, not mine that is!

Upon returning to 205f and below as a brew temp on the PID, the lever has since been freely moving and feels quite normal and I have yet to experience a lack of pump engagement upon lever movement. I have not had call to go beyond 205f since. Is there any chance of damaging the circuitry, pump or other internals to Bianca if I complete testing?

[another_jim (original poster)]

No, this is completely off. You are describing three separate problems. 1) the pump is engaged by a button activated by the levetta's visible cam, either you are not bringing the levetta all the way up, or the button needs repair. 2) Stiffness in the levetta is created when the coffee oils on the internal cam driving the valves are stripped by chemical backflushing. Make a few shots and it will go away. 3) The brew boiler and group temperatures have nothing to with either problem. If you see immediate flash boiling at 212, you are in calibration. If you saw no boiling, even after a few seconds, at 211, you are too cool. When you restart the test, you may as well start at 213 or 214.

Finally, this post is kind of off topic. Any kind of calibration work on a machine presupposes you are comfortable using it, and it is in good working order. If these problems don't resolve, please post in the Binaca User experience thread for further suggestions.