As one of 1st-line's customer's, I truly appreciate Jim's feedback on this forum. As a reseller, they are in a unique position to see the same issues crop up time and again across multiple machines and customers (most of whom I'm sure don't post here). With this data, they may be able to draw inferences about root cause that might not be obvious just by reading posts on this forum. This is not just valuable information for us, but also the manufacturer who can correct defects like this, and I believe there is a defect here.
What is missing from this conversation is a real root cause analysis. I am encouraged to hear that Lelit has hired a water expert, and hope they are engaging other experts to find out what is behind these overpressure events as well as an appropriate corrective action. The message I've heard so far is that many (most?) of the customers encountering this issue have been using certain water formulas, and most of the time (but not all?) it can be corrected by cleaning the temperature probe and changing water. This is a strong clue at the root cause, but this cannot be the end of the story and there is still a lot of work to do here.
I can't help but relate this to my own line of work - I have spent the last few decades as an engineer in the aerospace industry - and our own industry's methods for getting at root cause through the Failure Review Board, or FRB. There are many examples familiar to the public - a failed shuttle launch due to a brittle O-ring launched on a cold Florida day, a space telescope with an optical aberration due to an incorrectly manufactured calibration tool, a Mars orbiter crashing into the red planet due to a mix-up in English vs metric units in the ground navigation software. (Aside... one of my favorite examples from TV comes from the recent miniseries Chernobyl, which unfolds like a mystery where the root cause is finally revealed as... ok I won't spoil it but do yourself a favor and watch this show.) All of these high-profile catastrophic failures were investigated with an FRB, but most FRBs are encountered during ground test, designed to find root cause and correct more innocuous-seeming issues (e.g., an electronics board which occasionally fails to reply to a command) before they turn into a billion-dollar problem. In these reviews, hypothetical root causes are laid out, often in a "fishbone" chart, and systematically ruled out until what remains, like a Sherlock Holmes case, turns out to be the true cause. The corrective action is just as important, mitigating the risk of similar problems in the future.
I'm sure Lelit does not have the resources to conduct a full aerospace-style FRB, but it sure seems in their best interest to do what they can. The repercussions of not fixing issues like this include expensive warranty headaches, lost customers, dealers deciding to drop products, damaged reputation, etc. I would propose the following questions to investigate:
- What are the observables? Clutch stated that his steam boiler temperature probe measurement was jumping erratically, perhaps between a false (low) reading and the true temperature. Are other owners seeing the same behavior, or are some different, such as a reading which is consistently low?
- What hardware do all of these cases have common? Is it the same temperature probe? Same sensor technology (e.g., same NTC thermistor and/or digital converter IC)? Same Gicar controller? How about the boiler? Same stainless-steel alloy?
- Are there any manufacturers or machines using the same parts identified above that do not suffer from this issue? If so, what is different about these machines?
- Water is a prime suspect here, but I haven't seen anything in these 9 pages of posts to draw a conclusion. Are there any ingredients in common to most of these failures (e.g., I've heard Epsom salt recipes mentioned)? If so, I also wonder if Lelit is able to reproduce the issue with the same ingredient(s) and then resolve it by removing the "film" from the probe. I also can't ignore Clutch's experience with his brand new machine and Brita filtered tap water, which does not fit the model here. It could be that his case is unique, and he has a loose electrical connection with his temperature probe.
All of this should ultimately result in a corrective action. If it is as simple as avoiding water formulas with a certain list of ingredients, that would be easy (and should get stamped as a warning on every user manual going forward). If it is traced to a style of temperature probe, then Lelit (and other manufacturers using this probe) should at least conduct a recall or extend warranty coverage to replace this specific probe when it goes bad.
I'm ending my long post here. I am quite interested to see how this resolves, as I plan on owning and enjoying my Bianca for many years.