At some point in the recent year or so, I think my Duetto 2 starting showing fairly significant brew boiler temperature swings. It's most obvious after pulling a shot, which makes sense, but the swings are up to 7 deg F or so. Idling swings can be 2-3 deg F. These are all after the machine has been on for a while to heat up sufficiently (1+ hours). Our water is quite soft, but it seems it could be a crusting of mineral deposits on the temperature probe after 6 years of use. Before removing the probe for inspection (always a risk of messing up something), it seemed worthwhile to consult the crowd...

Since I seem to have lost track of its initial out of the box performance, my question is to other Duetto or E61 DB owners: what is expected for brew boiler temperature stability? I would suspect that I have a mineral deposit or other probe problem. I would expect that idling temperature shouldn't fluctuate more than +-1 deg F, and that temperature after pulling a shot shouldn't fluctuate as much as I'm seeing (not sure exactly what's "normal").

I've played with the PID settings multiple times and think it helped a little.

I think that it's likely that the swings have been increasing gradually over time. There was a fairly long period when I didn't have much time for hobbies and it may have been then that things got less precise.

Have you tried the settings suggested on the Coffeetime wiki?

http://coffeetimex.wikidot.com/izzo-ale ... d-settings

wingnutsglory wrote:I would expect that idling temperature shouldn't fluctuate more than +-1 deg F, and that temperature after pulling a shot shouldn't fluctuate as much as I'm seeing (not sure exactly what's "normal").

If you mean the display temperature from the brew boiler probe, be aware that some manufacturers intentionally put it close to the water inlet to react more quickly. But generally speaking, the idle temperature on the double boiler E61s I've used will swing 1°F or maybe 2°F when idle. I don't pay much attention to the reading immediately after a shot; it should settle down within 90 seconds to the idle behavior.

Bob_McBob wrote:Have you tried the settings suggested on the Coffeetime wiki?

http://coffeetimex.wikidot.com/izzo-ale ... d-settings

Thanks for posting that. Yes, I have. Those helped a little but post-tuning variance is still pretty high.

I would start at the probe(s) like you mentioned.
Just go slow and you'll be fine. Have your chosen cleaning solution ready so you can clean and reinstall.
Also, perhaps a reset of the PID to factory defaults just in case...