Lelit Bianca brew temperature far too hot

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by catmug »

Hey all - have a Lelit Bianca that is less than a month old. Seeing some very odd behavior with the brew-boiler temperature that started to show around week 2. Intermittently, the brew water will be far too hot when exiting the grouphead, violently flashing to steam immediately after the pump is engaged, when the PID (and actual boiler-temp) are far below local boiling point. A few notes:
  • I have tried with the PID set as low as 192f to 198f, in case the PID offset is a few degrees out of the spec (10c off). This hasn't resolved the issue.
  • I live at 5280ft, where boiling should be roughly ~202.5
  • When issue occurs, the "true" boiler temp as read on the LCC appears normal, and equal to the PID set temp.
  • Once the machine is warm (30+ minutes), as soon as the issue occurs, no amount of flushing can bring the temperature in-line. Even at 70+ seconds of flushing, it's still sputtering/steaming. This tells me the boiler is probably quite far above the boiling point, even if it's not reading as such.
  • Via trial and error, I have been successful with one "strategy" (if you can call it that): immediately when the machine is turned on, I run the pump for 3-4 seconds. For some reason, this 'priming' seems to keep the brew boiler from getting too hot, at least for a while (1hr-ish). Eventually though, after an hour or two, it typically gets too hot.
  • I am reservoir operated at the moment, with softener filter.
  • Pump is set via bottom screw to 11bar.
I am in touch with the company I purchased it through and awaiting next steps, but also wanted to get opinions here and see if anyone has run into this issue. I certainly haven't seen it (on this machine, or any) after lots of searching/googling.

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#2: Post by slipchuck »

Is there a delay when the water comes out when you engage the lever?

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catmug (original poster)

#3: Post by catmug (original poster) »

@Randy - Yes, when the machine is cold I would say it's about a 3-4 second delay before I see water exiting the group. When it's warm, it's instant.

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#4: Post by slipchuck » replying to catmug »

That is very unusual for a new machine. Is your water really hard?

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#5: Post by catmug (original poster) »

slipchuck wrote:That is very unusual for a new machine. Is your water really hard?
I've measured it with test strips, per the recs from the retailer (Clive). Out of the tap it was moderately hard (~80-100). I'm running it through a Brita filter first which has brough the hardness down to measure about ~30-50ppm, and then I have the stock Lelit resin filter in the tank, which should bring it lower than that...

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#6: Post by another_jim »

The likeliest reason for what you are seeing is that Lelit overheats the boiler on a cold start to get the machine ready in 20 minutes but does not do this on a start from standby. The standby start leaves the machine cooler than the cold start when it first shows that its ready. Chances are you may need to recalibrate the offset and settle on a consistent warm up routine.

The bench review post about programming the offset gives the details.
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#7: Post by catmug (original poster) » replying to another_jim »

First, thanks for the info - read many of your posts before I bought it!

I did consider re-configuring the offset, but it seemed so far off to me (to the point where I didn't think it was worth messing with it) since I couldn't fathom that the offset would deviate by +10f. But, I'll give it a try using your 'flash boil' method as I don't have a scace.

Do you have any suggestions on a consistent warmup routine? Is there anything I should be doing?

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#8: Post by another_jim »

Don't use the standby; just shut it down and restart. Wait about 25 minutes to half an hour. That will get you consistent performance.

My guess is that you will then see flash boiling all the time, because your offset is too high. Given your altitude, you don't have a lot of margin for error. The machines tend to be +/-5F on the offset. At sea level that doesn't show up as flash boiling; at your altitude it will.
Jim Schulman

catmug (original poster)

#9: Post by catmug (original poster) » replying to another_jim »

Thanks Jim. I did some calibration this afternoon...or, I attempted to. To make things simple, I set the offset (Ec) to "0" - so, whatever temp the screen reads...is the temp in the boiler. Keep in mind that my local boiling point is 95c.

I waited 30m between adjustments, and took videos at 100c, 105c, and 110c. Those results all measured up:
  • 100c: No boiling, just water
  • 105c: Boiling, pretty vigorous
  • 110c: Boiling, very vigorous
Makes sense, right? Then I bumped the PID to "101c", waited 30m for stabilization, and tried the test again. And my results were...completely bonkers. Here's the video:
I will note that I also set the screen to show "true temp". While the boiler was idling, I saw the temperatures fluctuate from 89c to 112c, which makes no sense. At times, it was ping-ponging back and forth between temps as quickly as the screen could refresh.

Clive has suggested that I should to snug up the internal "expansion valve" in case the boiler is improperly venting. Their other thought is that it could be a bad thermoprobe. Any thoughts?


#10: Post by Bluenoser »

If it shows your temperature fluctuating, perhaps your temperature sensor is bad.. somehow it is likely not giving you the correct reading? One main point of failures in anything electronically controlled is the sensing.

Certainly if the sensor is somehow either bad, or something is interfering with it reading the correct temperature, then the PID will not be able to keep your water a consistent and/or proper temperature. I used to play with temperature sensors in the past.. and I don't know what type are used in espresso machines.. but if water somehow gets into them.. they become erratic..