AJuar DavecUK I have made the two tests, and in both cases the machine tends to fail in a potential failure condition (not always). Also, in one case out of 20 approximately, with the boiler priority, the machine has showed very different pressure behaviour even with the steam boiler off, from cold. I have the video of this but I’m not going to upload because I know that you trust me. This should be an evidence of a capricious mechanical little valve stuck? I don’t know.
You have ruled out software as the issue then because if it was a software bug it would fail every time.
I cannot understand how a valve or plumbing would have this effect. You tried with HX off and on which includes or eliminates the 2 halves of the brew circuit, and noticed the same behaviour. This means those sections of the brew circuit cannot be at fault?
Logically this leads to the fault being outside the sealed brew circuit (or at either end of it)…but it doesn’t make sense on how this could have the effects you are observing?
- If it’s the pump end, there is always "push from the pump and I can’t see how an intermittently leaky 1 way valve would have this effect
- A leaky autofill valve would drop the pressure but you would see the service boiler overfilling over time (you should check this). Even so, I don’t see how a leak could cause a pressure peak, unless it’s chattering (leaking on/off/on/off), possibly that might affect the PIDs ability to control the pump. Even so if it was leaking why only when the steam boiler is on…perhaps it’s warming up and then the defect is showing? It might be the reason why the fault doesn’t present itself until the service boiler has been on a while?
So check whether the boiler is overfilling and if it is it might be the autofill valve…?
My confusion about the autofill valve is 4 machines, all done it from new, all with faulty autofill valves that cause PID issues in a particular way when the service boiler is on…..doesn’t sound very probable does it. Especially as I am only guessing on something having this effect.
If I’m honest I don’t know, it doesn’t make sense and I couldn’t reproduce it, which means I couldn’t find the cause?
